Absorb gitlab_git @ 6b077df2b68158cf8e069e3ffd6359aff038a438absorb-gitlab-git

48 files changed, 6793 insertions, 11 deletions

diff --git a/Gemfile b/Gemfile
index f2291568d25..f2412db7498 100644
--- a/Gemfile
+++ b/Gemfile
@@ -49,9 +49,7 @@ gem 'u2f', '~> 0.2.1'
 # Browser detection
 gem 'browser', '~> 2.2'
 
-# Extracting information from a git repository
-# Provide access to Gitlab::Git library
-gem 'gitlab_git', '~> 10.7.0'
+gem 'rugged', '~> 0.24.0'
 
 # LDAP Auth
 # GitLab fork with several improvements to original library. For full list of changes
@@ -279,6 +277,10 @@ group :development, :test do
   gem 'spinach-rails',      '~> 0.2.1'
   gem 'spinach-rerun-reporter', '~> 0.0.2'
 
+  # gitlab_git
+  gem 'rspec-mocks'
+  gem 'rspec-its'
+
   # Prevent occasions where minitest is not bundled in packaged versions of ruby (see #3826)
   gem 'minitest', '~> 5.7.0'
 
diff --git a/Gemfile.lock b/Gemfile.lock
index 81b43f2238a..95856cdd389 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -283,11 +283,6 @@ GEM
       mime-types (>= 1.16, < 3)
       posix-spawn (~> 0.3)
     gitlab-markup (1.5.0)
-    gitlab_git (10.7.0)
-      activesupport (~> 4.0)
-      charlock_holmes (~> 0.7.3)
-      github-linguist (~> 4.7.0)
-      rugged (~> 0.24.0)
     gitlab_omniauth-ldap (1.2.1)
       net-ldap (~> 0.9)
       omniauth (~> 1.0)
@@ -612,6 +607,9 @@ GEM
     rspec-expectations (3.5.0)
       diff-lcs (>= 1.2.0, < 2.0)
       rspec-support (~> 3.5.0)
+    rspec-its (1.2.0)
+      rspec-core (>= 3.0.0)
+      rspec-expectations (>= 3.0.0)
     rspec-mocks (3.5.0)
       diff-lcs (>= 1.2.0, < 2.0)
       rspec-support (~> 3.5.0)
@@ -869,7 +867,6 @@ DEPENDENCIES
   github-linguist (~> 4.7.0)
   gitlab-flowdock-git-hook (~> 1.0.1)
   gitlab-markup (~> 1.5.0)
-  gitlab_git (~> 10.7.0)
   gitlab_omniauth-ldap (~> 1.2.1)
   gollum-lib (~> 4.2)
   gollum-rugged_adapter (~> 0.4.2)
@@ -946,12 +943,15 @@ DEPENDENCIES
   responders (~> 2.0)
   rouge (~> 2.0)
   rqrcode-rails3 (~> 0.1.7)
+  rspec-its
+  rspec-mocks
   rspec-rails (~> 3.5.0)
   rspec-retry (~> 0.4.5)
   rubocop (~> 0.43.0)
   rubocop-rspec (~> 1.5.0)
   ruby-fogbugz (~> 0.2.1)
   ruby-prof (~> 0.16.2)
+  rugged (~> 0.24.0)
   sanitize (~> 2.0)
   sass-rails (~> 5.0.6)
   scss_lint (~> 0.47.0)
diff --git a/app/models/merge_request_diff.rb b/app/models/merge_request_diff.rb
index dd65a9a8b86..3e1bec1c521 100644
--- a/app/models/merge_request_diff.rb
+++ b/app/models/merge_request_diff.rb
@@ -1,7 +1,7 @@
 class MergeRequestDiff < ActiveRecord::Base
   include Sortable
   include Importable
-  include EncodingHelper
+  include Gitlab::Git::EncodingHelper
 
   # Prevent store of diff if commits amount more then 500
   COMMITS_SAFE_SIZE = 100
diff --git a/changelogs/unreleased/absorb-gitlab-git.yml b/changelogs/unreleased/absorb-gitlab-git.yml
new file mode 100644
index 00000000000..0279d8a0fba
--- /dev/null
+++ b/changelogs/unreleased/absorb-gitlab-git.yml
@@ -0,0 +1,4 @@
+---
+title: Absorb gitlab_git
+merge_request: 
+author: 
diff --git a/lib/gitlab/git/attributes.rb b/lib/gitlab/git/attributes.rb
new file mode 100644
index 00000000000..42140ecc993
--- /dev/null
+++ b/lib/gitlab/git/attributes.rb
@@ -0,0 +1,131 @@
+module Gitlab
+  module Git
+    # Class for parsing Git attribute files and extracting the attributes for
+    # file patterns.
+    #
+    # Unlike Rugged this parser only needs a single IO call (a call to `open`),
+    # vastly reducing the time spent in extracting attributes.
+    #
+    # This class _only_ supports parsing the attributes file located at
+    # `$GIT_DIR/info/attributes` as GitLab doesn't use any other files
+    # (`.gitattributes` is copied to this particular path).
+    #
+    # Basic usage:
+    #
+    #     attributes = Gitlab::Git::Attributes.new(some_repo.path)
+    #
+    #     attributes.attributes('README.md') # => { "eol" => "lf }
+    class Attributes
+      # path - The path to the Git repository.
+      def initialize(path)
+        @path = File.expand_path(path)
+        @patterns = nil
+      end
+
+      # Returns all the Git attributes for the given path.
+      #
+      # path - A path to a file for which to get the attributes.
+      #
+      # Returns a Hash.
+      def attributes(path)
+        full_path = File.join(@path, path)
+
+        patterns.each do |pattern, attrs|
+          return attrs if File.fnmatch?(pattern, full_path)
+        end
+
+        {}
+      end
+
+      # Returns a Hash containing the file patterns and their attributes.
+      def patterns
+        @patterns ||= parse_file
+      end
+
+      # Parses an attribute string.
+      #
+      # These strings can be in the following formats:
+      #
+      #     text      # => { "text" => true }
+      #     -text     # => { "text" => false }
+      #     key=value # => { "key" => "value" }
+      #
+      # string - The string to parse.
+      #
+      # Returns a Hash containing the attributes and their values.
+      def parse_attributes(string)
+        values = {}
+        dash = '-'
+        equal = '='
+        binary = 'binary'
+
+        string.split(/\s+/).each do |chunk|
+          # Data such as "foo = bar" should be treated as "foo" and "bar" being
+          # separate boolean attributes.
+          next if chunk == equal
+
+          key = chunk
+
+          # Input: "-foo"
+          if chunk.start_with?(dash)
+            key = chunk.byteslice(1, chunk.length - 1)
+            value = false
+
+          # Input: "foo=bar"
+          elsif chunk.include?(equal)
+            key, value = chunk.split(equal, 2)
+
+          # Input: "foo"
+          else
+            value = true
+          end
+
+          values[key] = value
+
+          # When the "binary" option is set the "diff" option should be set to
+          # the inverse. If "diff" is later set it should overwrite the
+          # automatically set value.
+          values['diff'] = false if key == binary && value
+        end
+
+        values
+      end
+
+      # Iterates over every line in the attributes file.
+      def each_line
+        full_path = File.join(@path, 'info/attributes')
+
+        return unless File.exist?(full_path)
+
+        File.open(full_path, 'r') do |handle|
+          handle.each_line do |line|
+            break unless line.valid_encoding?
+
+            yield line.strip
+          end
+        end
+      end
+
+      private
+
+      # Parses the Git attributes file.
+      def parse_file
+        pairs = []
+        comment = '#'
+
+        each_line do |line|
+          next if line.start_with?(comment) || line.empty?
+
+          pattern, attrs = line.split(/\s+/, 2)
+
+          parsed = attrs ? parse_attributes(attrs) : {}
+
+          pairs << [File.join(@path, pattern), parsed]
+        end
+
+        # Newer entries take precedence over older entries.
+        pairs.reverse.to_h
+      end
+    end
+  end
+end
diff --git a/lib/gitlab/git/blame.rb b/lib/gitlab/git/blame.rb
new file mode 100644
index 00000000000..e84585f1879
--- /dev/null
+++ b/lib/gitlab/git/blame.rb
@@ -0,0 +1,75 @@
+module Gitlab
+  module Git
+    class Blame
+      include Gitlab::Git::EncodingHelper
+
+      attr_reader :lines, :blames
+
+      def initialize(repository, sha, path)
+        @repo = repository
+        @sha = sha
+        @path = path
+        @lines = []
+        @blames = load_blame
+      end
+
+      def each
+        @blames.each do |blame|
+          yield(
+            Gitlab::Git::Commit.new(blame.commit),
+            blame.line
+          )
+        end
+      end
+
+      private
+
+      def load_blame
+        cmd = %W(git --git-dir=#{@repo.path} blame -p #{@sha} -- #{@path})
+        # Read in binary mode to ensure ASCII-8BIT
+        raw_output = IO.popen(cmd, 'rb') {|io| io.read }
+        output = encode_utf8(raw_output)
+        process_raw_blame output
+      end
+
+      def process_raw_blame(output)
+        lines, final = [], []
+        info, commits = {}, {}
+
+        # process the output
+        output.split("\n").each do |line|
+          if line[0, 1] == "\t"
+            lines << line[1, line.size]
+          elsif m = /^(\w{40}) (\d+) (\d+)/.match(line)
+            commit_id, old_lineno, lineno = m[1], m[2].to_i, m[3].to_i
+            commits[commit_id] = nil unless commits.key?(commit_id)
+            info[lineno] = [commit_id, old_lineno]
+          end
+        end
+
+        # load all commits in single call
+        commits.keys.each do |key|
+          commits[key] = @repo.lookup(key)
+        end
+
+        # get it together
+        info.sort.each do |lineno, (commit_id, old_lineno)|
+          commit = commits[commit_id]
+          final << BlameLine.new(lineno, old_lineno, commit, lines[lineno - 1])
+        end
+
+        @lines = final
+      end
+    end
+
+    class BlameLine
+      attr_accessor :lineno, :oldlineno, :commit, :line
+      def initialize(lineno, oldlineno, commit, line)
+        @lineno = lineno
+        @oldlineno = oldlineno
+        @commit = commit
+        @line = line
+      end
+    end
+  end
+end
diff --git a/lib/gitlab/git/blob.rb b/lib/gitlab/git/blob.rb
new file mode 100644
index 00000000000..663617602b4
--- /dev/null
+++ b/lib/gitlab/git/blob.rb
@@ -0,0 +1,327 @@
+module Gitlab
+  module Git
+    class Blob
+      include Linguist::BlobHelper
+      include Gitlab::Git::EncodingHelper
+
+      # This number is the maximum amount of data that we want to display to
+      # the user. We load as much as we can for encoding detection
+      # (Linguist) and LFS pointer parsing. All other cases where we need full
+      # blob data should use load_all_data!.
+      MAX_DATA_DISPLAY_SIZE = 10485760
+
+      attr_accessor :name, :path, :size, :data, :mode, :id, :commit_id, :loaded_size, :binary
+
+      class << self
+        def find(repository, sha, path)
+          commit = repository.lookup(sha)
+          root_tree = commit.tree
+
+          blob_entry = find_entry_by_path(repository, root_tree.oid, path)
+
+          return nil unless blob_entry
+
+          if blob_entry[:type] == :commit
+            submodule_blob(blob_entry, path, sha)
+          else
+            blob = repository.lookup(blob_entry[:oid])
+
+            if blob
+              Gitlab::Git::Blob.new(
+                id: blob.oid,
+                name: blob_entry[:name],
+                size: blob.size,
+                data: blob.content(MAX_DATA_DISPLAY_SIZE),
+                mode: blob_entry[:filemode].to_s(8),
+                path: path,
+                commit_id: sha,
+                binary: blob.binary?
+              )
+            end
+          end
+        end
+
+        def raw(repository, sha)
+          blob = repository.lookup(sha)
+
+          Gitlab::Git::Blob.new(
+            id: blob.oid,
+            size: blob.size,
+            data: blob.content(MAX_DATA_DISPLAY_SIZE),
+            binary: blob.binary?
+          )
+        end
+
+        # Recursive search of blob id by path
+        #
+        # Ex.
+        #   blog/            # oid: 1a
+        #     app/           # oid: 2a
+        #       models/      # oid: 3a
+        #       file.rb      # oid: 4a
+        #
+        #
+        # Blob.find_entry_by_path(repo, '1a', 'app/file.rb') # => '4a'
+        #
+        def find_entry_by_path(repository, root_id, path)
+          root_tree = repository.lookup(root_id)
+          # Strip leading slashes
+          path[/^\/*/] = ''
+          path_arr = path.split('/')
+
+          entry = root_tree.find do |entry|
+            entry[:name] == path_arr[0]
+          end
+
+          return nil unless entry
+
+          if path_arr.size > 1
+            return nil unless entry[:type] == :tree
+            path_arr.shift
+            find_entry_by_path(repository, entry[:oid], path_arr.join('/'))
+          else
+            [:blob, :commit].include?(entry[:type]) ? entry : nil
+          end
+        end
+
+        def submodule_blob(blob_entry, path, sha)
+          Gitlab::Git::Blob.new(
+            id: blob_entry[:oid],
+            name: blob_entry[:name],
+            data: '',
+            path: path,
+            commit_id: sha,
+          )
+        end
+
+        # Commit file in repository and return commit sha
+        #
+        # options should contain next structure:
+        #   file: {
+        #     content: 'Lorem ipsum...',
+        #     path: 'documents/story.txt',
+        #     update: true
+        #   },
+        #   author: {
+        #     email: 'user@example.com',
+        #     name: 'Test User',
+        #     time: Time.now
+        #   },
+        #   committer: {
+        #     email: 'user@example.com',
+        #     name: 'Test User',
+        #     time: Time.now
+        #   },
+        #   commit: {
+        #     message: 'Wow such commit',
+        #     branch: 'master',
+        #     update_ref: false
+        #   }
+        #
+        # rubocop: disable Metrics/AbcSize
+        # rubocop: disable Metrics/CyclomaticComplexity
+        # rubocop: disable Metrics/PerceivedComplexity
+        def commit(repository, options, action = :add)
+          file = options[:file]
+          update = file[:update].nil? ? true : file[:update]
+          author = options[:author]
+          committer = options[:committer]
+          commit = options[:commit]
+          repo = repository.rugged
+          ref = commit[:branch]
+          update_ref = commit[:update_ref].nil? ? true : commit[:update_ref]
+          parents = []
+          mode = 0o100644
+
+          unless ref.start_with?('refs/')
+            ref = 'refs/heads/' + ref
+          end
+
+          path_name = Gitlab::Git::PathHelper.normalize_path(file[:path])
+          # Abort if any invalid characters remain (e.g. ../foo)
+          raise Gitlab::Git::Repository::InvalidBlobName.new("Invalid path") if path_name.each_filename.to_a.include?('..')
+
+          filename = path_name.to_s
+          index = repo.index
+
+          unless repo.empty?
+            rugged_ref = repo.references[ref]
+            raise Gitlab::Git::Repository::InvalidRef.new("Invalid branch name") unless rugged_ref
+            last_commit = rugged_ref.target
+            index.read_tree(last_commit.tree)
+            parents = [last_commit]
+          end
+
+          if action == :remove
+            index.remove(filename)
+          else
+            file_entry = index.get(filename)
+
+            if action == :rename
+              old_path_name = Gitlab::Git::PathHelper.normalize_path(file[:previous_path])
+              old_filename = old_path_name.to_s
+              file_entry = index.get(old_filename)
+              index.remove(old_filename) unless file_entry.blank?
+            end
+
+            if file_entry
+              raise Gitlab::Git::Repository::InvalidBlobName.new("Filename already exists; update not allowed") unless update
+
+              # Preserve the current file mode if one is available
+              mode = file_entry[:mode] if file_entry[:mode]
+            end
+
+            content = file[:content]
+            detect = CharlockHolmes::EncodingDetector.new.detect(content) if content
+
+            unless detect && detect[:type] == :binary
+              # When writing to the repo directly as we are doing here,
+              # the `core.autocrlf` config isn't taken into account.
+              content.gsub!("\r\n", "\n") if repository.autocrlf
+            end
+
+            oid = repo.write(content, :blob)
+            index.add(path: filename, oid: oid, mode: mode)
+          end
+
+          opts = {}
+          opts[:tree] = index.write_tree(repo)
+          opts[:author] = author
+          opts[:committer] = committer
+          opts[:message] = commit[:message]
+          opts[:parents] = parents
+          opts[:update_ref] = ref if update_ref
+
+          Rugged::Commit.create(repo, opts)
+        end
+
+        # Remove file from repository and return commit sha
+        #
+        # options should contain next structure:
+        #   file: {
+        #     path: 'documents/story.txt'
+        #   },
+        #   author: {
+        #     email: 'user@example.com',
+        #     name: 'Test User',
+        #     time: Time.now
+        #   },
+        #   committer: {
+        #     email: 'user@example.com',
+        #     name: 'Test User',
+        #     time: Time.now
+        #   },
+        #   commit: {
+        #     message: 'Remove FILENAME',
+        #     branch: 'master'
+        #   }
+        #
+        def remove(repository, options)
+          commit(repository, options, :remove)
+        end
+
+        # Rename file from repository and return commit sha
+        #
+        # options should contain next structure:
+        #   file: {
+        #     previous_path: 'documents/old_story.txt'
+        #     path: 'documents/story.txt'
+        #     content: 'Lorem ipsum...',
+        #     update: true
+        #   },
+        #   author: {
+        #     email: 'user@example.com',
+        #     name: 'Test User',
+        #     time: Time.now
+        #   },
+        #   committer: {
+        #     email: 'user@example.com',
+        #     name: 'Test User',
+        #     time: Time.now
+        #   },
+        #   commit: {
+        #     message: 'Rename FILENAME',
+        #     branch: 'master'
+        #   }
+        #
+        def rename(repository, options)
+          commit(repository, options, :rename)
+        end
+      end
+
+      def initialize(options)
+        %w(id name path size data mode commit_id binary).each do |key|
+          self.send("#{key}=", options[key.to_sym])
+        end
+
+        @loaded_all_data = false
+        # Retain the actual size before it is encoded
+        @loaded_size = @data.bytesize if @data
+      end
+
+      def binary?
+        @binary.nil? ? super : @binary == true
+      end
+
+      def empty?
+        !data || data == ''
+      end
+
+      def data
+        encode! @data
+      end
+
+      # Load all blob data (not just the first MAX_DATA_DISPLAY_SIZE bytes) into
+      # memory as a Ruby string.
+      def load_all_data!(repository)
+        return if @data == '' # don't mess with submodule blobs
+        return @data if @loaded_all_data
+
+        @loaded_all_data = true
+        @data = repository.lookup(id).content
+        @loaded_size = @data.bytesize
+      end
+
+      def name
+        encode! @name
+      end
+
+      # Valid LFS object pointer is a text file consisting of
+      # version
+      # oid
+      # size
+      # see https://github.com/github/git-lfs/blob/v1.1.0/docs/spec.md#the-pointer
+      def lfs_pointer?
+        has_lfs_version_key? && lfs_oid.present? && lfs_size.present?
+      end
+
+      def lfs_oid
+        if has_lfs_version_key?
+          oid = data.match(/(?<=sha256:)([0-9a-f]{64})/)
+          return oid[1] if oid
+        end
+
+        nil
+      end
+
+      def lfs_size
+        if has_lfs_version_key?
+          size = data.match(/(?<=size )([0-9]+)/)
+          return size[1] if size
+        end
+
+        nil
+      end
+
+      def truncated?
+        size && (size > loaded_size)
+      end
+
+      private
+
+      def has_lfs_version_key?
+        !empty? && text? && data.start_with?("version https://git-lfs.github.com/spec")
+      end
+    end
+  end
+end
diff --git a/lib/gitlab/git/blob_snippet.rb b/lib/gitlab/git/blob_snippet.rb
new file mode 100644
index 00000000000..e98de57fc22
--- /dev/null
+++ b/lib/gitlab/git/blob_snippet.rb
@@ -0,0 +1,32 @@
+module Gitlab
+  module Git
+    class BlobSnippet
+      include Linguist::BlobHelper
+
+      attr_accessor :ref
+      attr_accessor :lines
+      attr_accessor :filename
+      attr_accessor :startline
+
+      def initialize(ref, lines, startline, filename)
+        @ref, @lines, @startline, @filename = ref, lines, startline, filename
+      end
+
+      def data
+        lines.join("\n") if lines
+      end
+
+      def name
+        filename
+      end
+
+      def size
+        data.length
+      end
+
+      def mode
+        nil
+      end
+    end
+  end
+end
diff --git a/lib/gitlab/git/branch.rb b/lib/gitlab/git/branch.rb
new file mode 100644
index 00000000000..544f76f11dc
--- /dev/null
+++ b/lib/gitlab/git/branch.rb
@@ -0,0 +1,6 @@
+module Gitlab
+  module Git
+    class Branch < Gitlab::Git::Ref
+    end
+  end
+end
diff --git a/lib/gitlab/git/commit.rb b/lib/gitlab/git/commit.rb
new file mode 100644
index 00000000000..fb34322e18f
--- /dev/null
+++ b/lib/gitlab/git/commit.rb
@@ -0,0 +1,310 @@
+# Gitlab::Git::Commit is a wrapper around native Rugged::Commit object
+module Gitlab
+  module Git
+    class Commit
+      include Gitlab::Git::EncodingHelper
+
+      attr_accessor :raw_commit, :head, :refs
+
+      SERIALIZE_KEYS = [
+        :id, :message, :parent_ids,
+        :authored_date, :author_name, :author_email,
+        :committed_date, :committer_name, :committer_email
+      ].freeze
+
+      attr_accessor(*SERIALIZE_KEYS)
+
+      def ==(other)
+        return false unless other.is_a?(Gitlab::Git::Commit)
+
+        methods = [:message, :parent_ids, :authored_date, :author_name,
+                   :author_email, :committed_date, :committer_name,
+                   :committer_email]
+
+        methods.all? do |method|
+          send(method) == other.send(method)
+        end
+      end
+
+      class << self
+        # Get commits collection
+        #
+        # Ex.
+        #   Commit.where(
+        #     repo: repo,
+        #     ref: 'master',
+        #     path: 'app/models',
+        #     limit: 10,
+        #     offset: 5,
+        #   )
+        #
+        def where(options)
+          repo = options.delete(:repo)
+          raise 'Gitlab::Git::Repository is required' unless repo.respond_to?(:log)
+
+          repo.log(options).map { |c| decorate(c) }
+        end
+
+        # Get single commit
+        #
+        # Ex.
+        #   Commit.find(repo, '29eda46b')
+        #
+        #   Commit.find(repo, 'master')
+        #
+        def find(repo, commit_id = "HEAD")
+          return decorate(commit_id) if commit_id.is_a?(Rugged::Commit)
+
+          obj = if commit_id.is_a?(String)
+                  repo.rev_parse_target(commit_id)
+                else
+                  Gitlab::Git::Ref.dereference_object(commit_id)
+                end
+
+          return nil unless obj.is_a?(Rugged::Commit)
+
+          decorate(obj)
+        rescue Rugged::ReferenceError, Rugged::InvalidError, Rugged::ObjectError, Gitlab::Git::Repository::NoRepository
+          nil
+        end
+
+        # Get last commit for HEAD
+        #
+        # Ex.
+        #   Commit.last(repo)
+        #
+        def last(repo)
+          find(repo)
+        end
+
+        # Get last commit for specified path and ref
+        #
+        # Ex.
+        #   Commit.last_for_path(repo, '29eda46b', 'app/models')
+        #
+        #   Commit.last_for_path(repo, 'master', 'Gemfile')
+        #
+        def last_for_path(repo, ref, path = nil)
+          where(
+            repo: repo,
+            ref: ref,
+            path: path,
+            limit: 1
+          ).first
+        end
+
+        # Get commits between two revspecs
+        # See also #repository.commits_between
+        #
+        # Ex.
+        #   Commit.between(repo, '29eda46b', 'master')
+        #
+        def between(repo, base, head)
+          repo.commits_between(base, head).map do |commit|
+            decorate(commit)
+          end
+        rescue Rugged::ReferenceError
+          []
+        end
+
+        # Delegate Repository#find_commits
+        def find_all(repo, options = {})
+          repo.find_commits(options)
+        end
+
+        def decorate(commit, ref = nil)
+          Gitlab::Git::Commit.new(commit, ref)
+        end
+
+        # Returns a diff object for the changes introduced by +rugged_commit+.
+        # If +rugged_commit+ doesn't have a parent, then the diff is between
+        # this commit and an empty repo.  See Repository#diff for the keys
+        # allowed in the +options+ hash.
+        def diff_from_parent(rugged_commit, options = {})
+          options ||= {}
+          break_rewrites = options[:break_rewrites]
+          actual_options = Gitlab::Git::Diff.filter_diff_options(options)
+
+          diff = if rugged_commit.parents.empty?
+                   rugged_commit.diff(actual_options.merge(reverse: true))
+                 else
+                   rugged_commit.parents[0].diff(rugged_commit, actual_options)
+                 end
+
+          diff.find_similar!(break_rewrites: break_rewrites)
+          diff
+        end
+      end
+
+      def initialize(raw_commit, head = nil)
+        raise "Nil as raw commit passed" unless raw_commit
+
+        if raw_commit.is_a?(Hash)
+          init_from_hash(raw_commit)
+        elsif raw_commit.is_a?(Rugged::Commit)
+          init_from_rugged(raw_commit)
+        else
+          raise "Invalid raw commit type: #{raw_commit.class}"
+        end
+
+        @head = head
+      end
+
+      def sha
+        id
+      end
+
+      def short_id(length = 10)
+        id.to_s[0..length]
+      end
+
+      def safe_message
+        @safe_message ||= message
+      end
+
+      def created_at
+        committed_date
+      end
+
+      # Was this commit committed by a different person than the original author?
+      def different_committer?
+        author_name != committer_name || author_email != committer_email
+      end
+
+      def parent_id
+        parent_ids.first
+      end
+
+      # Shows the diff between the commit's parent and the commit.
+      #
+      # Cuts out the header and stats from #to_patch and returns only the diff.
+      def to_diff(options = {})
+        diff_from_parent(options).patch
+      end
+
+      # Returns a diff object for the changes from this commit's first parent.
+      # If there is no parent, then the diff is between this commit and an
+      # empty repo.  See Repository#diff for keys allowed in the +options+
+      # hash.
+      def diff_from_parent(options = {})
+        Gitlab::Git::Commit.diff_from_parent(raw_commit, options)
+      end
+
+      def has_zero_stats?
+        stats.total.zero?
+      rescue
+        true
+      end
+
+      def no_commit_message
+        "--no commit message"
+      end
+
+      def to_hash
+        serialize_keys.map.with_object({}) do |key, hash|
+          hash[key] = send(key)
+        end
+      end
+
+      def date
+        committed_date
+      end
+
+      def diffs(options = {})
+        Gitlab::Git::DiffCollection.new(diff_from_parent(options), options)
+      end
+
+      def parents
+        raw_commit.parents.map { |c| Gitlab::Git::Commit.new(c) }
+      end
+
+      def tree
+        raw_commit.tree
+      end
+
+      def stats
+        Gitlab::Git::CommitStats.new(self)
+      end
+
+      def to_patch(options = {})
+        begin
+          raw_commit.to_mbox(options)
+        rescue Rugged::InvalidError => ex
+          if ex.message =~ /Commit \w+ is a merge commit/
+            'Patch format is not currently supported for merge commits.'
+          end
+        end
+      end
+
+      # Get a collection of Rugged::Reference objects for this commit.
+      #
+      # Ex.
+      #   commit.ref(repo)
+      #
+      def refs(repo)
+        repo.refs_hash[id]
+      end
+
+      # Get ref names collection
+      #
+      # Ex.
+      #   commit.ref_names(repo)
+      #
+      def ref_names(repo)
+        refs(repo).map do |ref|
+          ref.name.sub(%r{^refs/(heads|remotes|tags)/}, "")
+        end
+      end
+
+      def message
+        encode! @message
+      end
+
+      def author_name
+        encode! @author_name
+      end
+
+      def author_email
+        encode! @author_email
+      end
+
+      def committer_name
+        encode! @committer_name
+      end
+
+      def committer_email
+        encode! @committer_email
+      end
+
+      private
+
+      def init_from_hash(hash)
+        raw_commit = hash.symbolize_keys
+
+        serialize_keys.each do |key|
+          send("#{key}=", raw_commit[key])
+        end
+      end
+
+      def init_from_rugged(commit)
+        author = commit.author
+        committer = commit.committer
+
+        @raw_commit = commit
+        @id = commit.oid
+        @message = commit.message
+        @authored_date = author[:time]
+        @committed_date = committer[:time]
+        @author_name = author[:name]
+        @author_email = author[:email]
+        @committer_name = committer[:name]
+        @committer_email = committer[:email]
+        @parent_ids = commit.parents.map(&:oid)
+      end
+
+      def serialize_keys
+        SERIALIZE_KEYS
+      end
+    end
+  end
+end
diff --git a/lib/gitlab/git/commit_stats.rb b/lib/gitlab/git/commit_stats.rb
new file mode 100644
index 00000000000..e9118bbed0e
--- /dev/null
+++ b/lib/gitlab/git/commit_stats.rb
@@ -0,0 +1,26 @@
+# Gitlab::Git::CommitStats counts the additions, deletions, and total changes
+# in a commit.
+module Gitlab
+  module Git
+    class CommitStats
+      attr_reader :id, :additions, :deletions, :total
+
+      # Instantiate a CommitStats object
+      def initialize(commit)
+        @id = commit.id
+        @additions = 0
+        @deletions = 0
+        @total = 0
+
+        diff = commit.diff_from_parent
+
+        diff.each_patch do |p|
+          # TODO: Use the new Rugged convenience methods when they're released
+          @additions += p.stat[0]
+          @deletions += p.stat[1]
+          @total += p.changes
+        end
+      end
+    end
+  end
+end
diff --git a/lib/gitlab/git/compare.rb b/lib/gitlab/git/compare.rb
new file mode 100644
index 00000000000..696a2acd5e3
--- /dev/null
+++ b/lib/gitlab/git/compare.rb
@@ -0,0 +1,43 @@
+module Gitlab
+  module Git
+    class Compare
+      attr_reader :head, :base, :straight
+
+      def initialize(repository, base, head, straight = false)
+        @repository = repository
+        @straight = straight
+
+        unless base && head
+          @commits = []
+          return
+        end
+
+        @base = Gitlab::Git::Commit.find(repository, base.try(:strip))
+        @head = Gitlab::Git::Commit.find(repository, head.try(:strip))
+
+        @commits = [] unless @base && @head
+        @commits = [] if same
+      end
+
+      def same
+        @base && @head && @base.id == @head.id
+      end
+
+      def commits
+        return @commits if defined?(@commits)
+
+        @commits = Gitlab::Git::Commit.between(@repository, @base.id, @head.id)
+      end
+
+      def diffs(options = {})
+        unless @head && @base
+          return Gitlab::Git::DiffCollection.new([])
+        end
+
+        paths = options.delete(:paths) || []
+        options[:straight] = @straight
+        Gitlab::Git::Diff.between(@repository, @head.id, @base.id, options, *paths)
+      end
+    end
+  end
+end
diff --git a/lib/gitlab/git/diff.rb b/lib/gitlab/git/diff.rb
new file mode 100644
index 00000000000..b8868eff6cc
--- /dev/null
+++ b/lib/gitlab/git/diff.rb
@@ -0,0 +1,322 @@
+# Gitlab::Git::Diff is a wrapper around native Rugged::Diff object
+module Gitlab
+  module Git
+    class Diff
+      class TimeoutError < StandardError; end
+      include Gitlab::Git::EncodingHelper
+
+      # Diff properties
+      attr_accessor :old_path, :new_path, :a_mode, :b_mode, :diff
+
+      # Stats properties
+      attr_accessor :new_file, :renamed_file, :deleted_file
+
+      attr_accessor :too_large
+
+      # The maximum size of a diff to display.
+      DIFF_SIZE_LIMIT = 102400 # 100 KB
+
+      # The maximum size before a diff is collapsed.
+      DIFF_COLLAPSE_LIMIT = 10240 # 10 KB
+
+      class << self
+        def between(repo, head, base, options = {}, *paths)
+          straight = options.delete(:straight) || false
+
+          common_commit = if straight
+                            base
+                          else
+                            # Only show what is new in the source branch
+                            # compared to the target branch, not the other way
+                            # around. The linex below with merge_base is
+                            # equivalent to diff with three dots (git diff
+                            # branch1...branch2) From the git documentation:
+                            # "git diff A...B" is equivalent to "git diff
+                            # $(git-merge-base A B) B"
+                            repo.merge_base_commit(head, base)
+                          end
+
+          options ||= {}
+          actual_options = filter_diff_options(options)
+          repo.diff(common_commit, head, actual_options, *paths)
+        end
+
+        # Return a copy of the +options+ hash containing only keys that can be
+        # passed to Rugged.  Allowed options are:
+        #
+        #  :max_size ::
+        #    An integer specifying the maximum byte size of a file before a it
+        #    will be treated as binary. The default value is 512MB.
+        #
+        #  :context_lines ::
+        #    The number of unchanged lines that define the boundary of a hunk
+        #    (and to display before and after the actual changes). The default is
+        #    3.
+        #
+        #  :interhunk_lines ::
+        #    The maximum number of unchanged lines between hunk boundaries before
+        #    the hunks will be merged into a one. The default is 0.
+        #
+        #  :old_prefix ::
+        #    The virtual "directory" to prefix to old filenames in hunk headers.
+        #    The default is "a".
+        #
+        #  :new_prefix ::
+        #    The virtual "directory" to prefix to new filenames in hunk headers.
+        #    The default is "b".
+        #
+        #  :reverse ::
+        #    If true, the sides of the diff will be reversed.
+        #
+        #  :force_text ::
+        #    If true, all files will be treated as text, disabling binary
+        #    attributes & detection.
+        #
+        #  :ignore_whitespace ::
+        #    If true, all whitespace will be ignored.
+        #
+        #  :ignore_whitespace_change ::
+        #    If true, changes in amount of whitespace will be ignored.
+        #
+        #  :ignore_whitespace_eol ::
+        #    If true, whitespace at end of line will be ignored.
+        #
+        #  :ignore_submodules ::
+        #    if true, submodules will be excluded from the diff completely.
+        #
+        #  :patience ::
+        #    If true, the "patience diff" algorithm will be used (currenlty
+        #    unimplemented).
+        #
+        #  :include_ignored ::
+        #    If true, ignored files will be included in the diff.
+        #
+        #  :include_untracked ::
+        #   If true, untracked files will be included in the diff.
+        #
+        #  :include_unmodified ::
+        #    If true, unmodified files will be included in the diff.
+        #
+        #  :recurse_untracked_dirs ::
+        #    Even if +:include_untracked+ is true, untracked directories will
+        #    only be marked with a single entry in the diff. If this flag is set
+        #    to true, all files under ignored directories will be included in the
+        #    diff, too.
+        #
+        #  :disable_pathspec_match ::
+        #    If true, the given +*paths+ will be applied as exact matches,
+        #    instead of as fnmatch patterns.
+        #
+        #  :deltas_are_icase ::
+        #    If true, filename comparisons will be made with case-insensitivity.
+        #
+        #  :include_untracked_content ::
+        #    if true, untracked content will be contained in the the diff patch
+        #    text.
+        #
+        #  :skip_binary_check ::
+        #    If true, diff deltas will be generated without spending time on
+        #    binary detection. This is useful to improve performance in cases
+        #    where the actual file content difference is not needed.
+        #
+        #  :include_typechange ::
+        #    If true, type changes for files will not be interpreted as deletion
+        #    of the "old file" and addition of the "new file", but will generate
+        #    typechange records.
+        #
+        #  :include_typechange_trees ::
+        #    Even if +:include_typechange+ is true, blob -> tree changes will
+        #    still usually be handled as a deletion of the blob. If this flag is
+        #    set to true, blob -> tree changes will be marked as typechanges.
+        #
+        #  :ignore_filemode ::
+        #    If true, file mode changes will be ignored.
+        #
+        #  :recurse_ignored_dirs ::
+        #    Even if +:include_ignored+ is true, ignored directories will only be
+        #    marked with a single entry in the diff. If this flag is set to true,
+        #    all files under ignored directories will be included in the diff,
+        #    too.
+        def filter_diff_options(options, default_options = {})
+          allowed_options = [:max_size, :context_lines, :interhunk_lines,
+                             :old_prefix, :new_prefix, :reverse, :force_text,
+                             :ignore_whitespace, :ignore_whitespace_change,
+                             :ignore_whitespace_eol, :ignore_submodules,
+                             :patience, :include_ignored, :include_untracked,
+                             :include_unmodified, :recurse_untracked_dirs,
+                             :disable_pathspec_match, :deltas_are_icase,
+                             :include_untracked_content, :skip_binary_check,
+                             :include_typechange, :include_typechange_trees,
+                             :ignore_filemode, :recurse_ignored_dirs, :paths,
+                             :max_files, :max_lines, :all_diffs, :no_collapse]
+
+          if default_options
+            actual_defaults = default_options.dup
+            actual_defaults.keep_if do |key|
+              allowed_options.include?(key)
+            end
+          else
+            actual_defaults = {}
+          end
+
+          if options
+            filtered_opts = options.dup
+            filtered_opts.keep_if do |key|
+              allowed_options.include?(key)
+            end
+            filtered_opts = actual_defaults.merge(filtered_opts)
+          else
+            filtered_opts = actual_defaults
+          end
+
+          filtered_opts
+        end
+      end
+
+      def initialize(raw_diff, collapse: false)
+        case raw_diff
+        when Hash
+          init_from_hash(raw_diff, collapse: collapse)
+        when Rugged::Patch, Rugged::Diff::Delta
+          init_from_rugged(raw_diff, collapse: collapse)
+        when nil
+          raise "Nil as raw diff passed"
+        else
+          raise "Invalid raw diff type: #{raw_diff.class}"
+        end
+      end
+
+      def serialize_keys
+        @serialize_keys ||= %i(diff new_path old_path a_mode b_mode new_file renamed_file deleted_file too_large)
+      end
+
+      def to_hash
+        hash = {}
+
+        keys = serialize_keys
+
+        keys.each do |key|
+          hash[key] = send(key)
+        end
+
+        hash
+      end
+
+      def submodule?
+        a_mode == '160000' || b_mode == '160000'
+      end
+
+      def line_count
+        @line_count ||= Gitlab::Git::Util.count_lines(@diff)
+      end
+
+      def too_large?
+        if @too_large.nil?
+          @too_large = @diff.bytesize >= DIFF_SIZE_LIMIT
+        else
+          @too_large
+        end
+      end
+
+      def collapsible?
+        @diff.bytesize >= DIFF_COLLAPSE_LIMIT
+      end
+
+      def prune_large_diff!
+        @diff = ''
+        @line_count = 0
+        @too_large = true
+      end
+
+      def collapsed?
+        return @collapsed if defined?(@collapsed)
+        false
+      end
+
+      def prune_collapsed_diff!
+        @diff = ''
+        @line_count = 0
+        @collapsed = true
+      end
+
+      private
+
+      def init_from_rugged(rugged, collapse: false)
+        if rugged.is_a?(Rugged::Patch)
+          init_from_rugged_patch(rugged, collapse: collapse)
+          d = rugged.delta
+        else
+          d = rugged
+        end
+
+        @new_path = encode!(d.new_file[:path])
+        @old_path = encode!(d.old_file[:path])
+        @a_mode = d.old_file[:mode].to_s(8)
+        @b_mode = d.new_file[:mode].to_s(8)
+        @new_file = d.added?
+        @renamed_file = d.renamed?
+        @deleted_file = d.deleted?
+      end
+
+      def init_from_rugged_patch(patch, collapse: false)
+        # Don't bother initializing diffs that are too large. If a diff is
+        # binary we're not going to display anything so we skip the size check.
+        return if !patch.delta.binary? && prune_large_patch(patch, collapse)
+
+        @diff = encode!(strip_diff_headers(patch.to_s))
+      end
+
+      def init_from_hash(hash, collapse: false)
+        raw_diff = hash.symbolize_keys
+
+        serialize_keys.each do |key|
+          send(:"#{key}=", raw_diff[key.to_sym])
+        end
+
+        prune_large_diff! if too_large?
+        prune_collapsed_diff! if collapse && collapsible?
+      end
+
+      # If the patch surpasses any of the diff limits it calls the appropiate
+      # prune method and returns true. Otherwise returns false.
+      def prune_large_patch(patch, collapse)
+        size = 0
+
+        patch.each_hunk do |hunk|
+          hunk.each_line do |line|
+            size += line.content.bytesize
+
+            if size >= DIFF_SIZE_LIMIT
+              prune_large_diff!
+              return true
+            end
+          end
+        end
+
+        if collapse && size >= DIFF_COLLAPSE_LIMIT
+          prune_collapsed_diff!
+          return true
+        end
+
+        false
+      end
+
+      # Strip out the information at the beginning of the patch's text to match
+      # Grit's output
+      def strip_diff_headers(diff_text)
+        # Delete everything up to the first line that starts with '---' or
+        # 'Binary'
+        diff_text.sub!(/\A.*?^(---|Binary)/m, '\1')
+
+        if diff_text.start_with?('---', 'Binary')
+          diff_text
+        else
+          # If the diff_text did not contain a line starting with '---' or
+          # 'Binary', return the empty string. No idea why; we are just
+          # preserving behavior from before the refactor.
+          ''
+        end
+      end
+    end
+  end
+end
diff --git a/lib/gitlab/git/diff_collection.rb b/lib/gitlab/git/diff_collection.rb
new file mode 100644
index 00000000000..65e06f5065d
--- /dev/null
+++ b/lib/gitlab/git/diff_collection.rb
@@ -0,0 +1,129 @@
+module Gitlab
+  module Git
+    class DiffCollection
+      include Enumerable
+
+      DEFAULT_LIMITS = { max_files: 100, max_lines: 5000 }.freeze
+
+      def initialize(iterator, options = {})
+        @iterator = iterator
+        @max_files = options.fetch(:max_files, DEFAULT_LIMITS[:max_files])
+        @max_lines = options.fetch(:max_lines, DEFAULT_LIMITS[:max_lines])
+        @max_bytes = @max_files * 5120 # Average 5 KB per file
+        @safe_max_files = [@max_files, DEFAULT_LIMITS[:max_files]].min
+        @safe_max_lines = [@max_lines, DEFAULT_LIMITS[:max_lines]].min
+        @safe_max_bytes = @safe_max_files * 5120 # Average 5 KB per file
+        @all_diffs = !!options.fetch(:all_diffs, false)
+        @no_collapse = !!options.fetch(:no_collapse, true)
+        @deltas_only = !!options.fetch(:deltas_only, false)
+
+        @line_count = 0
+        @byte_count = 0
+        @overflow = false
+        @array = Array.new
+      end
+
+      def each(&block)
+        if @populated
+          # @iterator.each is slower than just iterating the array in place
+          @array.each(&block)
+        elsif @deltas_only
+          each_delta(&block)
+        else
+          each_patch(&block)
+        end
+      end
+
+      def empty?
+        !@iterator.any?
+      end
+
+      def overflow?
+        populate!
+        !!@overflow
+      end
+
+      def size
+        @size ||= count # forces a loop using each method
+      end
+
+      def real_size
+        populate!
+
+        if @overflow
+          "#{size}+"
+        else
+          size.to_s
+        end
+      end
+
+      def decorate!
+        collection = each_with_index do |element, i|
+          @array[i] = yield(element)
+        end
+        @populated = true
+        collection
+      end
+
+      private
+
+      def populate!
+        return if @populated
+
+        each { nil } # force a loop through all diffs
+        @populated = true
+        nil
+      end
+
+      def over_safe_limits?(files)
+        files >= @safe_max_files || @line_count > @safe_max_lines || @byte_count >= @safe_max_bytes
+      end
+
+      def each_delta
+        @iterator.each_delta.with_index do |delta, i|
+          diff = Gitlab::Git::Diff.new(delta)
+
+          yield @array[i] = diff
+        end
+      end
+
+      def each_patch
+        @iterator.each_with_index do |raw, i|
+          # First yield cached Diff instances from @array
+          if @array[i]
+            yield @array[i]
+            next
+          end
+
+          # We have exhausted @array, time to create new Diff instances or stop.
+          break if @overflow
+
+          if !@all_diffs && i >= @max_files
+            @overflow = true
+            break
+          end
+
+          collapse = !@all_diffs && !@no_collapse
+
+          diff = Gitlab::Git::Diff.new(raw, collapse: collapse)
+
+          if collapse && over_safe_limits?(i)
+            diff.prune_collapsed_diff!
+          end
+
+          @line_count += diff.line_count
+          @byte_count += diff.diff.bytesize
+
+          if !@all_diffs && (@line_count >= @max_lines || @byte_count >= @max_bytes)
+            # This last Diff instance pushes us over the lines limit. We stop and
+            # discard it.
+            @overflow = true
+            break
+          end
+
+          yield @array[i] = diff
+        end
+      end
+    end
+  end
+end
diff --git a/lib/gitlab/git/encoding_helper.rb b/lib/gitlab/git/encoding_helper.rb
new file mode 100644
index 00000000000..b0a43496198
--- /dev/null
+++ b/lib/gitlab/git/encoding_helper.rb
@@ -0,0 +1,58 @@
+module Gitlab
+  module Git
+    module EncodingHelper
+      extend self
+
+      # This threshold is carefully tweaked to prevent usage of encodings detected
+      # by CharlockHolmes with low confidence. If CharlockHolmes confidence is low,
+      # we're better off sticking with utf8 encoding.
+      # Reason: git diff can return strings with invalid utf8 byte sequences if it
+      # truncates a diff in the middle of a multibyte character. In this case
+      # CharlockHolmes will try to guess the encoding and will likely suggest an
+      # obscure encoding with low confidence.
+      # There is a lot more info with this merge request:
+      # https://gitlab.com/gitlab-org/gitlab_git/merge_requests/77#note_4754193
+      ENCODING_CONFIDENCE_THRESHOLD = 40
+
+      def encode!(message)
+        return nil unless message.respond_to? :force_encoding
+
+        # if message is utf-8 encoding, just return it
+        message.force_encoding("UTF-8")
+        return message if message.valid_encoding?
+
+        # return message if message type is binary
+        detect = CharlockHolmes::EncodingDetector.detect(message)
+        return message.force_encoding("BINARY") if detect && detect[:type] == :binary
+
+        # force detected encoding if we have sufficient confidence.
+        if detect && detect[:encoding] && detect[:confidence] > ENCODING_CONFIDENCE_THRESHOLD
+          message.force_encoding(detect[:encoding])
+        end
+
+        # encode and clean the bad chars
+        message.replace clean(message)
+      rescue
+        encoding = detect ? detect[:encoding] : "unknown"
+        "--broken encoding: #{encoding}"
+      end
+
+      def encode_utf8(message)
+        detect = CharlockHolmes::EncodingDetector.detect(message)
+        if detect
+          CharlockHolmes::Converter.convert(message, detect[:encoding], 'UTF-8')
+        else
+          clean(message)
+        end
+      end
+
+      private
+
+      def clean(message)
+        message.encode("UTF-16BE", undef: :replace, invalid: :replace, replace: "")
+               .encode("UTF-8")
+               .gsub("\0".encode("UTF-8"), "")
+      end
+    end
+  end
+end
diff --git a/lib/gitlab/git/path_helper.rb b/lib/gitlab/git/path_helper.rb
new file mode 100644
index 00000000000..0148cd8df05
--- /dev/null
+++ b/lib/gitlab/git/path_helper.rb
@@ -0,0 +1,16 @@
+module Gitlab
+  module Git
+    class PathHelper
+      class << self
+        def normalize_path(filename)
+          # Strip all leading slashes so that //foo -> foo
+          filename[/^\/*/] = ''
+
+          # Expand relative paths (e.g. foo/../bar)
+          filename = Pathname.new(filename)
+          filename.relative_path_from(Pathname.new(''))
+        end
+      end
+    end
+  end
+end
diff --git a/lib/gitlab/git/popen.rb b/lib/gitlab/git/popen.rb
new file mode 100644
index 00000000000..a9a6c98aa04
--- /dev/null
+++ b/lib/gitlab/git/popen.rb
@@ -0,0 +1,24 @@
+module Gitlab
+  module Git
+    module Popen
+      def popen(cmd, path)
+        unless cmd.is_a?(Array)
+          raise "System commands must be given as an array of strings"
+        end
+
+        vars = { "PWD" => path }
+        options = { chdir: path }
+
+        @cmd_output = ""
+        @cmd_status = 0
+        Open3.popen3(vars, *cmd, options) do |stdin, stdout, stderr, wait_thr|
+          @cmd_output << stdout.read
+          @cmd_output << stderr.read
+          @cmd_status = wait_thr.value.exitstatus
+        end
+
+        [@cmd_output, @cmd_status]
+      end
+    end
+  end
+end
diff --git a/lib/gitlab/git/ref.rb b/lib/gitlab/git/ref.rb
new file mode 100644
index 00000000000..37ef6836742
--- /dev/null
+++ b/lib/gitlab/git/ref.rb
@@ -0,0 +1,49 @@
+module Gitlab
+  module Git
+    class Ref
+      include Gitlab::Git::EncodingHelper
+
+      # Branch or tag name
+      # without "refs/tags|heads" prefix
+      attr_reader :name
+
+      # Target sha.
+      # Usually it is commit sha but in case
+      # when tag reference on other tag it can be tag sha
+      attr_reader :target
+
+      # Dereferenced target
+      # Commit object to which the Ref points to
+      attr_reader :dereferenced_target
+
+      # Extract branch name from full ref path
+      #
+      # Ex.
+      #   Ref.extract_branch_name('refs/heads/master') #=> 'master'
+      def self.extract_branch_name(str)
+        str.gsub(/\Arefs\/heads\//, '')
+      end
+
+      def self.dereference_object(object)
+        object = object.target while object.is_a?(Rugged::Tag::Annotation)
+
+        object
+      end
+
+      def initialize(repository, name, target)
+        encode! name
+        @name = name.gsub(/\Arefs\/(tags|heads)\//, '')
+        @dereferenced_target = Gitlab::Git::Commit.find(repository, target)
+        @target = if target.respond_to?(:oid)
+                    target.oid
+                  elsif target.respond_to?(:name)
+                    target.name
+                  elsif target.is_a? String
+                    target
+                  else
+                    nil
+                  end
+      end
+    end
+  end
+end
diff --git a/lib/gitlab/git/repository.rb b/lib/gitlab/git/repository.rb
new file mode 100644
index 00000000000..699e0ef2d64
--- /dev/null
+++ b/lib/gitlab/git/repository.rb
@@ -0,0 +1,1257 @@
+# Gitlab::Git::Repository is a wrapper around native Rugged::Repository object
+module Gitlab
+  module Git
+    class Repository
+      extend Forwardable
+      include Gitlab::Git::Popen
+
+      SEARCH_CONTEXT_LINES = 3
+
+      class NoRepository < StandardError; end
+      class InvalidBlobName < StandardError; end
+      class InvalidRef < StandardError; end
+
+      # Full path to repo
+      attr_reader :path
+
+      # Directory name of repo
+      attr_reader :name
+
+      # Rugged repo object
+      attr_reader :rugged
+
+      # 'path' must be the path to a _bare_ git repository, e.g.
+      # /path/to/my-repo.git
+      def initialize(path)
+        @path = path
+        @name = path.split("/").last
+        @attributes = Attributes.new(path)
+      end
+
+      # Default branch in the repository
+      def root_ref
+        @root_ref ||= discover_default_branch
+      end
+
+      # Alias to old method for compatibility
+      def raw
+        rugged
+      end
+
+      def rugged
+        @rugged ||= Rugged::Repository.new(path)
+      rescue Rugged::RepositoryError, Rugged::OSError
+        raise NoRepository.new('no repository for such path')
+      end
+
+      # Returns an Array of branch names
+      # sorted by name ASC
+      def branch_names
+        branches.map(&:name)
+      end
+
+      # Returns an Array of Branches
+      def branches
+        rugged.branches.map do |rugged_ref|
+          begin
+            Gitlab::Git::Branch.new(self, rugged_ref.name, rugged_ref.target)
+          rescue Rugged::ReferenceError
+            # Omit invalid branch
+          end
+        end.compact.sort_by(&:name)
+      end
+
+      def reload_rugged
+        @rugged = nil
+      end
+
+      # Directly find a branch with a simple name (e.g. master)
+      #
+      # force_reload causes a new Rugged repository to be instantiated
+      #
+      # This is to work around a bug in libgit2 that causes in-memory refs to
+      # be stale/invalid when packed-refs is changed.
+      # See https://gitlab.com/gitlab-org/gitlab-ce/issues/15392#note_14538333
+      def find_branch(name, force_reload = false)
+        reload_rugged if force_reload
+
+        rugged_ref = rugged.branches[name]
+        Gitlab::Git::Branch.new(self, rugged_ref.name, rugged_ref.target) if rugged_ref
+      end
+
+      def local_branches
+        rugged.branches.each(:local).map do |branch|
+          Gitlab::Git::Branch.new(self, branch.name, branch.target)
+        end
+      end
+
+      # Returns the number of valid branches
+      def branch_count
+        rugged.branches.count do |ref|
+          begin
+            ref.name && ref.target # ensures the branch is valid
+
+            true
+          rescue Rugged::ReferenceError
+            false
+          end
+        end
+      end
+
+      # Returns an Array of tag names
+      def tag_names
+        rugged.tags.map { |t| t.name }
+      end
+
+      # Returns an Array of Tags
+      def tags
+        rugged.references.each("refs/tags/*").map do |ref|
+          message = nil
+
+          if ref.target.is_a?(Rugged::Tag::Annotation)
+            tag_message = ref.target.message
+
+            if tag_message.respond_to?(:chomp)
+              message = tag_message.chomp
+            end
+          end
+
+          Gitlab::Git::Tag.new(self, ref.name, ref.target, message)
+        end.sort_by(&:name)
+      end
+
+      # Returns true if the given tag exists
+      #
+      # name - The name of the tag as a String.
+      def tag_exists?(name)
+        !!rugged.tags[name]
+      end
+
+      # Returns true if the given branch exists
+      #
+      # name - The name of the branch as a String.
+      def branch_exists?(name)
+        rugged.branches.exists?(name)
+
+      # If the branch name is invalid (e.g. ".foo") Rugged will raise an error.
+      # Whatever code calls this method shouldn't have to deal with that so
+      # instead we just return `false` (which is true since a branch doesn't
+      # exist when it has an invalid name).
+      rescue Rugged::ReferenceError
+        false
+      end
+
+      # Returns an Array of branch and tag names
+      def ref_names
+        branch_names + tag_names
+      end
+
+      # Deprecated. Will be removed in 5.2
+      def heads
+        rugged.references.each("refs/heads/*").map do |head|
+          Gitlab::Git::Ref.new(self, head.name, head.target)
+        end.sort_by(&:name)
+      end
+
+      def has_commits?
+        !empty?
+      end
+
+      def empty?
+        rugged.empty?
+      end
+
+      def bare?
+        rugged.bare?
+      end
+
+      def repo_exists?
+        !!rugged
+      end
+
+      # Discovers the default branch based on the repository's available branches
+      #
+      # - If no branches are present, returns nil
+      # - If one branch is present, returns its name
+      # - If two or more branches are present, returns current HEAD or master or first branch
+      def discover_default_branch
+        names = branch_names
+
+        return if names.empty?
+
+        return names[0] if names.length == 1
+
+        if rugged_head
+          extracted_name = Gitlab::Git::Ref.extract_branch_name(rugged_head.name)
+
+          return extracted_name if names.include?(extracted_name)
+        end
+
+        if names.include?('master')
+          'master'
+        else
+          names[0]
+        end
+      end
+
+      def rugged_head
+        rugged.head
+      rescue Rugged::ReferenceError
+        nil
+      end
+
+      def archive_metadata(ref, storage_path, format = "tar.gz")
+        ref ||= root_ref
+        commit = Gitlab::Git::Commit.find(self, ref)
+        return {} if commit.nil?
+
+        project_name = self.name.chomp('.git')
+        prefix = "#{project_name}-#{ref}-#{commit.id}"
+
+        {
+          'RepoPath' => path,
+          'ArchivePrefix' => prefix,
+          'ArchivePath' => archive_file_path(prefix, storage_path, format),
+          'CommitId' => commit.id,
+        }
+      end
+
+      def archive_file_path(name, storage_path, format = "tar.gz")
+        # Build file path
+        return nil unless name
+
+        extension =
+          case format
+          when "tar.bz2", "tbz", "tbz2", "tb2", "bz2"
+            "tar.bz2"
+          when "tar"
+            "tar"
+          when "zip"
+            "zip"
+          else
+            # everything else should fall back to tar.gz
+            "tar.gz"
+          end
+
+        file_name = "#{name}.#{extension}"
+        File.join(storage_path, self.name, file_name)
+      end
+
+      # Return repo size in megabytes
+      def size
+        size = popen(%w(du -sk), path).first.strip.to_i
+        (size.to_f / 1024).round(2)
+      end
+
+      # Returns an array of BlobSnippets for files at the specified +ref+ that
+      # contain the +query+ string.
+      def search_files(query, ref = nil)
+        greps = []
+        ref ||= root_ref
+
+        populated_index(ref).each do |entry|
+          # Discard submodules
+          next if submodule?(entry)
+
+          blob = Gitlab::Git::Blob.raw(self, entry[:oid])
+
+          # Skip binary files
+          next if blob.data.encoding == Encoding::ASCII_8BIT
+
+          blob.load_all_data!(self)
+          greps += build_greps(blob.data, query, ref, entry[:path])
+        end
+
+        greps
+      end
+
+      # Use the Rugged Walker API to build an array of commits.
+      #
+      # Usage.
+      #   repo.log(
+      #     ref: 'master',
+      #     path: 'app/models',
+      #     limit: 10,
+      #     offset: 5,
+      #     after: Time.new(2016, 4, 21, 14, 32, 10)
+      #   )
+      #
+      def log(options)
+        default_options = {
+          limit: 10,
+          offset: 0,
+          path: nil,
+          follow: false,
+          skip_merges: false,
+          disable_walk: false,
+          after: nil,
+          before: nil
+        }
+
+        options = default_options.merge(options)
+        options[:limit] ||= 0
+        options[:offset] ||= 0
+        actual_ref = options[:ref] || root_ref
+        begin
+          sha = sha_from_ref(actual_ref)
+        rescue Rugged::OdbError, Rugged::InvalidError, Rugged::ReferenceError
+          # Return an empty array if the ref wasn't found
+          return []
+        end
+
+        if log_using_shell?(options)
+          log_by_shell(sha, options)
+        else
+          log_by_walk(sha, options)
+        end
+      end
+
+      def log_using_shell?(options)
+        options[:path].present? ||
+          options[:disable_walk] ||
+          options[:skip_merges] ||
+          options[:after] ||
+          options[:before]
+      end
+
+      def log_by_walk(sha, options)
+        walk_options = {
+          show: sha,
+          sort: Rugged::SORT_DATE,
+          limit: options[:limit],
+          offset: options[:offset]
+        }
+        Rugged::Walker.walk(rugged, walk_options).to_a
+      end
+
+      def log_by_shell(sha, options)
+        cmd = %W(git --git-dir=#{path} log)
+        cmd += %W(-n #{options[:limit].to_i})
+        cmd += %w(--format=%H)
+        cmd += %W(--skip=#{options[:offset].to_i})
+        cmd += %w(--follow) if options[:follow]
+        cmd += %w(--no-merges) if options[:skip_merges]
+        cmd += %W(--after=#{options[:after].iso8601}) if options[:after]
+        cmd += %W(--before=#{options[:before].iso8601}) if options[:before]
+        cmd += [sha]
+        cmd += %W(-- #{options[:path]}) if options[:path].present?
+
+        raw_output = IO.popen(cmd) {|io| io.read }
+
+        log = raw_output.lines.map do |c|
+          Rugged::Commit.new(rugged, c.strip)
+        end
+
+        log.is_a?(Array) ? log : []
+      end
+
+      def sha_from_ref(ref)
+        rev_parse_target(ref).oid
+      end
+
+      # Return the object that +revspec+ points to.  If +revspec+ is an
+      # annotated tag, then return the tag's target instead.
+      def rev_parse_target(revspec)
+        obj = rugged.rev_parse(revspec)
+        Gitlab::Git::Ref.dereference_object(obj)
+      end
+
+      # Return a collection of Rugged::Commits between the two revspec arguments.
+      # See http://git-scm.com/docs/git-rev-parse.html#_specifying_revisions for
+      # a detailed list of valid arguments.
+      def commits_between(from, to)
+        walker = Rugged::Walker.new(rugged)
+        walker.sorting(Rugged::SORT_DATE | Rugged::SORT_REVERSE)
+
+        sha_from = sha_from_ref(from)
+        sha_to = sha_from_ref(to)
+
+        walker.push(sha_to)
+        walker.hide(sha_from)
+
+        commits = walker.to_a
+        walker.reset
+
+        commits
+      end
+
+      # Counts the amount of commits between `from` and `to`.
+      def count_commits_between(from, to)
+        commits_between(from, to).size
+      end
+
+      # Returns the SHA of the most recent common ancestor of +from+ and +to+
+      def merge_base_commit(from, to)
+        rugged.merge_base(from, to)
+      end
+
+      # Return an array of Diff objects that represent the diff
+      # between +from+ and +to+.  See Diff::filter_diff_options for the allowed
+      # diff options.  The +options+ hash can also include :break_rewrites to
+      # split larger rewrites into delete/add pairs.
+      def diff(from, to, options = {}, *paths)
+        Gitlab::Git::DiffCollection.new(diff_patches(from, to, options, *paths), options)
+      end
+
+      # Return the diff between +from+ and +to+ in a single patch string.  The
+      # +options+ hash has the same allowed keys as #diff.
+      def diff_text(from, to, options = {}, *paths)
+        # NOTE: It would be simpler to use the Rugged::Diff#patch method, but
+        # that formats the diff text differently than Rugged::Patch#to_s for
+        # changes to binary files.
+        diff_patches(from, to, options, *paths).map do |p|
+          p.to_s
+        end.join("\n")
+      end
+
+      # Returns commits collection
+      #
+      # Ex.
+      #   repo.find_commits(
+      #     ref: 'master',
+      #     max_count: 10,
+      #     skip: 5,
+      #     order: :date
+      #   )
+      #
+      #   +options+ is a Hash of optional arguments to git
+      #     :ref is the ref from which to begin (SHA1 or name)
+      #     :contains is the commit contained by the refs from which to begin (SHA1 or name)
+      #     :max_count is the maximum number of commits to fetch
+      #     :skip is the number of commits to skip
+      #     :order is the commits order and allowed value is :date(default) or :topo
+      #
+      def find_commits(options = {})
+        actual_options = options.dup
+
+        allowed_options = [:ref, :max_count, :skip, :contains, :order]
+
+        actual_options.keep_if do |key|
+          allowed_options.include?(key)
+        end
+
+        default_options = { skip: 0 }
+        actual_options = default_options.merge(actual_options)
+
+        walker = Rugged::Walker.new(rugged)
+
+        if actual_options[:ref]
+          walker.push(rugged.rev_parse_oid(actual_options[:ref]))
+        elsif actual_options[:contains]
+          branches_contains(actual_options[:contains]).each do |branch|
+            walker.push(branch.target_id)
+          end
+        else
+          rugged.references.each("refs/heads/*") do |ref|
+            walker.push(ref.target_id)
+          end
+        end
+
+        if actual_options[:order] == :topo
+          walker.sorting(Rugged::SORT_TOPO)
+        else
+          walker.sorting(Rugged::SORT_DATE)
+        end
+
+        commits = []
+        offset = actual_options[:skip]
+        limit = actual_options[:max_count]
+        walker.each(offset: offset, limit: limit) do |commit|
+          gitlab_commit = Gitlab::Git::Commit.decorate(commit)
+          commits.push(gitlab_commit)
+        end
+
+        walker.reset
+
+        commits
+      rescue Rugged::OdbError
+        []
+      end
+
+      # Returns branch names collection that contains the special commit(SHA1
+      # or name)
+      #
+      # Ex.
+      #   repo.branch_names_contains('master')
+      #
+      def branch_names_contains(commit)
+        branches_contains(commit).map { |c| c.name }
+      end
+
+      # Returns branch collection that contains the special commit(SHA1 or name)
+      #
+      # Ex.
+      #   repo.branch_names_contains('master')
+      #
+      def branches_contains(commit)
+        commit_obj = rugged.rev_parse(commit)
+        parent = commit_obj.parents.first unless commit_obj.parents.empty?
+
+        walker = Rugged::Walker.new(rugged)
+
+        rugged.branches.select do |branch|
+          walker.push(branch.target_id)
+          walker.hide(parent) if parent
+          result = walker.any? { |c| c.oid == commit_obj.oid }
+          walker.reset
+
+          result
+        end
+      end
+
+      # Get refs hash which key is SHA1
+      # and value is a Rugged::Reference
+      def refs_hash
+        # Initialize only when first call
+        if @refs_hash.nil?
+          @refs_hash = Hash.new { |h, k| h[k] = [] }
+
+          rugged.references.each do |r|
+            # Symbolic/remote references may not have an OID; skip over them
+            target_oid = r.target.try(:oid)
+            if target_oid
+              sha = rev_parse_target(target_oid).oid
+              @refs_hash[sha] << r
+            end
+          end
+        end
+        @refs_hash
+      end
+
+      # Lookup for rugged object by oid or ref name
+      def lookup(oid_or_ref_name)
+        rugged.rev_parse(oid_or_ref_name)
+      end
+
+      # Return hash with submodules info for this repository
+      #
+      # Ex.
+      #   {
+      #     "rack"  => {
+      #       "id" => "c67be4624545b4263184c4a0e8f887efd0a66320",
+      #       "path" => "rack",
+      #       "url" => "git://github.com/chneukirchen/rack.git"
+      #     },
+      #     "encoding" => {
+      #       "id" => ....
+      #     }
+      #   }
+      #
+      def submodules(ref)
+        commit = rev_parse_target(ref)
+        return {} unless commit
+
+        begin
+          content = blob_content(commit, ".gitmodules")
+        rescue InvalidBlobName
+          return {}
+        end
+
+        parse_gitmodules(commit, content)
+      end
+
+      # Return total commits count accessible from passed ref
+      def commit_count(ref)
+        walker = Rugged::Walker.new(rugged)
+        walker.sorting(Rugged::SORT_TOPO | Rugged::SORT_REVERSE)
+        oid = rugged.rev_parse_oid(ref)
+        walker.push(oid)
+        walker.count
+      end
+
+      # Sets HEAD to the commit specified by +ref+; +ref+ can be a branch or
+      # tag name or a commit SHA.  Valid +reset_type+ values are:
+      #
+      #  [:soft]
+      #    the head will be moved to the commit.
+      #  [:mixed]
+      #    will trigger a +:soft+ reset, plus the index will be replaced
+      #    with the content of the commit tree.
+      #  [:hard]
+      #    will trigger a +:mixed+ reset and the working directory will be
+      #    replaced with the content of the index. (Untracked and ignored files
+      #    will be left alone)
+      def reset(ref, reset_type)
+        rugged.reset(ref, reset_type)
+      end
+
+      # Mimic the `git clean` command and recursively delete untracked files.
+      # Valid keys that can be passed in the +options+ hash are:
+      #
+      # :d - Remove untracked directories
+      # :f - Remove untracked directories that are managed by a different
+      #      repository
+      # :x - Remove ignored files
+      #
+      # The value in +options+ must evaluate to true for an option to take
+      # effect.
+      #
+      # Examples:
+      #
+      #   repo.clean(d: true, f: true) # Enable the -d and -f options
+      #
+      #   repo.clean(d: false, x: true) # -x is enabled, -d is not
+      def clean(options = {})
+        strategies = [:remove_untracked]
+        strategies.push(:force) if options[:f]
+        strategies.push(:remove_ignored) if options[:x]
+
+        # TODO: implement this method
+      end
+
+      # Check out the specified ref. Valid options are:
+      #
+      #  :b - Create a new branch at +start_point+ and set HEAD to the new
+      #       branch.
+      #
+      #  * These options are passed to the Rugged::Repository#checkout method:
+      #
+      #  :progress ::
+      #    A callback that will be executed for checkout progress notifications.
+      #    Up to 3 parameters are passed on each execution:
+      #
+      #    - The path to the last updated file (or +nil+ on the very first
+      #      invocation).
+      #    - The number of completed checkout steps.
+      #    - The number of total checkout steps to be performed.
+      #
+      #  :notify ::
+      #    A callback that will be executed for each checkout notification
+      #    types specified with +:notify_flags+. Up to 5 parameters are passed
+      #    on each execution:
+      #
+      #    - An array containing the +:notify_flags+ that caused the callback
+      #      execution.
+      #    - The path of the current file.
+      #    - A hash describing the baseline blob (or +nil+ if it does not
+      #      exist).
+      #    - A hash describing the target blob (or +nil+ if it does not exist).
+      #    - A hash describing the workdir blob (or +nil+ if it does not
+      #      exist).
+      #
+      #  :strategy ::
+      #    A single symbol or an array of symbols representing the strategies
+      #    to use when performing the checkout. Possible values are:
+      #
+      #    :none ::
+      #      Perform a dry run (default).
+      #
+      #    :safe ::
+      #      Allow safe updates that cannot overwrite uncommitted data.
+      #
+      #    :safe_create ::
+      #      Allow safe updates plus creation of missing files.
+      #
+      #    :force ::
+      #      Allow all updates to force working directory to look like index.
+      #
+      #    :allow_conflicts ::
+      #      Allow checkout to make safe updates even if conflicts are found.
+      #
+      #    :remove_untracked ::
+      #      Remove untracked files not in index (that are not ignored).
+      #
+      #    :remove_ignored ::
+      #      Remove ignored files not in index.
+      #
+      #    :update_only ::
+      #      Only update existing files, don't create new ones.
+      #
+      #    :dont_update_index ::
+      #      Normally checkout updates index entries as it goes; this stops
+      #      that.
+      #
+      #    :no_refresh ::
+      #      Don't refresh index/config/etc before doing checkout.
+      #
+      #    :disable_pathspec_match ::
+      #      Treat pathspec as simple list of exact match file paths.
+      #
+      #    :skip_locked_directories ::
+      #      Ignore directories in use, they will be left empty.
+      #
+      #    :skip_unmerged ::
+      #      Allow checkout to skip unmerged files (NOT IMPLEMENTED).
+      #
+      #    :use_ours ::
+      #      For unmerged files, checkout stage 2 from index (NOT IMPLEMENTED).
+      #
+      #    :use_theirs ::
+      #      For unmerged files, checkout stage 3 from index (NOT IMPLEMENTED).
+      #
+      #    :update_submodules ::
+      #      Recursively checkout submodules with same options (NOT
+      #      IMPLEMENTED).
+      #
+      #    :update_submodules_if_changed ::
+      #      Recursively checkout submodules if HEAD moved in super repo (NOT
+      #      IMPLEMENTED).
+      #
+      #  :disable_filters ::
+      #    If +true+, filters like CRLF line conversion will be disabled.
+      #
+      #  :dir_mode ::
+      #    Mode for newly created directories. Default: +0755+.
+      #
+      #  :file_mode ::
+      #    Mode for newly created files. Default: +0755+ or +0644+.
+      #
+      #  :file_open_flags ::
+      #    Mode for opening files. Default:
+      #    <code>IO::CREAT | IO::TRUNC | IO::WRONLY</code>.
+      #
+      #  :notify_flags ::
+      #    A single symbol or an array of symbols representing the cases in
+      #    which the +:notify+ callback should be invoked. Possible values are:
+      #
+      #    :none ::
+      #      Do not invoke the +:notify+ callback (default).
+      #
+      #    :conflict ::
+      #      Invoke the callback for conflicting paths.
+      #
+      #    :dirty ::
+      #      Invoke the callback for "dirty" files, i.e. those that do not need
+      #      an update but no longer match the baseline.
+      #
+      #    :updated ::
+      #      Invoke the callback for any file that was changed.
+      #
+      #    :untracked ::
+      #      Invoke the callback for untracked files.
+      #
+      #    :ignored ::
+      #      Invoke the callback for ignored files.
+      #
+      #    :all ::
+      #      Invoke the callback for all these cases.
+      #
+      #  :paths ::
+      #    A glob string or an array of glob strings specifying which paths
+      #    should be taken into account for the checkout operation. +nil+ will
+      #    match all files.  Default: +nil+.
+      #
+      #  :baseline ::
+      #    A Rugged::Tree that represents the current, expected contents of the
+      #    workdir.  Default: +HEAD+.
+      #
+      #  :target_directory ::
+      #    A path to an alternative workdir directory in which the checkout
+      #    should be performed.
+      def checkout(ref, options = {}, start_point = "HEAD")
+        if options[:b]
+          rugged.branches.create(ref, start_point)
+          options.delete(:b)
+        end
+        default_options = { strategy: [:recreate_missing, :safe] }
+        rugged.checkout(ref, default_options.merge(options))
+      end
+
+      # Delete the specified branch from the repository
+      def delete_branch(branch_name)
+        rugged.branches.delete(branch_name)
+      end
+
+      # Create a new branch named **ref+ based on **stat_point+, HEAD by default
+      #
+      # Examples:
+      #   create_branch("feature")
+      #   create_branch("other-feature", "master")
+      def create_branch(ref, start_point = "HEAD")
+        rugged_ref = rugged.branches.create(ref, start_point)
+        Gitlab::Git::Branch.new(self, rugged_ref.name, rugged_ref.target)
+      rescue Rugged::ReferenceError => e
+        raise InvalidRef.new("Branch #{ref} already exists") if e.to_s =~ /'refs\/heads\/#{ref}'/
+        raise InvalidRef.new("Invalid reference #{start_point}")
+      end
+
+      # Return an array of this repository's remote names
+      def remote_names
+        rugged.remotes.each_name.to_a
+      end
+
+      # Delete the specified remote from this repository.
+      def remote_delete(remote_name)
+        rugged.remotes.delete(remote_name)
+      end
+
+      # Add a new remote to this repository.  Returns a Rugged::Remote object
+      def remote_add(remote_name, url)
+        rugged.remotes.create(remote_name, url)
+      end
+
+      # Update the specified remote using the values in the +options+ hash
+      #
+      # Example
+      # repo.update_remote("origin", url: "path/to/repo")
+      def remote_update(remote_name, options = {})
+        # TODO: Implement other remote options
+        rugged.remotes.set_url(remote_name, options[:url]) if options[:url]
+      end
+
+      # Fetch the specified remote
+      def fetch(remote_name)
+        rugged.remotes[remote_name].fetch
+      end
+
+      # Push +*refspecs+ to the remote identified by +remote_name+.
+      def push(remote_name, *refspecs)
+        rugged.remotes[remote_name].push(refspecs)
+      end
+
+      # Merge the +source_name+ branch into the +target_name+ branch. This is
+      # equivalent to `git merge --no_ff +source_name+`, since a merge commit
+      # is always created.
+      def merge(source_name, target_name, options = {})
+        our_commit = rugged.branches[target_name].target
+        their_commit = rugged.branches[source_name].target
+
+        raise "Invalid merge target" if our_commit.nil?
+        raise "Invalid merge source" if their_commit.nil?
+
+        merge_index = rugged.merge_commits(our_commit, their_commit)
+        return false if merge_index.conflicts?
+
+        actual_options = options.merge(
+          parents: [our_commit, their_commit],
+          tree: merge_index.write_tree(rugged),
+          update_ref: "refs/heads/#{target_name}"
+        )
+        Rugged::Commit.create(rugged, actual_options)
+      end
+
+      def commits_since(from_date)
+        walker = Rugged::Walker.new(rugged)
+        walker.sorting(Rugged::SORT_DATE | Rugged::SORT_REVERSE)
+
+        rugged.references.each("refs/heads/*") do |ref|
+          walker.push(ref.target_id)
+        end
+
+        commits = []
+        walker.each do |commit|
+          break if commit.author[:time].to_date < from_date
+          commits.push(commit)
+        end
+
+        commits
+      end
+
+      AUTOCRLF_VALUES = {
+        "true" => true,
+        "false" => false,
+        "input" => :input
+      }.freeze
+
+      def autocrlf
+        AUTOCRLF_VALUES[rugged.config['core.autocrlf']]
+      end
+
+      def autocrlf=(value)
+        rugged.config['core.autocrlf'] = AUTOCRLF_VALUES.invert[value]
+      end
+
+      # Create a new directory with a .gitkeep file. Creates
+      # all required nested directories (i.e. mkdir -p behavior)
+      #
+      # options should contain next structure:
+      #   author: {
+      #     email: 'user@example.com',
+      #     name: 'Test User',
+      #     time: Time.now
+      #   },
+      #   committer: {
+      #     email: 'user@example.com',
+      #     name: 'Test User',
+      #     time: Time.now
+      #   },
+      #   commit: {
+      #     message: 'Wow such commit',
+      #     branch: 'master',
+      #     update_ref: false
+      #   }
+      def mkdir(path, options = {})
+        # Check if this directory exists; if it does, then don't bother
+        # adding .gitkeep file.
+        ref = options[:commit][:branch]
+        path = Gitlab::Git::PathHelper.normalize_path(path).to_s
+        rugged_ref = rugged.ref(ref)
+
+        raise InvalidRef.new("Invalid ref") if rugged_ref.nil?
+
+        target_commit = rugged_ref.target
+
+        raise InvalidRef.new("Invalid target commit") if target_commit.nil?
+
+        entry = tree_entry(target_commit, path)
+
+        if entry
+          if entry[:type] == :blob
+            raise InvalidBlobName.new("Directory already exists as a file")
+          else
+            raise InvalidBlobName.new("Directory already exists")
+          end
+        end
+
+        options[:file] = {
+          content: '',
+          path: "#{path}/.gitkeep",
+          update: true
+        }
+
+        Gitlab::Git::Blob.commit(self, options)
+      end
+
+      # Returns result like "git ls-files" , recursive and full file path
+      #
+      # Ex.
+      #   repo.ls_files('master')
+      #
+      def ls_files(ref)
+        actual_ref = ref || root_ref
+
+        begin
+          sha_from_ref(actual_ref)
+        rescue Rugged::OdbError, Rugged::InvalidError, Rugged::ReferenceError
+          # Return an empty array if the ref wasn't found
+          return []
+        end
+
+        cmd = %W(git --git-dir=#{path} ls-tree)
+        cmd += %w(-r)
+        cmd += %w(--full-tree)
+        cmd += %w(--full-name)
+        cmd += %W(-- #{actual_ref})
+
+        raw_output = IO.popen(cmd, &:read).split("\n").map do |f|
+          stuff, path = f.split("\t")
+          _mode, type, _sha = stuff.split(" ")
+          path if type == "blob"
+          # Contain only blob type
+        end
+
+        raw_output.compact
+      end
+
+      def copy_gitattributes(ref)
+        begin
+          commit = lookup(ref)
+        rescue Rugged::ReferenceError
+          raise InvalidRef.new("Ref #{ref} is invalid")
+        end
+
+        # Create the paths
+        info_dir_path = File.join(path, 'info')
+        info_attributes_path = File.join(info_dir_path, 'attributes')
+
+        begin
+          # Retrieve the contents of the blob
+          gitattributes_content = blob_content(commit, '.gitattributes')
+        rescue InvalidBlobName
+          # No .gitattributes found. Should now remove any info/attributes and return
+          File.delete(info_attributes_path) if File.exist?(info_attributes_path)
+          return
+        end
+
+        # Create the info directory if needed
+        Dir.mkdir(info_dir_path) unless File.directory?(info_dir_path)
+
+        # Write the contents of the .gitattributes file to info/attributes
+        # Use binary mode to prevent Rails from converting ASCII-8BIT to UTF-8
+        File.open(info_attributes_path, "wb") do |file|
+          file.write(gitattributes_content)
+        end
+      end
+
+      # Checks if the blob should be diffable according to its attributes
+      def diffable?(blob)
+        attributes(blob.path).fetch('diff') { blob.text? }
+      end
+
+      # Returns the Git attributes for the given file path.
+      #
+      # See `Gitlab::Git::Attributes` for more information.
+      def attributes(path)
+        @attributes.attributes(path)
+      end
+
+      private
+
+      # Get the content of a blob for a given commit.  If the blob is a commit
+      # (for submodules) then return the blob's OID.
+      def blob_content(commit, blob_name)
+        blob_entry = tree_entry(commit, blob_name)
+
+        unless blob_entry
+          raise InvalidBlobName.new("Invalid blob name: #{blob_name}")
+        end
+
+        case blob_entry[:type]
+        when :commit
+          blob_entry[:oid]
+        when :tree
+          raise InvalidBlobName.new("#{blob_name} is a tree, not a blob")
+        when :blob
+          rugged.lookup(blob_entry[:oid]).content
+        end
+      end
+
+      # Parses the contents of a .gitmodules file and returns a hash of
+      # submodule information.
+      def parse_gitmodules(commit, content)
+        results = {}
+
+        current = ""
+        content.split("\n").each do |txt|
+          if txt =~ /^\s*\[/
+            current = txt.match(/(?<=").*(?=")/)[0]
+            results[current] = {}
+          else
+            next unless results[current]
+            match_data = txt.match(/(\w+)\s*=\s*(.*)/)
+            next unless match_data
+            target = match_data[2].chomp
+            results[current][match_data[1]] = target
+
+            if match_data[1] == "path"
+              begin
+                results[current]["id"] = blob_content(commit, target)
+              rescue InvalidBlobName
+                results.delete(current)
+              end
+            end
+          end
+        end
+
+        results
+      end
+
+      # Returns true if +commit+ introduced changes to +path+, using commit
+      # trees to make that determination.  Uses the history simplification
+      # rules that `git log` uses by default, where a commit is omitted if it
+      # is TREESAME to any parent.
+      #
+      # If the +follow+ option is true and the file specified by +path+ was
+      # renamed, then the path value is set to the old path.
+      def commit_touches_path?(commit, path, follow, walker)
+        entry = tree_entry(commit, path)
+
+        if commit.parents.empty?
+          # This is the root commit, return true if it has +path+ in its tree
+          return !entry.nil?
+        end
+
+        num_treesame = 0
+        commit.parents.each do |parent|
+          parent_entry = tree_entry(parent, path)
+
+          # Only follow the first TREESAME parent for merge commits
+          if num_treesame > 0
+            walker.hide(parent)
+            next
+          end
+
+          if entry.nil? && parent_entry.nil?
+            num_treesame += 1
+          elsif entry && parent_entry && entry[:oid] == parent_entry[:oid]
+            num_treesame += 1
+          end
+        end
+
+        case num_treesame
+        when 0
+          detect_rename(commit, commit.parents.first, path) if follow
+          true
+        else false
+        end
+      end
+
+      # Find the entry for +path+ in the tree for +commit+
+      def tree_entry(commit, path)
+        pathname = Pathname.new(path)
+        first = true
+        tmp_entry = nil
+
+        pathname.each_filename do |dir|
+          if first
+            tmp_entry = commit.tree[dir]
+            first = false
+          elsif tmp_entry.nil?
+            return nil
+          else
+            tmp_entry = rugged.lookup(tmp_entry[:oid])
+            return nil unless tmp_entry.type == :tree
+            tmp_entry = tmp_entry[dir]
+          end
+        end
+
+        tmp_entry
+      end
+
+      # Compare +commit+ and +parent+ for +path+.  If +path+ is a file and was
+      # renamed in +commit+, then set +path+ to the old filename.
+      def detect_rename(commit, parent, path)
+        diff = parent.diff(commit, paths: [path], disable_pathspec_match: true)
+
+        # If +path+ is a filename, not a directory, then we should only have
+        # one delta.  We don't need to follow renames for directories.
+        return nil if diff.each_delta.count > 1
+
+        delta = diff.each_delta.first
+        if delta.added?
+          full_diff = parent.diff(commit)
+          full_diff.find_similar!
+
+          full_diff.each_delta do |full_delta|
+            if full_delta.renamed? && path == full_delta.new_file[:path]
+              # Look for the old path in ancestors
+              path.replace(full_delta.old_file[:path])
+            end
+          end
+        end
+      end
+
+      def archive_to_file(treeish = 'master', filename = 'archive.tar.gz', format = nil, compress_cmd = %w(gzip -n))
+        git_archive_cmd = %W(git --git-dir=#{path} archive)
+
+        # Put files into a directory before archiving
+        prefix = "#{archive_name(treeish)}/"
+        git_archive_cmd << "--prefix=#{prefix}"
+
+        # Format defaults to tar
+        git_archive_cmd << "--format=#{format}" if format
+
+        git_archive_cmd += %W(-- #{treeish})
+
+        open(filename, 'w') do |file|
+          # Create a pipe to act as the '|' in 'git archive ... | gzip'
+          pipe_rd, pipe_wr = IO.pipe
+
+          # Get the compression process ready to accept data from the read end
+          # of the pipe
+          compress_pid = spawn(*nice(compress_cmd), in: pipe_rd, out: file)
+          # The read end belongs to the compression process now; we should
+          # close our file descriptor for it.
+          pipe_rd.close
+
+          # Start 'git archive' and tell it to write into the write end of the
+          # pipe.
+          git_archive_pid = spawn(*nice(git_archive_cmd), out: pipe_wr)
+          # The write end belongs to 'git archive' now; close it.
+          pipe_wr.close
+
+          # When 'git archive' and the compression process are finished, we are
+          # done.
+          Process.waitpid(git_archive_pid)
+          raise "#{git_archive_cmd.join(' ')} failed" unless $?.success?
+          Process.waitpid(compress_pid)
+          raise "#{compress_cmd.join(' ')} failed" unless $?.success?
+        end
+      end
+
+      def nice(cmd)
+        nice_cmd = %w(nice -n 20)
+        unless unsupported_platform?
+          nice_cmd += %w(ionice -c 2 -n 7)
+        end
+        nice_cmd + cmd
+      end
+
+      def unsupported_platform?
+        %w[darwin freebsd solaris].map { |platform| RUBY_PLATFORM.include?(platform) }.any?
+      end
+
+      # Returns true if the index entry has the special file mode that denotes
+      # a submodule.
+      def submodule?(index_entry)
+        index_entry[:mode] == 57344
+      end
+
+      # Return a Rugged::Index that has read from the tree at +ref_name+
+      def populated_index(ref_name)
+        commit = rev_parse_target(ref_name)
+        index = rugged.index
+        index.read_tree(commit.tree)
+        index
+      end
+
+      # Return an array of BlobSnippets for lines in +file_contents+ that match
+      # +query+
+      def build_greps(file_contents, query, ref, filename)
+        # The file_contents string is potentially huge so we make sure to loop
+        # through it one line at a time. This gives Ruby the chance to GC lines
+        # we are not interested in.
+        #
+        # We need to do a little extra work because we are not looking for just
+        # the lines that matches the query, but also for the context
+        # (surrounding lines). We will use Enumerable#each_cons to efficiently
+        # loop through the lines while keeping surrounding lines on hand.
+        #
+        # First, we turn "foo\nbar\nbaz" into
+        # [
+        #  [nil, -3], [nil, -2], [nil, -1],
+        #  ['foo', 0], ['bar', 1], ['baz', 3],
+        #  [nil, 4], [nil, 5], [nil, 6]
+        # ]
+        lines_with_index = Enumerator.new do |yielder|
+          # Yield fake 'before' lines for the first line of file_contents
+          (-SEARCH_CONTEXT_LINES..-1).each do |i|
+            yielder.yield [nil, i]
+          end
+
+          # Yield the actual file contents
+          count = 0
+          file_contents.each_line do |line|
+            line.chomp!
+            yielder.yield [line, count]
+            count += 1
+          end
+
+          # Yield fake 'after' lines for the last line of file_contents
+          (count + 1..count + SEARCH_CONTEXT_LINES).each do |i|
+            yielder.yield [nil, i]
+          end
+        end
+
+        greps = []
+
+        # Loop through consecutive blocks of lines with indexes
+        lines_with_index.each_cons(2 * SEARCH_CONTEXT_LINES + 1) do |line_block|
+          # Get the 'middle' line and index from the block
+          line, _i = line_block[SEARCH_CONTEXT_LINES]
+
+          next unless line && line.match(/#{Regexp.escape(query)}/i)
+
+          # Yay, 'line' contains a match!
+          # Get an array with just the context lines (no indexes)
+          match_with_context = line_block.map(&:first)
+          # Remove 'nil' lines in case we are close to the first or last line
+          match_with_context.compact!
+
+          # Get the line number (1-indexed) of the first context line
+          first_context_line_number = line_block[0][1] + 1
+
+          greps << Gitlab::Git::BlobSnippet.new(
+            ref,
+            match_with_context,
+            first_context_line_number,
+            filename
+          )
+        end
+
+        greps
+      end
+
+      # Return the Rugged patches for the diff between +from+ and +to+.
+      def diff_patches(from, to, options = {}, *paths)
+        options ||= {}
+        break_rewrites = options[:break_rewrites]
+        actual_options = Gitlab::Git::Diff.filter_diff_options(options.merge(paths: paths))
+
+        diff = rugged.diff(from, to, actual_options)
+        diff.find_similar!(break_rewrites: break_rewrites)
+        diff.each_patch
+      end
+    end
+  end
+end
diff --git a/lib/gitlab/git/tag.rb b/lib/gitlab/git/tag.rb
new file mode 100644
index 00000000000..bd3d1a6f283
--- /dev/null
+++ b/lib/gitlab/git/tag.rb
@@ -0,0 +1,17 @@
+module Gitlab
+  module Git
+    class Tag < Gitlab::Git::Ref
+      attr_reader :object_sha
+
+      def initialize(repository, name, target, message = nil)
+        super(repository, name, target)
+
+        @message = message
+      end
+
+      def message
+        encode! @message
+      end
+    end
+  end
+end
diff --git a/lib/gitlab/git/tree.rb b/lib/gitlab/git/tree.rb
new file mode 100644
index 00000000000..f7450e8b58f
--- /dev/null
+++ b/lib/gitlab/git/tree.rb
@@ -0,0 +1,104 @@
+module Gitlab
+  module Git
+    class Tree
+      include Gitlab::Git::EncodingHelper
+
+      attr_accessor :id, :root_id, :name, :path, :type,
+        :mode, :commit_id, :submodule_url
+
+      class << self
+        # Get list of tree objects
+        # for repository based on commit sha and path
+        # Uses rugged for raw objects
+        def where(repository, sha, path = nil)
+          path = nil if path == '' || path == '/'
+
+          commit = repository.lookup(sha)
+          root_tree = commit.tree
+
+          tree = if path
+                   id = find_id_by_path(repository, root_tree.oid, path)
+                   if id
+                     repository.lookup(id)
+                   else
+                     []
+                   end
+                 else
+                   root_tree
+                 end
+
+          tree.map do |entry|
+            new(
+              id: entry[:oid],
+              root_id: root_tree.oid,
+              name: entry[:name],
+              type: entry[:type],
+              mode: entry[:filemode],
+              path: path ? File.join(path, entry[:name]) : entry[:name],
+              commit_id: sha,
+            )
+          end
+        end
+
+        # Recursive search of tree id for path
+        #
+        # Ex.
+        #   blog/            # oid: 1a
+        #     app/           # oid: 2a
+        #       models/      # oid: 3a
+        #       views/       # oid: 4a
+        #
+        #
+        # Tree.find_id_by_path(repo, '1a', 'app/models') # => '3a'
+        #
+        def find_id_by_path(repository, root_id, path)
+          root_tree = repository.lookup(root_id)
+          path_arr = path.split('/')
+
+          entry = root_tree.find do |entry|
+            entry[:name] == path_arr[0] && entry[:type] == :tree
+          end
+
+          return nil unless entry
+
+          if path_arr.size > 1
+            path_arr.shift
+            find_id_by_path(repository, entry[:oid], path_arr.join('/'))
+          else
+            entry[:oid]
+          end
+        end
+      end
+
+      def initialize(options)
+        %w(id root_id name path type mode commit_id).each do |key|
+          self.send("#{key}=", options[key.to_sym])
+        end
+      end
+
+      def name
+        encode! @name
+      end
+
+      def dir?
+        type == :tree
+      end
+
+      def file?
+        type == :blob
+      end
+
+      def submodule?
+        type == :commit
+      end
+
+      def readme?
+        name =~ /^readme/i
+      end
+
+      def contributing?
+        name =~ /^contributing/i
+      end
+    end
+  end
+end
diff --git a/lib/gitlab/git/util.rb b/lib/gitlab/git/util.rb
new file mode 100644
index 00000000000..7973da2e8f8
--- /dev/null
+++ b/lib/gitlab/git/util.rb
@@ -0,0 +1,18 @@
+module Gitlab
+  module Git
+    module Util
+      LINE_SEP = "\n".freeze
+
+      def self.count_lines(string)
+        case string[-1]
+        when nil
+          0
+        when LINE_SEP
+          string.count(LINE_SEP)
+        else
+          string.count(LINE_SEP) + 1
+        end
+      end
+    end
+  end
+end
diff --git a/spec/gitlab_git_spec_helper.rb b/spec/gitlab_git_spec_helper.rb
new file mode 100644
index 00000000000..d0b1111b3e4
--- /dev/null
+++ b/spec/gitlab_git_spec_helper.rb
@@ -0,0 +1,30 @@
+require "spec_helper"
+
+require 'simplecov'
+SimpleCov.start
+
+require 'pry'
+require 'rspec/its'
+
+RSpec::Matchers.define :be_valid_commit do
+  match do |actual|
+    actual &&
+      actual.id == SeedRepo::Commit::ID &&
+      actual.message == SeedRepo::Commit::MESSAGE &&
+      actual.author_name == SeedRepo::Commit::AUTHOR_FULL_NAME
+  end
+end
+
+GITLAB_GIT_REPOS_PATH = Rails.root.join('tmp', 'gitlab_git_tests').to_s
+TEST_REPO_PATH = File.join(GITLAB_GIT_REPOS_PATH, 'gitlab-git-test.git')
+TEST_NORMAL_REPO_PATH = File.join(GITLAB_GIT_REPOS_PATH, "not-bare-repo.git")
+TEST_MUTABLE_REPO_PATH = File.join(GITLAB_GIT_REPOS_PATH, "mutable-repo.git")
+TEST_BROKEN_REPO_PATH = File.join(GITLAB_GIT_REPOS_PATH, "broken-repo.git")
+
+RSpec.configure do |config|
+  config.run_all_when_everything_filtered = true
+  config.filter_run :focus
+  config.order = 'random'
+  config.include SeedHelper
+  config.before(:all) { ensure_seeds }
+end
diff --git a/spec/lib/gitlab/git/attributes_spec.rb b/spec/lib/gitlab/git/attributes_spec.rb
new file mode 100644
index 00000000000..c970e73818b
--- /dev/null
+++ b/spec/lib/gitlab/git/attributes_spec.rb
@@ -0,0 +1,150 @@
+require "gitlab_git_spec_helper"
+
+describe Gitlab::Git::Attributes do
+  let(:path) do
+    File.expand_path(File.join(GITLAB_GIT_REPOS_PATH, 'with-git-attributes.git'))
+  end
+
+  subject { described_class.new(path) }
+
+  describe '#attributes' do
+    context 'using a path with attributes' do
+      it 'returns the attributes as a Hash' do
+        expect(subject.attributes('test.txt')).to eq({ 'text' => true })
+      end
+
+      it 'returns a Hash containing multiple attributes' do
+        expect(subject.attributes('test.sh')).
+          to eq({ 'eol' => 'lf', 'gitlab-language' => 'shell' })
+      end
+
+      it 'returns a Hash containing attributes for a file with multiple extensions' do
+        expect(subject.attributes('test.haml.html')).
+          to eq({ 'gitlab-language' => 'haml' })
+      end
+
+      it 'returns a Hash containing attributes for a file in a directory' do
+        expect(subject.attributes('foo/bar.txt')).to eq({ 'foo' => true })
+      end
+
+      it 'returns a Hash containing attributes with query string parameters' do
+        expect(subject.attributes('foo.cgi')).
+          to eq({ 'key' => 'value?p1=v1&p2=v2' })
+      end
+
+      it 'returns a Hash containing the attributes for an absolute path' do
+        expect(subject.attributes('/test.txt')).to eq({ 'text' => true })
+      end
+
+      it 'returns a Hash containing the attributes when a pattern is defined using an absolute path' do
+        # When a path is given without a leading slash it should still match
+        # patterns defined with a leading slash.
+        expect(subject.attributes('foo.png')).
+          to eq({ 'gitlab-language' => 'png' })
+
+        expect(subject.attributes('/foo.png')).
+          to eq({ 'gitlab-language' => 'png' })
+      end
+
+      it 'returns an empty Hash for a defined path without attributes' do
+        expect(subject.attributes('bla/bla.txt')).to eq({})
+      end
+
+      context 'when the "binary" option is set for a path' do
+        it 'returns true for the "binary" option' do
+          expect(subject.attributes('test.binary')['binary']).to eq(true)
+        end
+
+        it 'returns false for the "diff" option' do
+          expect(subject.attributes('test.binary')['diff']).to eq(false)
+        end
+      end
+    end
+
+    context 'using a path without any attributes' do
+      it 'returns an empty Hash' do
+        expect(subject.attributes('test.foo')).to eq({})
+      end
+    end
+  end
+
+  describe '#patterns' do
+    it 'parses a file with entries' do
+      expect(subject.patterns).to be_an_instance_of(Hash)
+    end
+
+    it 'parses an entry that uses a tab to separate the pattern and attributes' do
+      expect(subject.patterns[File.join(path, '*.md')]).
+        to eq({ 'gitlab-language' => 'markdown' })
+    end
+
+    it 'stores patterns in reverse order' do
+      first = subject.patterns.to_a[0]
+
+      expect(first[0]).to eq(File.join(path, 'bla/bla.txt'))
+    end
+
+    # It's a bit hard to test for something _not_ being processed. As such we'll
+    # just test the number of entries.
+    it 'ignores any comments and empty lines' do
+      expect(subject.patterns.length).to eq(10)
+    end
+
+    it 'does not parse anything when the attributes file does not exist' do
+      expect(File).to receive(:exist?).
+        with(File.join(path, 'info/attributes')).
+        and_return(false)
+
+      expect(subject.patterns).to eq({})
+    end
+  end
+
+  describe '#parse_attributes' do
+    it 'parses a boolean attribute' do
+      expect(subject.parse_attributes('text')).to eq({ 'text' => true })
+    end
+
+    it 'parses a negated boolean attribute' do
+      expect(subject.parse_attributes('-text')).to eq({ 'text' => false })
+    end
+
+    it 'parses a key-value pair' do
+      expect(subject.parse_attributes('foo=bar')).to eq({ 'foo' => 'bar' })
+    end
+
+    it 'parses multiple attributes' do
+      input = 'boolean key=value -negated'
+
+      expect(subject.parse_attributes(input)).
+        to eq({ 'boolean' => true, 'key' => 'value', 'negated' => false })
+    end
+
+    it 'parses attributes with query string parameters' do
+      expect(subject.parse_attributes('foo=bar?baz=1')).
+        to eq({ 'foo' => 'bar?baz=1' })
+    end
+  end
+
+  describe '#each_line' do
+    it 'iterates over every line in the attributes file' do
+      args = [String] * 14 # the number of lines in the file
+
+      expect { |b| subject.each_line(&b) }.to yield_successive_args(*args)
+    end
+
+    it 'does not yield when the attributes file does not exist' do
+      expect(File).to receive(:exist?).
+        with(File.join(path, 'info/attributes')).
+        and_return(false)
+
+      expect { |b| subject.each_line(&b) }.not_to yield_control
+    end
+
+    it 'does not yield when the attributes file has an unsupported encoding' do
+      path = File.expand_path(File.join(GITLAB_GIT_REPOS_PATH, 'with-invalid-git-attributes.git'))
+      attrs = described_class.new(path)
+
+      expect { |b| attrs.each_line(&b) }.not_to yield_control
+    end
+  end
+end
diff --git a/spec/lib/gitlab/git/blame_spec.rb b/spec/lib/gitlab/git/blame_spec.rb
new file mode 100644
index 00000000000..210dac626d4
--- /dev/null
+++ b/spec/lib/gitlab/git/blame_spec.rb
@@ -0,0 +1,66 @@
+# coding: utf-8
+require "gitlab_git_spec_helper"
+
+describe Gitlab::Git::Blame do
+  let(:repository) { Gitlab::Git::Repository.new(TEST_REPO_PATH) }
+  let(:blame) do
+    Gitlab::Git::Blame.new(repository, SeedRepo::Commit::ID, "CONTRIBUTING.md")
+  end
+
+  context "each count" do
+    it do
+      data = []
+      blame.each do |commit, line|
+        data << {
+          commit: commit,
+          line: line
+        }
+      end
+
+      expect(data.size).to eq(95)
+      expect(data.first[:commit]).to be_kind_of(Gitlab::Git::Commit)
+      expect(data.first[:line]).to eq("# Contribute to GitLab")
+    end
+  end
+
+  context "ISO-8859 encoding" do
+    let(:blame) do
+      Gitlab::Git::Blame.new(repository, SeedRepo::EncodingCommit::ID, "encoding/iso8859.txt")
+    end
+
+    it 'converts to UTF-8' do
+      data = []
+      blame.each do |commit, line|
+        data << {
+          commit: commit,
+          line: line
+        }
+      end
+
+      expect(data.size).to eq(1)
+      expect(data.first[:commit]).to be_kind_of(Gitlab::Git::Commit)
+      expect(data.first[:line]).to eq("Ä ü")
+    end
+  end
+
+  context "unknown encoding" do
+    let(:blame) do
+      Gitlab::Git::Blame.new(repository, SeedRepo::EncodingCommit::ID, "encoding/iso8859.txt")
+    end
+
+    it 'converts to UTF-8' do
+      expect(CharlockHolmes::EncodingDetector).to receive(:detect).and_return(nil)
+      data = []
+      blame.each do |commit, line|
+        data << {
+            commit: commit,
+            line: line
+        }
+      end
+
+      expect(data.size).to eq(1)
+      expect(data.first[:commit]).to be_kind_of(Gitlab::Git::Commit)
+      expect(data.first[:line]).to eq(" ")
+    end
+  end
+end
diff --git a/spec/lib/gitlab/git/blob_snippet_spec.rb b/spec/lib/gitlab/git/blob_snippet_spec.rb
new file mode 100644
index 00000000000..96679ae26d9
--- /dev/null
+++ b/spec/lib/gitlab/git/blob_snippet_spec.rb
@@ -0,0 +1,19 @@
+# encoding: UTF-8
+
+require "gitlab_git_spec_helper"
+
+describe Gitlab::Git::BlobSnippet do
+  describe :data do
+    context 'empty lines' do
+      let(:snippet) { Gitlab::Git::BlobSnippet.new('master', nil, nil, nil) }
+
+      it { expect(snippet.data).to be_nil }
+    end
+
+    context 'present lines' do
+      let(:snippet) { Gitlab::Git::BlobSnippet.new('master', ['wow', 'much'], 1, 'wow.rb') }
+
+      it { expect(snippet.data).to eq("wow\nmuch") }
+    end
+  end
+end
diff --git a/spec/lib/gitlab/git/blob_spec.rb b/spec/lib/gitlab/git/blob_spec.rb
new file mode 100644
index 00000000000..bd560bbf4e9
--- /dev/null
+++ b/spec/lib/gitlab/git/blob_spec.rb
@@ -0,0 +1,489 @@
+# encoding: utf-8
+
+require "gitlab_git_spec_helper"
+
+describe Gitlab::Git::Blob do
+  let(:repository) { Gitlab::Git::Repository.new(TEST_REPO_PATH) }
+
+  describe :initialize do
+    let(:blob) { Gitlab::Git::Blob.new(name: 'test') }
+
+    it 'handles nil data' do
+      expect(blob.name).to eq('test')
+      expect(blob.size).to eq(nil)
+      expect(blob.loaded_size).to eq(nil)
+    end
+  end
+
+  describe :find do
+    context 'file in subdir' do
+      let(:blob) { Gitlab::Git::Blob.find(repository, SeedRepo::Commit::ID, "files/ruby/popen.rb") }
+
+      it { expect(blob.id).to eq(SeedRepo::RubyBlob::ID) }
+      it { expect(blob.name).to eq(SeedRepo::RubyBlob::NAME) }
+      it { expect(blob.path).to eq("files/ruby/popen.rb") }
+      it { expect(blob.commit_id).to eq(SeedRepo::Commit::ID) }
+      it { expect(blob.data[0..10]).to eq(SeedRepo::RubyBlob::CONTENT[0..10]) }
+      it { expect(blob.size).to eq(669) }
+      it { expect(blob.mode).to eq("100644") }
+    end
+
+    context 'file in root' do
+      let(:blob) { Gitlab::Git::Blob.find(repository, SeedRepo::Commit::ID, ".gitignore") }
+
+      it { expect(blob.id).to eq("dfaa3f97ca337e20154a98ac9d0be76ddd1fcc82") }
+      it { expect(blob.name).to eq(".gitignore") }
+      it { expect(blob.path).to eq(".gitignore") }
+      it { expect(blob.commit_id).to eq(SeedRepo::Commit::ID) }
+      it { expect(blob.data[0..10]).to eq("*.rbc\n*.sas") }
+      it { expect(blob.size).to eq(241) }
+      it { expect(blob.mode).to eq("100644") }
+      it { expect(blob).not_to be_binary }
+    end
+
+    context 'file in root with leading slash' do
+      let(:blob) { Gitlab::Git::Blob.find(repository, SeedRepo::Commit::ID, "/.gitignore") }
+
+      it { expect(blob.id).to eq("dfaa3f97ca337e20154a98ac9d0be76ddd1fcc82") }
+      it { expect(blob.name).to eq(".gitignore") }
+      it { expect(blob.path).to eq(".gitignore") }
+      it { expect(blob.commit_id).to eq(SeedRepo::Commit::ID) }
+      it { expect(blob.data[0..10]).to eq("*.rbc\n*.sas") }
+      it { expect(blob.size).to eq(241) }
+      it { expect(blob.mode).to eq("100644") }
+    end
+
+    context 'non-exist file' do
+      let(:blob) { Gitlab::Git::Blob.find(repository, SeedRepo::Commit::ID, "missing.rb") }
+
+      it { expect(blob).to be_nil }
+    end
+
+    context 'six submodule' do
+      let(:blob) { Gitlab::Git::Blob.find(repository, SeedRepo::Commit::ID, 'six') }
+
+      it { expect(blob.id).to eq('409f37c4f05865e4fb208c771485f211a22c4c2d') }
+      it { expect(blob.data).to eq('') }
+
+      it 'does not get messed up by load_all_data!' do
+        blob.load_all_data!(repository)
+        expect(blob.data).to eq('')
+      end
+
+      it 'does not mark the blob as binary' do
+        expect(blob).not_to be_binary
+      end
+    end
+
+    context 'large file' do
+      let(:blob) { Gitlab::Git::Blob.find(repository, SeedRepo::Commit::ID, 'files/images/6049019_460s.jpg') }
+      let(:blob_size) { 111803 }
+
+      it { expect(blob.size).to eq(blob_size) }
+      it { expect(blob.data.length).to eq(blob_size) }
+
+      it 'check that this test is sane' do
+        expect(blob.size).to be <= Gitlab::Git::Blob::MAX_DATA_DISPLAY_SIZE
+      end
+
+      it 'can load all data' do
+        blob.load_all_data!(repository)
+        expect(blob.data.length).to eq(blob_size)
+      end
+
+      it 'marks the blob as binary' do
+        expect(Gitlab::Git::Blob).to receive(:new).
+          with(hash_including(binary: true)).
+          and_call_original
+
+        expect(blob).to be_binary
+      end
+    end
+  end
+
+  describe :raw do
+    let(:raw_blob) { Gitlab::Git::Blob.raw(repository, SeedRepo::RubyBlob::ID) }
+    it { expect(raw_blob.id).to eq(SeedRepo::RubyBlob::ID) }
+    it { expect(raw_blob.data[0..10]).to eq("require \'fi") }
+    it { expect(raw_blob.size).to eq(669) }
+    it { expect(raw_blob.truncated?).to be_falsey }
+
+    context 'large file' do
+      it 'limits the size of a large file' do
+        blob_size = Gitlab::Git::Blob::MAX_DATA_DISPLAY_SIZE + 1
+        buffer = Array.new(blob_size, 0)
+        rugged_blob = Rugged::Blob.from_buffer(repository.rugged, buffer.join(''))
+        blob = Gitlab::Git::Blob.raw(repository, rugged_blob)
+
+        expect(blob.size).to eq(blob_size)
+        expect(blob.loaded_size).to eq(Gitlab::Git::Blob::MAX_DATA_DISPLAY_SIZE)
+        expect(blob.data.length).to eq(Gitlab::Git::Blob::MAX_DATA_DISPLAY_SIZE)
+        expect(blob.truncated?).to be_truthy
+
+        blob.load_all_data!(repository)
+        expect(blob.loaded_size).to eq(blob_size)
+      end
+    end
+  end
+
+  describe 'encoding' do
+    context 'file with russian text' do
+      let(:blob) { Gitlab::Git::Blob.find(repository, SeedRepo::Commit::ID, "encoding/russian.rb") }
+
+      it { expect(blob.name).to eq("russian.rb") }
+      it { expect(blob.data.lines.first).to eq("Хороший файл") }
+      it { expect(blob.size).to eq(23) }
+      it { expect(blob.truncated?).to be_falsey }
+      # Run it twice since data is encoded after the first run
+      it { expect(blob.truncated?).to be_falsey }
+      it { expect(blob.mode).to eq("100755") }
+    end
+
+    context 'file with Chinese text' do
+      let(:blob) { Gitlab::Git::Blob.find(repository, SeedRepo::Commit::ID, "encoding/テスト.txt") }
+
+      it { expect(blob.name).to eq("テスト.txt") }
+      it { expect(blob.data).to include("これはテスト") }
+      it { expect(blob.size).to eq(340) }
+      it { expect(blob.mode).to eq("100755") }
+      it { expect(blob.truncated?).to be_falsey }
+    end
+
+    context 'file with ISO-8859 text' do
+      let(:blob) { Gitlab::Git::Blob.find(repository, SeedRepo::LastCommit::ID, "encoding/iso8859.txt") }
+
+      it { expect(blob.name).to eq("iso8859.txt") }
+      it { expect(blob.loaded_size).to eq(4) }
+      it { expect(blob.size).to eq(4) }
+      it { expect(blob.mode).to eq("100644") }
+      it { expect(blob.truncated?).to be_falsey }
+    end
+  end
+
+  describe 'mode' do
+    context 'file regular' do
+      let(:blob) do
+        Gitlab::Git::Blob.find(
+          repository,
+          'fa1b1e6c004a68b7d8763b86455da9e6b23e36d6',
+          'files/ruby/regex.rb'
+        )
+      end
+
+      it { expect(blob.name).to eq('regex.rb') }
+      it { expect(blob.path).to eq('files/ruby/regex.rb') }
+      it { expect(blob.size).to eq(1200) }
+      it { expect(blob.mode).to eq("100644") }
+    end
+
+    context 'file binary' do
+      let(:blob) do
+        Gitlab::Git::Blob.find(
+          repository,
+          'fa1b1e6c004a68b7d8763b86455da9e6b23e36d6',
+          'files/executables/ls'
+        )
+      end
+
+      it { expect(blob.name).to eq('ls') }
+      it { expect(blob.path).to eq('files/executables/ls') }
+      it { expect(blob.size).to eq(110080) }
+      it { expect(blob.mode).to eq("100755") }
+    end
+
+    context 'file symlink to regular' do
+      let(:blob) do
+        Gitlab::Git::Blob.find(
+          repository,
+          'fa1b1e6c004a68b7d8763b86455da9e6b23e36d6',
+          'files/links/ruby-style-guide.md'
+        )
+      end
+
+      it { expect(blob.name).to eq('ruby-style-guide.md') }
+      it { expect(blob.path).to eq('files/links/ruby-style-guide.md') }
+      it { expect(blob.size).to eq(31) }
+      it { expect(blob.mode).to eq("120000") }
+    end
+
+    context 'file symlink to binary' do
+      let(:blob) do
+        Gitlab::Git::Blob.find(
+          repository,
+          'fa1b1e6c004a68b7d8763b86455da9e6b23e36d6',
+          'files/links/touch'
+        )
+      end
+
+      it { expect(blob.name).to eq('touch') }
+      it { expect(blob.path).to eq('files/links/touch') }
+      it { expect(blob.size).to eq(20) }
+      it { expect(blob.mode).to eq("120000") }
+    end
+  end
+
+  describe :commit do
+    let(:repository) { Gitlab::Git::Repository.new(TEST_REPO_PATH) }
+
+    let(:commit_options) do
+      {
+         file: {
+           content: 'Lorem ipsum...',
+           path: 'documents/story.txt'
+         },
+         author: {
+           email: 'user@example.com',
+           name: 'Test User',
+           time: Time.now
+         },
+         committer: {
+           email: 'user@example.com',
+           name: 'Test User',
+           time: Time.now
+         },
+         commit: {
+           message: 'Wow such commit',
+           branch: 'fix-mode'
+         }
+      }
+    end
+
+    let(:commit_sha) { Gitlab::Git::Blob.commit(repository, commit_options) }
+    let(:commit) { repository.lookup(commit_sha) }
+
+    it 'should add file with commit' do
+      # Commit message valid
+      expect(commit.message).to eq('Wow such commit')
+
+      tree = commit.tree.to_a.find { |tree| tree[:name] == 'documents' }
+
+      # Directory was created
+      expect(tree[:type]).to eq(:tree)
+
+      # File was created
+      expect(repository.lookup(tree[:oid]).first[:name]).to eq('story.txt')
+    end
+
+    describe "ref updating" do
+      it 'creates a commit but does not udate a ref' do
+        commit_opts = commit_options.tap{ |opts| opts[:commit][:update_ref] = false}
+        commit_sha = Gitlab::Git::Blob.commit(repository, commit_opts)
+        commit = repository.lookup(commit_sha)
+
+        # Commit message valid
+        expect(commit.message).to eq('Wow such commit')
+
+        # Does not update any related ref
+        expect(repository.lookup("fix-mode").oid).not_to eq(commit.oid)
+        expect(repository.lookup("HEAD").oid).not_to eq(commit.oid)
+      end
+    end
+
+    describe 'reject updates' do
+      it 'should reject updates' do
+        commit_options[:file][:update] = false
+        commit_options[:file][:path] = 'files/executables/ls'
+
+        expect{ commit_sha }.to raise_error('Filename already exists; update not allowed')
+      end
+    end
+
+    describe 'file modes' do
+      it 'should preserve file modes with commit' do
+        commit_options[:file][:path] = 'files/executables/ls'
+
+        entry = Gitlab::Git::Blob::find_entry_by_path(repository, commit.tree.oid, commit_options[:file][:path])
+        expect(entry[:filemode]).to eq(0100755)
+      end
+    end
+  end
+
+  describe :rename do
+    let(:repository) { Gitlab::Git::Repository.new(TEST_NORMAL_REPO_PATH) }
+    let(:rename_options) do
+      {
+        file: {
+          path: 'NEWCONTRIBUTING.md',
+          previous_path: 'CONTRIBUTING.md',
+          content: 'Lorem ipsum...',
+          update: true
+        },
+        author: {
+          email: 'user@example.com',
+          name: 'Test User',
+          time: Time.now
+        },
+        committer: {
+          email: 'user@example.com',
+          name: 'Test User',
+          time: Time.now
+        },
+        commit: {
+          message: 'Rename readme',
+          branch: 'master'
+        }
+      }
+    end
+
+    let(:rename_options2) do
+      {
+         file: {
+           content: 'Lorem ipsum...',
+           path: 'bin/new_executable',
+           previous_path: 'bin/executable',
+         },
+         author: {
+           email: 'user@example.com',
+           name: 'Test User',
+           time: Time.now
+         },
+         committer: {
+           email: 'user@example.com',
+           name: 'Test User',
+           time: Time.now
+         },
+         commit: {
+           message: 'Updates toberenamed.txt',
+           branch: 'master',
+           update_ref: false
+         }
+      }
+    end
+
+    it 'maintains file permissions when renaming' do
+      mode = 0o100755
+
+      Gitlab::Git::Blob.rename(repository, rename_options2)
+
+      expect(repository.rugged.index.get(rename_options2[:file][:path])[:mode]).to eq(mode)
+    end
+
+    it 'renames the file with commit and not change file permissions' do
+      ref = rename_options[:commit][:branch]
+
+      expect(repository.rugged.index.get('CONTRIBUTING.md')).not_to be_nil
+      expect { Gitlab::Git::Blob.rename(repository, rename_options) }.to change { repository.commit_count(ref) }.by(1)
+
+      expect(repository.rugged.index.get('CONTRIBUTING.md')).to be_nil
+      expect(repository.rugged.index.get('NEWCONTRIBUTING.md')).not_to be_nil
+    end
+  end
+
+  describe :remove do
+    let(:repository) { Gitlab::Git::Repository.new(TEST_REPO_PATH) }
+
+    let(:commit_options) do
+      {
+         file: {
+           path: 'README.md'
+         },
+         author: {
+           email: 'user@example.com',
+           name: 'Test User',
+           time: Time.now
+         },
+         committer: {
+           email: 'user@example.com',
+           name: 'Test User',
+           time: Time.now
+         },
+         commit: {
+           message: 'Remove readme',
+           branch: 'feature'
+         }
+      }
+    end
+
+    let(:commit_sha) { Gitlab::Git::Blob.remove(repository, commit_options) }
+    let(:commit) { repository.lookup(commit_sha) }
+    let(:blob) { Gitlab::Git::Blob.find(repository, commit_sha, "README.md") }
+
+    it 'should remove file with commit' do
+      # Commit message valid
+      expect(commit.message).to eq('Remove readme')
+
+      # File was removed
+      expect(blob).to be_nil
+    end
+  end
+
+  describe :lfs_pointers do
+    context 'file a valid lfs pointer' do
+      let(:blob) do
+        Gitlab::Git::Blob.find(
+          repository,
+          '33bcff41c232a11727ac6d660bd4b0c2ba86d63d',
+          'files/lfs/image.jpg'
+        )
+      end
+
+      it { expect(blob.lfs_pointer?).to eq(true) }
+      it { expect(blob.lfs_oid).to eq("4206f951d2691c78aac4c0ce9f2b23580b2c92cdcc4336e1028742c0274938e0") }
+      it { expect(blob.lfs_size).to eq("19548") }
+      it { expect(blob.id).to eq("f4d76af13003d1106be7ac8c5a2a3d37ddf32c2a") }
+      it { expect(blob.name).to eq("image.jpg") }
+      it { expect(blob.path).to eq("files/lfs/image.jpg") }
+      it { expect(blob.size).to eq(130) }
+      it { expect(blob.mode).to eq("100644") }
+    end
+
+    describe 'file an invalid lfs pointer' do
+      context 'with correct version header but incorrect size and oid' do
+        let(:blob) do
+          Gitlab::Git::Blob.find(
+            repository,
+            '33bcff41c232a11727ac6d660bd4b0c2ba86d63d',
+            'files/lfs/archive-invalid.tar'
+          )
+        end
+
+        it { expect(blob.lfs_pointer?).to eq(false) }
+        it { expect(blob.lfs_oid).to eq(nil) }
+        it { expect(blob.lfs_size).to eq(nil) }
+        it { expect(blob.id).to eq("f8a898db217a5a85ed8b3d25b34c1df1d1094c46") }
+        it { expect(blob.name).to eq("archive-invalid.tar") }
+        it { expect(blob.path).to eq("files/lfs/archive-invalid.tar") }
+        it { expect(blob.size).to eq(43) }
+        it { expect(blob.mode).to eq("100644") }
+      end
+
+      context 'with correct version header and size but incorrect size and oid' do
+        let(:blob) do
+          Gitlab::Git::Blob.find(
+            repository,
+            '33bcff41c232a11727ac6d660bd4b0c2ba86d63d',
+            'files/lfs/picture-invalid.png'
+          )
+        end
+
+        it { expect(blob.lfs_pointer?).to eq(false) }
+        it { expect(blob.lfs_oid).to eq(nil) }
+        it { expect(blob.lfs_size).to eq("1575078") }
+        it { expect(blob.id).to eq("5ae35296e1f95c1ef9feda1241477ed29a448572") }
+        it { expect(blob.name).to eq("picture-invalid.png") }
+        it { expect(blob.path).to eq("files/lfs/picture-invalid.png") }
+        it { expect(blob.size).to eq(57) }
+        it { expect(blob.mode).to eq("100644") }
+      end
+
+      context 'with correct version header and size but invalid size and oid' do
+        let(:blob) do
+          Gitlab::Git::Blob.find(
+            repository,
+            '33bcff41c232a11727ac6d660bd4b0c2ba86d63d',
+            'files/lfs/file-invalid.zip'
+          )
+        end
+
+        it { expect(blob.lfs_pointer?).to eq(false) }
+        it { expect(blob.lfs_oid).to eq(nil) }
+        it { expect(blob.lfs_size).to eq(nil) }
+        it { expect(blob.id).to eq("d831981bd876732b85a1bcc6cc01210c9f36248f") }
+        it { expect(blob.name).to eq("file-invalid.zip") }
+        it { expect(blob.path).to eq("files/lfs/file-invalid.zip") }
+        it { expect(blob.size).to eq(60) }
+        it { expect(blob.mode).to eq("100644") }
+      end
+    end
+  end
+end
diff --git a/spec/lib/gitlab/git/branch_spec.rb b/spec/lib/gitlab/git/branch_spec.rb
new file mode 100644
index 00000000000..8a17d8cf12f
--- /dev/null
+++ b/spec/lib/gitlab/git/branch_spec.rb
@@ -0,0 +1,31 @@
+require "gitlab_git_spec_helper"
+
+describe Gitlab::Git::Branch do
+  let(:repository) { Gitlab::Git::Repository.new(TEST_REPO_PATH) }
+
+  subject { repository.branches }
+
+  it { is_expected.to be_kind_of Array }
+
+  describe '#size' do
+    subject { super().size }
+    it { is_expected.to eq(SeedRepo::Repo::BRANCHES.size) }
+  end
+
+  describe 'first branch' do
+    let(:branch) { repository.branches.first }
+
+    it { expect(branch.name).to eq(SeedRepo::Repo::BRANCHES.first) }
+    it { expect(branch.dereferenced_target.sha).to eq("0b4bc9a49b562e85de7cc9e834518ea6828729b9") }
+  end
+
+  describe 'master branch' do
+    let(:branch) do
+      repository.branches.find { |branch| branch.name == 'master' }
+    end
+
+    it { expect(branch.dereferenced_target.sha).to eq(SeedRepo::LastCommit::ID) }
+  end
+
+  it { expect(repository.branches.size).to eq(SeedRepo::Repo::BRANCHES.size) }
+end
diff --git a/spec/lib/gitlab/git/commit_spec.rb b/spec/lib/gitlab/git/commit_spec.rb
new file mode 100644
index 00000000000..9dabf00a357
--- /dev/null
+++ b/spec/lib/gitlab/git/commit_spec.rb
@@ -0,0 +1,408 @@
+require "gitlab_git_spec_helper"
+
+describe Gitlab::Git::Commit do
+  let(:repository) { Gitlab::Git::Repository.new(TEST_REPO_PATH) }
+  let(:commit) { Gitlab::Git::Commit.find(repository, SeedRepo::Commit::ID) }
+  let(:rugged_commit) do
+    repository.rugged.lookup(SeedRepo::Commit::ID)
+  end
+
+  describe "Commit info" do
+    before do
+      repo = Gitlab::Git::Repository.new(TEST_REPO_PATH).rugged
+
+      @committer = {
+        email: 'mike@smith.com',
+        name: "Mike Smith",
+        time: Time.now
+      }
+
+      @author = {
+        email: 'john@smith.com',
+        name: "John Smith",
+        time: Time.now
+      }
+
+      @parents = [repo.head.target]
+      @gitlab_parents = @parents.map { |c| Gitlab::Git::Commit.decorate(c) }
+      @tree = @parents.first.tree
+
+      sha = Rugged::Commit.create(
+        repo,
+        author: @author,
+        committer: @committer,
+        tree: @tree,
+        parents: @parents,
+        message: "Refactoring specs",
+        update_ref: "HEAD"
+      )
+
+      @raw_commit = repo.lookup(sha)
+      @commit = Gitlab::Git::Commit.new(@raw_commit)
+    end
+
+    it { expect(@commit.short_id).to eq(@raw_commit.oid[0..10]) }
+    it { expect(@commit.id).to eq(@raw_commit.oid) }
+    it { expect(@commit.sha).to eq(@raw_commit.oid) }
+    it { expect(@commit.safe_message).to eq(@raw_commit.message) }
+    it { expect(@commit.created_at).to eq(@raw_commit.author[:time]) }
+    it { expect(@commit.date).to eq(@raw_commit.committer[:time]) }
+    it { expect(@commit.author_email).to eq(@author[:email]) }
+    it { expect(@commit.author_name).to eq(@author[:name]) }
+    it { expect(@commit.committer_name).to eq(@committer[:name]) }
+    it { expect(@commit.committer_email).to eq(@committer[:email]) }
+    it { expect(@commit.different_committer?).to be_truthy }
+    it { expect(@commit.parents).to eq(@gitlab_parents) }
+    it { expect(@commit.parent_id).to eq(@parents.first.oid) }
+    it { expect(@commit.no_commit_message).to eq("--no commit message") }
+    it { expect(@commit.tree).to eq(@tree) }
+
+    after do
+      # Erase the new commit so other tests get the original repo
+      repo = Gitlab::Git::Repository.new(TEST_REPO_PATH).rugged
+      repo.references.update("refs/heads/master", SeedRepo::LastCommit::ID)
+    end
+  end
+
+  context 'Class methods' do
+    describe :find do
+      it "should return first head commit if without params" do
+        expect(Gitlab::Git::Commit.last(repository).id).to eq(
+          repository.raw.head.target.oid
+        )
+      end
+
+      it "should return valid commit" do
+        expect(Gitlab::Git::Commit.find(repository, SeedRepo::Commit::ID)).to be_valid_commit
+      end
+
+      it "should return valid commit for tag" do
+        expect(Gitlab::Git::Commit.find(repository, 'v1.0.0').id).to eq('6f6d7e7ed97bb5f0054f2b1df789b39ca89b6ff9')
+      end
+
+      it "should return nil for non-commit ids" do
+        blob = Gitlab::Git::Blob.find(repository, SeedRepo::Commit::ID, "files/ruby/popen.rb")
+        expect(Gitlab::Git::Commit.find(repository, blob.id)).to be_nil
+      end
+
+      it "should return nil for parent of non-commit object" do
+        blob = Gitlab::Git::Blob.find(repository, SeedRepo::Commit::ID, "files/ruby/popen.rb")
+        expect(Gitlab::Git::Commit.find(repository, "#{blob.id}^")).to be_nil
+      end
+
+      it "should return nil for nonexisting ids" do
+        expect(Gitlab::Git::Commit.find(repository, "+123_4532530XYZ")).to be_nil
+      end
+
+      context 'with broken repo' do
+        let(:repository) { Gitlab::Git::Repository.new(TEST_BROKEN_REPO_PATH) }
+
+        it 'returns nil' do
+          expect(Gitlab::Git::Commit.find(repository, SeedRepo::Commit::ID)).to be_nil
+        end
+      end
+    end
+
+    describe :last_for_path do
+      context 'no path' do
+        subject { Gitlab::Git::Commit.last_for_path(repository, 'master') }
+
+        describe '#id' do
+          subject { super().id }
+          it { is_expected.to eq(SeedRepo::LastCommit::ID) }
+        end
+      end
+
+      context 'path' do
+        subject { Gitlab::Git::Commit.last_for_path(repository, 'master', 'files/ruby') }
+
+        describe '#id' do
+          subject { super().id }
+          it { is_expected.to eq(SeedRepo::Commit::ID) }
+        end
+      end
+
+      context 'ref + path' do
+        subject { Gitlab::Git::Commit.last_for_path(repository, SeedRepo::Commit::ID, 'encoding') }
+
+        describe '#id' do
+          subject { super().id }
+          it { is_expected.to eq(SeedRepo::BigCommit::ID) }
+        end
+      end
+    end
+
+    describe "where" do
+      context 'path is empty string' do
+        subject do
+          commits = Gitlab::Git::Commit.where(
+            repo: repository,
+            ref: 'master',
+            path: '',
+            limit: 10
+          )
+
+          commits.map { |c| c.id }
+        end
+
+        it 'has 10 elements' do
+          expect(subject.size).to eq(10)
+        end
+        it { is_expected.to include(SeedRepo::EmptyCommit::ID) }
+      end
+
+      context 'path is nil' do
+        subject do
+          commits = Gitlab::Git::Commit.where(
+            repo: repository,
+            ref: 'master',
+            path: nil,
+            limit: 10
+          )
+
+          commits.map { |c| c.id }
+        end
+
+        it 'has 10 elements' do
+          expect(subject.size).to eq(10)
+        end
+        it { is_expected.to include(SeedRepo::EmptyCommit::ID) }
+      end
+
+      context 'ref is branch name' do
+        subject do
+          commits = Gitlab::Git::Commit.where(
+            repo: repository,
+            ref: 'master',
+            path: 'files',
+            limit: 3,
+            offset: 1
+          )
+
+          commits.map { |c| c.id }
+        end
+
+        it 'has 3 elements' do
+          expect(subject.size).to eq(3)
+        end
+        it { is_expected.to include("d14d6c0abdd253381df51a723d58691b2ee1ab08") }
+        it { is_expected.not_to include("eb49186cfa5c4338011f5f590fac11bd66c5c631") }
+      end
+
+      context 'ref is commit id' do
+        subject do
+          commits = Gitlab::Git::Commit.where(
+            repo: repository,
+            ref: "874797c3a73b60d2187ed6e2fcabd289ff75171e",
+            path: 'files',
+            limit: 3,
+            offset: 1
+          )
+
+          commits.map { |c| c.id }
+        end
+
+        it 'has 3 elements' do
+          expect(subject.size).to eq(3)
+        end
+        it { is_expected.to include("2f63565e7aac07bcdadb654e253078b727143ec4") }
+        it { is_expected.not_to include(SeedRepo::Commit::ID) }
+      end
+
+      context 'ref is tag' do
+        subject do
+          commits = Gitlab::Git::Commit.where(
+            repo: repository,
+            ref: 'v1.0.0',
+            path: 'files',
+            limit: 3,
+            offset: 1
+          )
+
+          commits.map { |c| c.id }
+        end
+
+        it 'has 3 elements' do
+          expect(subject.size).to eq(3)
+        end
+        it { is_expected.to include("874797c3a73b60d2187ed6e2fcabd289ff75171e") }
+        it { is_expected.not_to include(SeedRepo::Commit::ID) }
+      end
+    end
+
+    describe :between do
+      subject do
+        commits = Gitlab::Git::Commit.between(repository, SeedRepo::Commit::PARENT_ID, SeedRepo::Commit::ID)
+        commits.map { |c| c.id }
+      end
+
+      it 'has 1 element' do
+        expect(subject.size).to eq(1)
+      end
+      it { is_expected.to include(SeedRepo::Commit::ID) }
+      it { is_expected.not_to include(SeedRepo::FirstCommit::ID) }
+    end
+
+    describe :find_all do
+      context 'max_count' do
+        subject do
+          commits = Gitlab::Git::Commit.find_all(
+            repository,
+            max_count: 50
+          )
+
+          commits.map { |c| c.id }
+        end
+
+        it 'has 31 elements' do
+          expect(subject.size).to eq(33)
+        end
+        it { is_expected.to include(SeedRepo::Commit::ID) }
+        it { is_expected.to include(SeedRepo::Commit::PARENT_ID) }
+        it { is_expected.to include(SeedRepo::FirstCommit::ID) }
+      end
+
+      context 'ref + max_count + skip' do
+        subject do
+          commits = Gitlab::Git::Commit.find_all(
+            repository,
+            ref: 'master',
+            max_count: 50,
+            skip: 1
+          )
+
+          commits.map { |c| c.id }
+        end
+
+        it 'has 23 elements' do
+          expect(subject.size).to eq(24)
+        end
+        it { is_expected.to include(SeedRepo::Commit::ID) }
+        it { is_expected.to include(SeedRepo::FirstCommit::ID) }
+        it { is_expected.not_to include(SeedRepo::LastCommit::ID) }
+      end
+
+      context 'contains feature + max_count' do
+        subject do
+          commits = Gitlab::Git::Commit.find_all(
+            repository,
+            contains: 'feature',
+            max_count: 7
+          )
+
+          commits.map { |c| c.id }
+        end
+
+        it 'has 7 elements' do
+          expect(subject.size).to eq(7)
+        end
+
+        it { is_expected.not_to include(SeedRepo::Commit::PARENT_ID) }
+        it { is_expected.not_to include(SeedRepo::Commit::ID) }
+        it { is_expected.to include(SeedRepo::BigCommit::ID) }
+      end
+    end
+  end
+
+  describe :init_from_rugged do
+    let(:gitlab_commit) { Gitlab::Git::Commit.new(rugged_commit) }
+    subject { gitlab_commit }
+
+    describe '#id' do
+      subject { super().id }
+      it { is_expected.to eq(SeedRepo::Commit::ID) }
+    end
+  end
+
+  describe :init_from_hash do
+    let(:commit) { Gitlab::Git::Commit.new(sample_commit_hash) }
+    subject { commit }
+
+    describe '#id' do
+      subject { super().id }
+      it { is_expected.to eq(sample_commit_hash[:id])}
+    end
+
+    describe '#message' do
+      subject { super().message }
+      it { is_expected.to eq(sample_commit_hash[:message])}
+    end
+  end
+
+  describe :stats do
+    subject { commit.stats }
+
+    describe '#additions' do
+      subject { super().additions }
+      it { is_expected.to eq(11) }
+    end
+
+    describe '#deletions' do
+      subject { super().deletions }
+      it { is_expected.to eq(6) }
+    end
+  end
+
+  describe :to_diff do
+    subject { commit.to_diff }
+
+    it { is_expected.not_to include "From #{SeedRepo::Commit::ID}" }
+    it { is_expected.to include 'diff --git a/files/ruby/popen.rb b/files/ruby/popen.rb'}
+  end
+
+  describe :has_zero_stats? do
+    it { expect(commit.has_zero_stats?).to eq(false) }
+  end
+
+  describe :to_patch do
+    subject { commit.to_patch }
+
+    it { is_expected.to include "From #{SeedRepo::Commit::ID}" }
+    it { is_expected.to include 'diff --git a/files/ruby/popen.rb b/files/ruby/popen.rb'}
+  end
+
+  describe :to_hash do
+    let(:hash) { commit.to_hash }
+    subject { hash }
+
+    it { is_expected.to be_kind_of Hash }
+
+    describe '#keys' do
+      subject { super().keys.sort }
+      it { is_expected.to match(sample_commit_hash.keys.sort) }
+    end
+  end
+
+  describe :diffs do
+    subject { commit.diffs }
+
+    it { is_expected.to be_kind_of Gitlab::Git::DiffCollection }
+    it { expect(subject.count).to eq(2) }
+    it { expect(subject.first).to be_kind_of Gitlab::Git::Diff }
+  end
+
+  describe :ref_names do
+    let(:commit) { Gitlab::Git::Commit.find(repository, 'master') }
+    subject { commit.ref_names(repository) }
+
+    it 'has 1 element' do
+      expect(subject.size).to eq(1)
+    end
+    it { is_expected.to include("master") }
+    it { is_expected.not_to include("feature") }
+  end
+
+  def sample_commit_hash
+    {
+      author_email: "dmitriy.zaporozhets@gmail.com",
+      author_name: "Dmitriy Zaporozhets",
+      authored_date: "2012-02-27 20:51:12 +0200",
+      committed_date: "2012-02-27 20:51:12 +0200",
+      committer_email: "dmitriy.zaporozhets@gmail.com",
+      committer_name: "Dmitriy Zaporozhets",
+      id: SeedRepo::Commit::ID,
+      message: "tree css fixes",
+      parent_ids: ["874797c3a73b60d2187ed6e2fcabd289ff75171e"]
+    }
+  end
+end
diff --git a/spec/lib/gitlab/git/compare_spec.rb b/spec/lib/gitlab/git/compare_spec.rb
new file mode 100644
index 00000000000..44c396a029b
--- /dev/null
+++ b/spec/lib/gitlab/git/compare_spec.rb
@@ -0,0 +1,109 @@
+require "gitlab_git_spec_helper"
+
+describe Gitlab::Git::Compare do
+  let(:repository) { Gitlab::Git::Repository.new(TEST_REPO_PATH) }
+  let(:compare) { Gitlab::Git::Compare.new(repository, SeedRepo::BigCommit::ID, SeedRepo::Commit::ID, false) }
+  let(:compare_straight) { Gitlab::Git::Compare.new(repository, SeedRepo::BigCommit::ID, SeedRepo::Commit::ID, true) }
+
+  describe :commits do
+    subject do
+      compare.commits.map(&:id)
+    end
+
+    it 'has 8 elements' do
+      expect(subject.size).to eq(8)
+    end
+
+    it { is_expected.to include(SeedRepo::Commit::PARENT_ID) }
+    it { is_expected.not_to include(SeedRepo::BigCommit::PARENT_ID) }
+
+    context 'non-existing base ref' do
+      let(:compare) { Gitlab::Git::Compare.new(repository, 'no-such-branch', SeedRepo::Commit::ID) }
+
+      it { is_expected.to be_empty }
+    end
+
+    context 'non-existing head ref' do
+      let(:compare) { Gitlab::Git::Compare.new(repository, SeedRepo::BigCommit::ID, '1234567890') }
+
+      it { is_expected.to be_empty }
+    end
+
+    context 'base ref is equal to head ref' do
+      let(:compare) { Gitlab::Git::Compare.new(repository, SeedRepo::BigCommit::ID, SeedRepo::BigCommit::ID) }
+
+      it { is_expected.to be_empty }
+    end
+
+    context 'providing nil as base ref or head ref' do
+      let(:compare) { Gitlab::Git::Compare.new(repository, nil, nil) }
+
+      it { is_expected.to be_empty }
+    end
+  end
+
+  describe :diffs do
+    subject do
+      compare.diffs.map(&:new_path)
+    end
+
+    it 'has 10 elements' do
+      expect(subject.size).to eq(10)
+    end
+
+    it { is_expected.to include('files/ruby/popen.rb') }
+    it { is_expected.not_to include('LICENSE') }
+
+    context 'non-existing base ref' do
+      let(:compare) { Gitlab::Git::Compare.new(repository, 'no-such-branch', SeedRepo::Commit::ID) }
+
+      it { is_expected.to be_empty }
+    end
+
+    context 'non-existing head ref' do
+      let(:compare) { Gitlab::Git::Compare.new(repository, SeedRepo::BigCommit::ID, '1234567890') }
+
+      it { is_expected.to be_empty }
+    end
+  end
+
+  describe :same  do
+    subject do
+      compare.same
+    end
+
+    it { is_expected.to eq(false) }
+
+    context 'base ref is equal to head ref' do
+      let(:compare) { Gitlab::Git::Compare.new(repository, SeedRepo::BigCommit::ID, SeedRepo::BigCommit::ID) }
+
+      it { is_expected.to eq(true) }
+    end
+  end
+
+  describe :commits_straight do
+    subject do
+      compare_straight.commits.map(&:id)
+    end
+
+    it 'has 8 elements' do
+      expect(subject.size).to eq(8)
+    end
+
+    it { is_expected.to include(SeedRepo::Commit::PARENT_ID) }
+    it { is_expected.not_to include(SeedRepo::BigCommit::PARENT_ID) }
+  end
+
+  describe :diffs_straight do
+    subject do
+      compare_straight.diffs.map(&:new_path)
+    end
+
+    it 'has 10 elements' do
+      expect(subject.size).to eq(10)
+    end
+
+    it { is_expected.to include('files/ruby/popen.rb') }
+    it { is_expected.not_to include('LICENSE') }
+  end
+end
diff --git a/spec/lib/gitlab/git/diff_collection_spec.rb b/spec/lib/gitlab/git/diff_collection_spec.rb
new file mode 100644
index 00000000000..067cd370c09
--- /dev/null
+++ b/spec/lib/gitlab/git/diff_collection_spec.rb
@@ -0,0 +1,460 @@
+require "gitlab_git_spec_helper"
+
+describe Gitlab::Git::DiffCollection do
+  subject do
+    Gitlab::Git::DiffCollection.new(
+      iterator,
+      max_files: max_files,
+      max_lines: max_lines,
+      all_diffs: all_diffs,
+      no_collapse: no_collapse
+    )
+  end
+  let(:iterator) { Array.new(file_count, fake_diff(line_length, line_count)) }
+  let(:file_count) { 0 }
+  let(:line_length) { 1 }
+  let(:line_count) { 1 }
+  let(:max_files) { 10 }
+  let(:max_lines) { 100 }
+  let(:all_diffs) { false }
+  let(:no_collapse) { true }
+
+  describe '#to_a' do
+    subject { super().to_a }
+    it { is_expected.to be_kind_of ::Array }
+  end
+
+  describe :decorate! do
+    let(:file_count) { 3 }
+
+    it 'modifies the array in place' do
+      count = 0
+      subject.decorate! { |d| !d.nil? && count += 1 }
+      expect(subject.to_a).to eq([1, 2, 3])
+      expect(count).to eq(3)
+    end
+
+    it 'avoids future iterator iterations' do
+      subject.decorate! { |d| d unless d.nil? }
+
+      expect(iterator).not_to receive(:each)
+
+      subject.overflow?
+    end
+  end
+
+  context 'overflow handling' do
+    context 'adding few enough files' do
+      let(:file_count) { 3 }
+
+      context 'and few enough lines' do
+        let(:line_count) { 10 }
+
+        describe '#overflow?' do
+          subject { super().overflow? }
+          it { is_expected.to be_falsey }
+        end
+
+        describe '#empty?' do
+          subject { super().empty? }
+          it { is_expected.to be_falsey }
+        end
+
+        describe '#real_size' do
+          subject { super().real_size }
+          it { is_expected.to eq('3') }
+        end
+        it { expect(subject.size).to eq(3) }
+
+        context 'when limiting is disabled' do
+          let(:all_diffs) { true }
+
+          describe '#overflow?' do
+            subject { super().overflow? }
+            it { is_expected.to be_falsey }
+          end
+
+          describe '#empty?' do
+            subject { super().empty? }
+            it { is_expected.to be_falsey }
+          end
+
+          describe '#real_size' do
+            subject { super().real_size }
+            it { is_expected.to eq('3') }
+          end
+          it { expect(subject.size).to eq(3) }
+        end
+      end
+
+      context 'and too many lines' do
+        let(:line_count) { 1000 }
+
+        describe '#overflow?' do
+          subject { super().overflow? }
+          it { is_expected.to be_truthy }
+        end
+
+        describe '#empty?' do
+          subject { super().empty? }
+          it { is_expected.to be_falsey }
+        end
+
+        describe '#real_size' do
+          subject { super().real_size }
+          it { is_expected.to eq('0+') }
+        end
+        it { expect(subject.size).to eq(0) }
+
+        context 'when limiting is disabled' do
+          let(:all_diffs) { true }
+
+          describe '#overflow?' do
+            subject { super().overflow? }
+            it { is_expected.to be_falsey }
+          end
+
+          describe '#empty?' do
+            subject { super().empty? }
+            it { is_expected.to be_falsey }
+          end
+
+          describe '#real_size' do
+            subject { super().real_size }
+            it { is_expected.to eq('3') }
+          end
+          it { expect(subject.size).to eq(3) }
+        end
+      end
+    end
+
+    context 'adding too many files' do
+      let(:file_count) { 11 }
+
+      context 'and few enough lines' do
+        let(:line_count) { 1 }
+
+        describe '#overflow?' do
+          subject { super().overflow? }
+          it { is_expected.to be_truthy }
+        end
+
+        describe '#empty?' do
+          subject { super().empty? }
+          it { is_expected.to be_falsey }
+        end
+
+        describe '#real_size' do
+          subject { super().real_size }
+          it { is_expected.to eq('10+') }
+        end
+        it { expect(subject.size).to eq(10) }
+
+        context 'when limiting is disabled' do
+          let(:all_diffs) { true }
+
+          describe '#overflow?' do
+            subject { super().overflow? }
+            it { is_expected.to be_falsey }
+          end
+
+          describe '#empty?' do
+            subject { super().empty? }
+            it { is_expected.to be_falsey }
+          end
+
+          describe '#real_size' do
+            subject { super().real_size }
+            it { is_expected.to eq('11') }
+          end
+          it { expect(subject.size).to eq(11) }
+        end
+      end
+
+      context 'and too many lines' do
+        let(:line_count) { 30 }
+
+        describe '#overflow?' do
+          subject { super().overflow? }
+          it { is_expected.to be_truthy }
+        end
+
+        describe '#empty?' do
+          subject { super().empty? }
+          it { is_expected.to be_falsey }
+        end
+
+        describe '#real_size' do
+          subject { super().real_size }
+          it { is_expected.to eq('3+') }
+        end
+        it { expect(subject.size).to eq(3) }
+
+        context 'when limiting is disabled' do
+          let(:all_diffs) { true }
+
+          describe '#overflow?' do
+            subject { super().overflow? }
+            it { is_expected.to be_falsey }
+          end
+
+          describe '#empty?' do
+            subject { super().empty? }
+            it { is_expected.to be_falsey }
+          end
+
+          describe '#real_size' do
+            subject { super().real_size }
+            it { is_expected.to eq('11') }
+          end
+          it { expect(subject.size).to eq(11) }
+        end
+      end
+    end
+
+    context 'adding exactly the maximum number of files' do
+      let(:file_count) { 10 }
+
+      context 'and few enough lines' do
+        let(:line_count) { 1 }
+
+        describe '#overflow?' do
+          subject { super().overflow? }
+          it { is_expected.to be_falsey }
+        end
+
+        describe '#empty?' do
+          subject { super().empty? }
+          it { is_expected.to be_falsey }
+        end
+
+        describe '#real_size' do
+          subject { super().real_size }
+          it { is_expected.to eq('10') }
+        end
+        it { expect(subject.size).to eq(10) }
+      end
+    end
+
+    context 'adding too many bytes' do
+      let(:file_count) { 10 }
+      let(:line_length) { 5200 }
+
+      describe '#overflow?' do
+        subject { super().overflow? }
+        it { is_expected.to be_truthy }
+      end
+
+      describe '#empty?' do
+        subject { super().empty? }
+        it { is_expected.to be_falsey }
+      end
+
+      describe '#real_size' do
+        subject { super().real_size }
+        it { is_expected.to eq('9+') }
+      end
+      it { expect(subject.size).to eq(9) }
+
+      context 'when limiting is disabled' do
+        let(:all_diffs) { true }
+
+        describe '#overflow?' do
+          subject { super().overflow? }
+          it { is_expected.to be_falsey }
+        end
+
+        describe '#empty?' do
+          subject { super().empty? }
+          it { is_expected.to be_falsey }
+        end
+
+        describe '#real_size' do
+          subject { super().real_size }
+          it { is_expected.to eq('10') }
+        end
+        it { expect(subject.size).to eq(10) }
+      end
+    end
+  end
+
+  describe 'empty collection' do
+    subject { Gitlab::Git::DiffCollection.new([]) }
+
+    describe '#overflow?' do
+      subject { super().overflow? }
+      it { is_expected.to be_falsey }
+    end
+
+    describe '#empty?' do
+      subject { super().empty? }
+      it { is_expected.to be_truthy }
+    end
+
+    describe '#size' do
+      subject { super().size }
+      it { is_expected.to eq(0) }
+    end
+
+    describe '#real_size' do
+      subject { super().real_size }
+      it { is_expected.to eq('0')}
+    end
+  end
+
+  describe :each do
+    context 'when diff are too large' do
+      let(:collection) do
+        Gitlab::Git::DiffCollection.new([{ diff: 'a' * 204800 }])
+      end
+
+      it 'yields Diff instances even when they are too large' do
+        expect { |b| collection.each(&b) }.
+          to yield_with_args(an_instance_of(Gitlab::Git::Diff))
+      end
+
+      it 'prunes diffs that are too large' do
+        diff = nil
+
+        collection.each do |d|
+          diff = d
+        end
+
+        expect(diff.diff).to eq('')
+      end
+    end
+
+    context 'when diff is quite large will collapse by default' do
+      let(:iterator) { [{ diff: 'a' * 20480 }] }
+
+      context 'when no collapse is set' do
+        let(:no_collapse) { true }
+
+        it 'yields Diff instances even when they are quite big' do
+          expect { |b| subject.each(&b) }.
+            to yield_with_args(an_instance_of(Gitlab::Git::Diff))
+        end
+
+        it 'does not prune diffs' do
+          diff = nil
+
+          subject.each do |d|
+            diff = d
+          end
+
+          expect(diff.diff).not_to eq('')
+        end
+      end
+
+      context 'when no collapse is unset' do
+        let(:no_collapse) { false }
+
+        it 'yields Diff instances even when they are quite big' do
+          expect { |b| subject.each(&b) }.
+            to yield_with_args(an_instance_of(Gitlab::Git::Diff))
+        end
+
+        it 'prunes diffs that are quite big' do
+          diff = nil
+
+          subject.each do |d|
+            diff = d
+          end
+
+          expect(diff.diff).to eq('')
+        end
+
+        context 'when go over safe limits on files' do
+          let(:iterator) { [ fake_diff(1, 1) ] * 4 }
+
+          before(:each) do
+            stub_const('Gitlab::Git::DiffCollection::DEFAULT_LIMITS', { max_files: 2, max_lines: max_lines })
+          end
+
+          it 'prunes diffs by default even little ones' do
+            subject.each_with_index do |d, i|
+              if i < 2
+                expect(d.diff).not_to eq('')
+              else # 90 lines
+                expect(d.diff).to eq('')
+              end
+            end
+          end
+        end
+
+        context 'when go over safe limits on lines' do
+          let(:iterator) do
+            [
+              fake_diff(1, 45),
+              fake_diff(1, 45),
+              fake_diff(1, 20480),
+              fake_diff(1, 1)
+            ]
+          end
+
+          before(:each) do
+            stub_const('Gitlab::Git::DiffCollection::DEFAULT_LIMITS', { max_files: max_files, max_lines: 80 })
+          end
+
+          it 'prunes diffs by default even little ones' do
+            subject.each_with_index do |d, i|
+              if i < 2
+                expect(d.diff).not_to eq('')
+              else # 90 lines
+                expect(d.diff).to eq('')
+              end
+            end
+          end
+        end
+
+        context 'when go over safe limits on bytes' do
+          let(:iterator) do
+            [
+              fake_diff(1, 45),
+              fake_diff(1, 45),
+              fake_diff(1, 20480),
+              fake_diff(1, 1)
+            ]
+          end
+
+          before(:each) do
+            stub_const('Gitlab::Git::DiffCollection::DEFAULT_LIMITS', { max_files: max_files, max_lines: 80 })
+          end
+
+          it 'prunes diffs by default even little ones' do
+            subject.each_with_index do |d, i|
+              if i < 2
+                expect(d.diff).not_to eq('')
+              else # > 80 bytes
+                expect(d.diff).to eq('')
+              end
+            end
+          end
+        end
+      end
+
+      context 'when limiting is disabled' do
+        let(:all_diffs) { true }
+
+        it 'yields Diff instances even when they are quite big' do
+          expect { |b| subject.each(&b) }.
+            to yield_with_args(an_instance_of(Gitlab::Git::Diff))
+        end
+
+        it 'does not prune diffs' do
+          diff = nil
+
+          subject.each do |d|
+            diff = d
+          end
+
+          expect(diff.diff).not_to eq('')
+        end
+      end
+    end
+  end
+
+  def fake_diff(line_length, line_count)
+    { 'diff' => "#{'a' * line_length}\n" * line_count }
+  end
+end
diff --git a/spec/lib/gitlab/git/diff_spec.rb b/spec/lib/gitlab/git/diff_spec.rb
new file mode 100644
index 00000000000..7477a769c46
--- /dev/null
+++ b/spec/lib/gitlab/git/diff_spec.rb
@@ -0,0 +1,287 @@
+require "gitlab_git_spec_helper"
+
+describe Gitlab::Git::Diff do
+  let(:repository) { Gitlab::Git::Repository.new(TEST_REPO_PATH) }
+
+  before do
+    @raw_diff_hash = {
+      diff: <<EOT.gsub(/^ {8}/, "").sub(/\n$/, ""),
+        --- a/.gitmodules
+        +++ b/.gitmodules
+        @@ -4,3 +4,6 @@
+         [submodule "gitlab-shell"]
+         \tpath = gitlab-shell
+         \turl = https://github.com/gitlabhq/gitlab-shell.git
+        +[submodule "gitlab-grack"]
+        +	path = gitlab-grack
+        +	url = https://gitlab.com/gitlab-org/gitlab-grack.git
+
+EOT
+      new_path: ".gitmodules",
+      old_path: ".gitmodules",
+      a_mode: '100644',
+      b_mode: '100644',
+      new_file: false,
+      renamed_file: false,
+      deleted_file: false,
+      too_large: false
+    }
+
+    @rugged_diff = repository.rugged.diff("5937ac0a7beb003549fc5fd26fc247adbce4a52e^", "5937ac0a7beb003549fc5fd26fc247adbce4a52e", paths:
+                                          [".gitmodules"]).patches.first
+  end
+
+  describe :new do
+    context 'using a Hash' do
+      context 'with a small diff' do
+        let(:diff) { Gitlab::Git::Diff.new(@raw_diff_hash) }
+
+        it 'initializes the diff' do
+          expect(diff.to_hash).to eq(@raw_diff_hash)
+        end
+
+        it 'does not prune the diff' do
+          expect(diff).not_to be_too_large
+        end
+      end
+
+      context 'using a diff that is too large' do
+        it 'prunes the diff' do
+          diff = Gitlab::Git::Diff.new(diff: 'a' * 204800)
+
+          expect(diff.diff).to be_empty
+          expect(diff).to be_too_large
+        end
+      end
+    end
+
+    context 'using a Rugged::Patch' do
+      context 'with a small diff' do
+        let(:diff) { Gitlab::Git::Diff.new(@rugged_diff) }
+
+        it 'initializes the diff' do
+          expect(diff.to_hash).to eq(@raw_diff_hash.merge(too_large: nil))
+        end
+
+        it 'does not prune the diff' do
+          expect(diff).not_to be_too_large
+        end
+      end
+
+      context 'using a diff that is too large' do
+        it 'prunes the diff' do
+          expect_any_instance_of(String).to receive(:bytesize).
+            and_return(1024 * 1024 * 1024)
+
+          diff = Gitlab::Git::Diff.new(@rugged_diff)
+
+          expect(diff.diff).to be_empty
+          expect(diff).to be_too_large
+        end
+      end
+
+      context 'using a collapsable diff that is too large' do
+        before do
+          # The patch total size is 200, with lines between 21 and 54.
+          # This is a quick-and-dirty way to test this. Ideally, a new patch is
+          # added to the test repo with a size that falls between the real limits.
+          stub_const('Gitlab::Git::Diff::DIFF_SIZE_LIMIT', 150)
+          stub_const('Gitlab::Git::Diff::DIFF_COLLAPSE_LIMIT', 100)
+        end
+
+        it 'prunes the diff as a large diff instead of as a collapsed diff' do
+          diff = Gitlab::Git::Diff.new(@rugged_diff, collapse: true)
+
+          expect(diff.diff).to be_empty
+          expect(diff).to be_too_large
+          expect(diff).not_to be_collapsed
+        end
+      end
+
+      context 'using a large binary diff' do
+        it 'does not prune the diff' do
+          expect_any_instance_of(Rugged::Diff::Delta).to receive(:binary?).
+            and_return(true)
+
+          diff = Gitlab::Git::Diff.new(@rugged_diff)
+
+          expect(diff.diff).not_to be_empty
+        end
+      end
+    end
+  end
+
+  describe 'straight diffs' do
+    let(:options) { { straight: true } }
+    let(:diffs) { Gitlab::Git::Diff.between(repository, 'feature', 'master', options) }
+    subject { diffs }
+
+    describe '#size' do
+      subject { super().size }
+
+      it { is_expected.to eq(24) }
+    end
+
+    context :diff do
+      subject { diffs.first }
+
+      it { should be_kind_of Gitlab::Git::Diff }
+      its(:new_path) { should == '.DS_Store' }
+      its(:diff) { should include 'Binary files /dev/null and b/.DS_Store differ' }
+    end
+  end
+
+  describe :between do
+    let(:diffs) { Gitlab::Git::Diff.between(repository, 'feature', 'master') }
+    subject { diffs }
+
+    it { is_expected.to be_kind_of Gitlab::Git::DiffCollection }
+
+    describe '#size' do
+      subject { super().size }
+
+      it { is_expected.to eq(1) }
+    end
+
+    context :diff do
+      subject { diffs.first }
+
+      it { is_expected.to be_kind_of Gitlab::Git::Diff }
+
+      describe '#new_path' do
+        subject { super().new_path }
+
+        it { is_expected.to eq('files/ruby/feature.rb') }
+      end
+
+      describe '#diff' do
+        subject { super().diff }
+
+        it { is_expected.to include '+class Feature' }
+      end
+    end
+  end
+
+  describe :filter_diff_options do
+    let(:options) { { max_size: 100, invalid_opt: true } }
+
+    context "without default options" do
+      let(:filtered_options) { Gitlab::Git::Diff.filter_diff_options(options) }
+
+      it "should filter invalid options" do
+        expect(filtered_options).not_to have_key(:invalid_opt)
+      end
+    end
+
+    context "with default options" do
+      let(:filtered_options) do
+        default_options = { max_size: 5, bad_opt: 1, ignore_whitespace: true }
+        Gitlab::Git::Diff.filter_diff_options(options, default_options)
+      end
+
+      it "should filter invalid options" do
+        expect(filtered_options).not_to have_key(:invalid_opt)
+        expect(filtered_options).not_to have_key(:bad_opt)
+      end
+
+      it "should merge with default options" do
+        expect(filtered_options).to have_key(:ignore_whitespace)
+      end
+
+      it "should override default options" do
+        expect(filtered_options).to have_key(:max_size)
+        expect(filtered_options[:max_size]).to eq(100)
+      end
+    end
+  end
+
+  describe :submodule? do
+    before do
+      commit = repository.lookup('5937ac0a7beb003549fc5fd26fc247adbce4a52e')
+      @diffs = commit.parents[0].diff(commit).patches
+    end
+
+    it { expect(Gitlab::Git::Diff.new(@diffs[0]).submodule?).to eq(false) }
+    it { expect(Gitlab::Git::Diff.new(@diffs[1]).submodule?).to eq(true) }
+  end
+
+  describe :line_count do
+    subject { Gitlab::Git::Diff.new(@rugged_diff) }
+
+    describe '#line_count' do
+      subject { super().line_count }
+      it { is_expected.to eq(9) }
+    end
+
+    its(:line_count) { should eq(9) }
+  end
+
+  describe :too_large? do
+    it 'returns true for a diff that is too large' do
+      diff = Gitlab::Git::Diff.new(diff: 'a' * 204800)
+
+      expect(diff.too_large?).to eq(true)
+    end
+
+    it 'returns false for a diff that is small enough' do
+      diff = Gitlab::Git::Diff.new(diff: 'a')
+
+      expect(diff.too_large?).to eq(false)
+    end
+
+    it 'returns true for a diff that was explicitly marked as being too large' do
+      diff = Gitlab::Git::Diff.new(diff: 'a')
+
+      diff.prune_large_diff!
+
+      expect(diff.too_large?).to eq(true)
+    end
+  end
+
+  describe :collapsed? do
+    it 'returns false by default even on quite big diff' do
+      diff = Gitlab::Git::Diff.new(diff: 'a' * 20480)
+
+      expect(diff.collapsed?).to eq(false)
+    end
+
+    it 'returns false by default for a diff that is small enough' do
+      diff = Gitlab::Git::Diff.new(diff: 'a')
+
+      expect(diff.collapsed?).to eq(false)
+    end
+
+    it 'returns true for a diff that was explicitly marked as being collapsed' do
+      diff = Gitlab::Git::Diff.new(diff: 'a')
+
+      diff.prune_collapsed_diff!
+
+      expect(diff.collapsed?).to eq(true)
+    end
+  end
+
+  describe :collapsible? do
+    it 'returns true for a diff that is quite large' do
+      diff = Gitlab::Git::Diff.new(diff: 'a' * 20480)
+
+      expect(diff.collapsible?).to eq(true)
+    end
+
+    it 'returns false for a diff that is small enough' do
+      diff = Gitlab::Git::Diff.new(diff: 'a')
+
+      expect(diff.collapsible?).to eq(false)
+    end
+  end
+
+  describe :prune_collapsed_diff! do
+    it 'prunes the diff' do
+      diff = Gitlab::Git::Diff.new(diff: "foo\nbar")
+
+      diff.prune_collapsed_diff!
+
+      expect(diff.diff).to eq('')
+      expect(diff.line_count).to eq(0)
+    end
+  end
+end
diff --git a/spec/lib/gitlab/git/encoding_helper_spec.rb b/spec/lib/gitlab/git/encoding_helper_spec.rb
new file mode 100644
index 00000000000..b31e871708a
--- /dev/null
+++ b/spec/lib/gitlab/git/encoding_helper_spec.rb
@@ -0,0 +1,84 @@
+require "gitlab_git_spec_helper"
+
+describe Gitlab::Git::EncodingHelper do
+  let(:ext_class) { Class.new { extend Gitlab::Git::EncodingHelper } }
+  let(:binary_string) { Rails.root.join('spec', 'support', 'gitlab_git', 'gitlab_logo.png').to_s }
+
+  describe '#encode!' do
+    [
+      [
+        'leaves ascii only string as is',
+        'ascii only string',
+        'ascii only string'
+      ],
+      [
+        'leaves valid utf8 string as is',
+        'multibyte string №∑∉',
+        'multibyte string №∑∉'
+      ],
+      [
+        'removes invalid bytes from ASCII-8bit encoded multibyte string. This can occur when a git diff match line truncates in the middle of a multibyte character. This occurs after the second word in this example. The test string is as short as we can get while still triggering the error condition when not looking at `detect[:confidence]`.',
+        "mu ns\xC3\n Lorem ipsum dolor sit amet, consectetur adipisicing ut\xC3\xA0y\xC3\xB9abcd\xC3\xB9efg kia elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non p\n {: .normal_pn}\n \n-Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in\n# *Lorem ipsum\xC3\xB9l\xC3\xB9l\xC3\xA0 dolor\xC3\xB9k\xC3\xB9 sit\xC3\xA8b\xC3\xA8 N\xC3\xA8 amet b\xC3\xA0d\xC3\xAC*\n+# *consectetur\xC3\xB9l\xC3\xB9l\xC3\xA0 adipisicing\xC3\xB9k\xC3\xB9 elit\xC3\xA8b\xC3\xA8 N\xC3\xA8 sed do\xC3\xA0d\xC3\xAC*{: .italic .smcaps}\n \n \xEF\x9B\xA1 eiusmod tempor incididunt, ut\xC3\xAAn\xC3\xB9 labore et dolore. Tw\xC4\x83nj\xC3\xAC magna aliqua. Ut enim ad minim veniam\n {: .normal}\n@@ -9,5 +9,5 @@ quis nostrud\xC3\xAAt\xC3\xB9 exercitiation ullamco laboris m\xC3\xB9s\xC3\xB9k\xC3\xB9abc\xC3\xB9 nisi ".force_encoding('ASCII-8BIT'),
+        "mu ns\n Lorem ipsum dolor sit amet, consectetur adipisicing ut\xC3\xA0y\xC3\xB9abcd\xC3\xB9efg kia elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non p\n {: .normal_pn}\n \n-Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in\n# *Lorem ipsum\xC3\xB9l\xC3\xB9l\xC3\xA0 dolor\xC3\xB9k\xC3\xB9 sit\xC3\xA8b\xC3\xA8 N\xC3\xA8 amet b\xC3\xA0d\xC3\xAC*\n+# *consectetur\xC3\xB9l\xC3\xB9l\xC3\xA0 adipisicing\xC3\xB9k\xC3\xB9 elit\xC3\xA8b\xC3\xA8 N\xC3\xA8 sed do\xC3\xA0d\xC3\xAC*{: .italic .smcaps}\n \n \xEF\x9B\xA1 eiusmod tempor incididunt, ut\xC3\xAAn\xC3\xB9 labore et dolore. Tw\xC4\x83nj\xC3\xAC magna aliqua. Ut enim ad minim veniam\n {: .normal}\n@@ -9,5 +9,5 @@ quis nostrud\xC3\xAAt\xC3\xB9 exercitiation ullamco laboris m\xC3\xB9s\xC3\xB9k\xC3\xB9abc\xC3\xB9 nisi ",
+      ],
+    ].each do |description, test_string, xpect|
+      it description do
+        expect(ext_class.encode!(test_string)).to eq(xpect)
+      end
+    end
+
+    it 'leaves binary string as is' do
+      expect(ext_class.encode!(binary_string)).to eq(binary_string)
+    end
+  end
+
+  describe '#encode_utf8' do
+    [
+      [
+        "encodes valid utf8 encoded string to utf8",
+        "λ, λ, λ".encode("UTF-8"),
+        "λ, λ, λ".encode("UTF-8"),
+      ],
+      [
+        "encodes valid ASCII-8BIT encoded string to utf8",
+        "ascii only".encode("ASCII-8BIT"),
+        "ascii only".encode("UTF-8"),
+      ],
+      [
+        "encodes valid ISO-8859-1 encoded string to utf8",
+        "Rüby ist eine Programmiersprache. Wir verlängern den text damit ICU die Sprache erkennen kann.".encode("ISO-8859-1", "UTF-8"),
+        "Rüby ist eine Programmiersprache. Wir verlängern den text damit ICU die Sprache erkennen kann.".encode("UTF-8"),
+      ],
+    ].each do |description, test_string, xpect|
+      it description do
+        r = ext_class.encode_utf8(test_string.force_encoding('UTF-8'))
+        expect(r).to eq(xpect)
+        expect(r.encoding.name).to eq('UTF-8')
+      end
+    end
+  end
+
+  describe '#clean' do
+    [
+      [
+        'leaves ascii only string as is',
+        'ascii only string',
+        'ascii only string'
+      ],
+      [
+        'leaves valid utf8 string as is',
+        'multibyte string №∑∉',
+        'multibyte string №∑∉'
+      ],
+      [
+        'removes invalid bytes from ASCII-8bit encoded multibyte string.',
+        "Lorem ipsum\xC3\n dolor sit amet, xy\xC3\xA0y\xC3\xB9abcd\xC3\xB9efg".force_encoding('ASCII-8BIT'),
+        "Lorem ipsum\n dolor sit amet, xyàyùabcdùefg",
+      ],
+    ].each do |description, test_string, xpect|
+      it description do
+        expect(ext_class.encode!(test_string)).to eq(xpect)
+      end
+    end
+  end
+end
diff --git a/spec/lib/gitlab/git/hook_spec.rb b/spec/lib/gitlab/git/hook_spec.rb
index d1f947b6850..750767fa708 100644
--- a/spec/lib/gitlab/git/hook_spec.rb
+++ b/spec/lib/gitlab/git/hook_spec.rb
@@ -1,4 +1,4 @@
-require 'spec_helper'
+require "gitlab_git_spec_helper"
 require 'fileutils'
 
 describe Gitlab::Git::Hook, lib: true do
diff --git a/spec/lib/gitlab/git/repository_spec.rb b/spec/lib/gitlab/git/repository_spec.rb
new file mode 100644
index 00000000000..eb2f692360d
--- /dev/null
+++ b/spec/lib/gitlab/git/repository_spec.rb
@@ -0,0 +1,1144 @@
+require "gitlab_git_spec_helper"
+
+describe Gitlab::Git::Repository do
+  include Gitlab::Git::EncodingHelper
+
+  let(:repository) { Gitlab::Git::Repository.new(TEST_REPO_PATH) }
+
+  describe "Respond to" do
+    subject { repository }
+
+    it { is_expected.to respond_to(:raw) }
+    it { is_expected.to respond_to(:rugged) }
+    it { is_expected.to respond_to(:root_ref) }
+    it { is_expected.to respond_to(:tags) }
+  end
+
+  describe "#discover_default_branch" do
+    let(:master) { 'master' }
+    let(:feature) { 'feature' }
+    let(:feature2) { 'feature2' }
+
+    it "returns 'master' when master exists" do
+      expect(repository).to receive(:branch_names).at_least(:once).and_return([feature, master])
+      expect(repository.discover_default_branch).to eq('master')
+    end
+
+    it "returns non-master when master exists but default branch is set to something else" do
+      File.write(File.join(repository.path, 'HEAD'), 'ref: refs/heads/feature')
+      expect(repository).to receive(:branch_names).at_least(:once).and_return([feature, master])
+      expect(repository.discover_default_branch).to eq('feature')
+      File.write(File.join(repository.path, 'HEAD'), 'ref: refs/heads/master')
+    end
+
+    it "returns a non-master branch when only one exists" do
+      expect(repository).to receive(:branch_names).at_least(:once).and_return([feature])
+      expect(repository.discover_default_branch).to eq('feature')
+    end
+
+    it "returns a non-master branch when more than one exists and master does not" do
+      expect(repository).to receive(:branch_names).at_least(:once).and_return([feature, feature2])
+      expect(repository.discover_default_branch).to eq('feature')
+    end
+
+    it "returns nil when no branch exists" do
+      expect(repository).to receive(:branch_names).at_least(:once).and_return([])
+      expect(repository.discover_default_branch).to be_nil
+    end
+  end
+
+  describe :branch_names do
+    subject { repository.branch_names }
+
+    it 'has SeedRepo::Repo::BRANCHES.size elements' do
+      expect(subject.size).to eq(SeedRepo::Repo::BRANCHES.size)
+    end
+    it { is_expected.to include("master") }
+    it { is_expected.not_to include("branch-from-space") }
+  end
+
+  describe :tag_names do
+    subject { repository.tag_names }
+
+    it { is_expected.to be_kind_of Array }
+    it 'has SeedRepo::Repo::TAGS.size elements' do
+      expect(subject.size).to eq(SeedRepo::Repo::TAGS.size)
+    end
+
+    describe '#last' do
+      subject { super().last }
+      it { is_expected.to eq("v1.2.1") }
+    end
+    it { is_expected.to include("v1.0.0") }
+    it { is_expected.not_to include("v5.0.0") }
+  end
+
+  shared_examples 'archive check' do |extenstion|
+    it { expect(metadata['ArchivePath']).to match(/tmp\/gitlab-git-test.git\/gitlab-git-test-master-#{SeedRepo::LastCommit::ID}/) }
+    it { expect(metadata['ArchivePath']).to end_with extenstion }
+  end
+
+  describe :archive do
+    let(:metadata) { repository.archive_metadata('master', '/tmp') }
+
+    it_should_behave_like 'archive check', '.tar.gz'
+  end
+
+  describe :archive_zip do
+    let(:metadata) { repository.archive_metadata('master', '/tmp', 'zip') }
+
+    it_should_behave_like 'archive check', '.zip'
+  end
+
+  describe :archive_bz2 do
+    let(:metadata) { repository.archive_metadata('master', '/tmp', 'tbz2') }
+
+    it_should_behave_like 'archive check', '.tar.bz2'
+  end
+
+  describe :archive_fallback do
+    let(:metadata) { repository.archive_metadata('master', '/tmp', 'madeup') }
+
+    it_should_behave_like 'archive check', '.tar.gz'
+  end
+
+  describe :size do
+    subject { repository.size }
+
+    it { is_expected.to be < 2 }
+  end
+
+  describe :has_commits? do
+    it { expect(repository.has_commits?).to be_truthy }
+  end
+
+  describe :empty? do
+    it { expect(repository.empty?).to be_falsey }
+  end
+
+  describe :bare? do
+    it { expect(repository.bare?).to be_truthy }
+  end
+
+  describe :heads do
+    let(:heads) { repository.heads }
+    subject { heads }
+
+    it { is_expected.to be_kind_of Array }
+
+    describe '#size' do
+      subject { super().size }
+      it { is_expected.to eq(SeedRepo::Repo::BRANCHES.size) }
+    end
+
+    context :head do
+      subject { heads.first }
+
+      describe '#name' do
+        subject { super().name }
+        it { is_expected.to eq("feature") }
+      end
+
+      context :commit do
+        subject { heads.first.dereferenced_target.sha }
+
+        it { is_expected.to eq("0b4bc9a49b562e85de7cc9e834518ea6828729b9") }
+      end
+    end
+  end
+
+  describe :ref_names do
+    let(:ref_names) { repository.ref_names }
+    subject { ref_names }
+
+    it { is_expected.to be_kind_of Array }
+
+    describe '#first' do
+      subject { super().first }
+      it { is_expected.to eq('feature') }
+    end
+
+    describe '#last' do
+      subject { super().last }
+      it { is_expected.to eq('v1.2.1') }
+    end
+  end
+
+  describe :search_files do
+    let(:results) { repository.search_files('rails', 'master') }
+    subject { results }
+
+    it { is_expected.to be_kind_of Array }
+
+    describe '#first' do
+      subject { super().first }
+      it { is_expected.to be_kind_of Gitlab::Git::BlobSnippet }
+    end
+
+    context 'blob result' do
+      subject { results.first }
+
+      describe '#ref' do
+        subject { super().ref }
+        it { is_expected.to eq('master') }
+      end
+
+      describe '#filename' do
+        subject { super().filename }
+        it { is_expected.to eq('CHANGELOG') }
+      end
+
+      describe '#startline' do
+        subject { super().startline }
+        it { is_expected.to eq(35) }
+      end
+
+      describe '#data' do
+        subject { super().data }
+        it { is_expected.to include "Ability to filter by multiple labels" }
+      end
+    end
+  end
+
+  context :submodules do
+    let(:repository) { Gitlab::Git::Repository.new(TEST_REPO_PATH) }
+
+    context 'where repo has submodules' do
+      let(:submodules) { repository.submodules('master') }
+      let(:submodule) { submodules.first }
+
+      it { expect(submodules).to be_kind_of Hash }
+      it { expect(submodules.empty?).to be_falsey }
+
+      it 'should have valid data' do
+        expect(submodule).to eq([
+          "six", {
+            "id" => "409f37c4f05865e4fb208c771485f211a22c4c2d",
+            "path" => "six",
+            "url" => "git://github.com/randx/six.git"
+          }
+        ])
+      end
+
+      it 'should handle nested submodules correctly' do
+        nested = submodules['nested/six']
+        expect(nested['path']).to eq('nested/six')
+        expect(nested['url']).to eq('git://github.com/randx/six.git')
+        expect(nested['id']).to eq('24fb71c79fcabc63dfd8832b12ee3bf2bf06b196')
+      end
+
+      it 'should handle deeply nested submodules correctly' do
+        nested = submodules['deeper/nested/six']
+        expect(nested['path']).to eq('deeper/nested/six')
+        expect(nested['url']).to eq('git://github.com/randx/six.git')
+        expect(nested['id']).to eq('24fb71c79fcabc63dfd8832b12ee3bf2bf06b196')
+      end
+
+      it 'should not have an entry for an invalid submodule' do
+        expect(submodules).not_to have_key('invalid/path')
+      end
+
+      it 'should not have an entry for an uncommited submodule dir' do
+        submodules = repository.submodules('fix-existing-submodule-dir')
+        expect(submodules).not_to have_key('submodule-existing-dir')
+      end
+
+      it 'should handle tags correctly' do
+        submodules = repository.submodules('v1.2.1')
+        submodule = submodules.first
+        expect(submodule).to eq([
+          "six", {
+            "id" => "409f37c4f05865e4fb208c771485f211a22c4c2d",
+            "path" => "six",
+            "url" => "git://github.com/randx/six.git"
+          }
+        ])
+      end
+    end
+
+    context 'where repo doesn\'t have submodules' do
+      let(:submodules) { repository.submodules('6d39438') }
+      it 'should return an empty hash' do
+        expect(submodules).to be_empty
+      end
+    end
+  end
+
+  describe :commit_count do
+    it { expect(repository.commit_count("master")).to eq(25) }
+    it { expect(repository.commit_count("feature")).to eq(9) }
+  end
+
+  describe "#reset" do
+    change_path = File.join(TEST_NORMAL_REPO_PATH, "CHANGELOG")
+    untracked_path = File.join(TEST_NORMAL_REPO_PATH, "UNTRACKED")
+    tracked_path = File.join(TEST_NORMAL_REPO_PATH, "files", "ruby", "popen.rb")
+
+    change_text = "New changelog text"
+    untracked_text = "This file is untracked"
+
+    reset_commit = SeedRepo::LastCommit::ID
+
+    context "--hard" do
+      before(:all) do
+        # Modify a tracked file
+        File.open(change_path, "w") do |f|
+          f.write(change_text)
+        end
+
+        # Add an untracked file to the working directory
+        File.open(untracked_path, "w") do |f|
+          f.write(untracked_text)
+        end
+
+        @normal_repo = Gitlab::Git::Repository.new(TEST_NORMAL_REPO_PATH)
+        @normal_repo.reset("HEAD", :hard)
+      end
+
+      it "should replace the working directory with the content of the index" do
+        File.open(change_path, "r") do |f|
+          expect(f.each_line.first).not_to eq(change_text)
+        end
+
+        File.open(tracked_path, "r") do |f|
+          expect(f.each_line.to_a[8]).to include('raise RuntimeError, "System commands')
+        end
+      end
+
+      it "should not touch untracked files" do
+        expect(File.exist?(untracked_path)).to be_truthy
+      end
+
+      it "should move the HEAD to the correct commit" do
+        new_head = @normal_repo.rugged.head.target.oid
+        expect(new_head).to eq(reset_commit)
+      end
+
+      it "should move the tip of the master branch to the correct commit" do
+        new_tip = @normal_repo.rugged.references["refs/heads/master"].
+          target.oid
+
+        expect(new_tip).to eq(reset_commit)
+      end
+
+      after(:all) do
+        # Fast-forward to the original HEAD
+        FileUtils.rm_rf(TEST_NORMAL_REPO_PATH)
+        ensure_seeds
+      end
+    end
+  end
+
+  describe "#checkout" do
+    new_branch = "foo_branch"
+
+    context "-b" do
+      before(:all) do
+        @normal_repo = Gitlab::Git::Repository.new(TEST_NORMAL_REPO_PATH)
+        @normal_repo.checkout(new_branch, { b: true }, "origin/feature")
+      end
+
+      it "should create a new branch" do
+        expect(@normal_repo.rugged.branches[new_branch]).not_to be_nil
+      end
+
+      it "should move the HEAD to the correct commit" do
+        expect(@normal_repo.rugged.head.target.oid).to(
+          eq(@normal_repo.rugged.branches["origin/feature"].target.oid)
+        )
+      end
+
+      it "should refresh the repo's #heads collection" do
+        head_names = @normal_repo.heads.map { |h| h.name }
+        expect(head_names).to include(new_branch)
+      end
+
+      after(:all) do
+        FileUtils.rm_rf(TEST_NORMAL_REPO_PATH)
+        ensure_seeds
+      end
+    end
+
+    context "without -b" do
+      context "and specifying a nonexistent branch" do
+        it "should not do anything" do
+          normal_repo = Gitlab::Git::Repository.new(TEST_NORMAL_REPO_PATH)
+
+          expect { normal_repo.checkout(new_branch) }.to raise_error(Rugged::ReferenceError)
+          expect(normal_repo.rugged.branches[new_branch]).to be_nil
+          expect(normal_repo.rugged.head.target.oid).to(
+            eq(normal_repo.rugged.branches["master"].target.oid)
+          )
+
+          head_names = normal_repo.heads.map { |h| h.name }
+          expect(head_names).not_to include(new_branch)
+        end
+
+        after(:all) do
+          FileUtils.rm_rf(TEST_NORMAL_REPO_PATH)
+          ensure_seeds
+        end
+      end
+
+      context "and with a valid branch" do
+        before(:all) do
+          @normal_repo = Gitlab::Git::Repository.new(TEST_NORMAL_REPO_PATH)
+          @normal_repo.rugged.branches.create("feature", "origin/feature")
+          @normal_repo.checkout("feature")
+        end
+
+        it "should move the HEAD to the correct commit" do
+          expect(@normal_repo.rugged.head.target.oid).to(
+            eq(@normal_repo.rugged.branches["feature"].target.oid)
+          )
+        end
+
+        it "should update the working directory" do
+          File.open(File.join(TEST_NORMAL_REPO_PATH, ".gitignore"), "r") do |f|
+            expect(f.read.each_line.to_a).not_to include(".DS_Store\n")
+          end
+        end
+
+        after(:all) do
+          FileUtils.rm_rf(TEST_NORMAL_REPO_PATH)
+          ensure_seeds
+        end
+      end
+    end
+  end
+
+  describe "#delete_branch" do
+    before(:all) do
+      @repo = Gitlab::Git::Repository.new(TEST_MUTABLE_REPO_PATH)
+      @repo.delete_branch("feature")
+    end
+
+    it "should remove the branch from the repo" do
+      expect(@repo.rugged.branches["feature"]).to be_nil
+    end
+
+    it "should update the repo's #heads collection" do
+      expect(@repo.heads).not_to include("feature")
+    end
+
+    after(:all) do
+      FileUtils.rm_rf(TEST_MUTABLE_REPO_PATH)
+      ensure_seeds
+    end
+  end
+
+  describe "#create_branch" do
+    before(:all) do
+      @repo = Gitlab::Git::Repository.new(TEST_MUTABLE_REPO_PATH)
+    end
+
+    it "should create a new branch" do
+      expect(@repo.create_branch('new_branch', 'master')).not_to be_nil
+    end
+
+    it "should create a new branch with the right name" do
+      expect(@repo.create_branch('another_branch', 'master').name).to eq('another_branch')
+    end
+
+    it "should fail if we create an existing branch" do
+      @repo.create_branch('duplicated_branch', 'master')
+      expect{@repo.create_branch('duplicated_branch', 'master')}.to raise_error("Branch duplicated_branch already exists")
+    end
+
+    it "should fail if we create a branch from a non existing ref" do
+      expect{@repo.create_branch('branch_based_in_wrong_ref', 'master_2_the_revenge')}.to raise_error("Invalid reference master_2_the_revenge")
+    end
+
+    after(:all) do
+      FileUtils.rm_rf(TEST_MUTABLE_REPO_PATH)
+      ensure_seeds
+    end
+  end
+
+  describe "#remote_names" do
+    let(:remotes) { repository.remote_names }
+
+    it "should have one entry: 'origin'" do
+      expect(remotes.size).to eq(1)
+      expect(remotes.first).to eq("origin")
+    end
+  end
+
+  describe "#refs_hash" do
+    let(:refs) { repository.refs_hash }
+
+    it "should have as many entries as branches and tags" do
+      expected_refs = SeedRepo::Repo::BRANCHES + SeedRepo::Repo::TAGS
+      # We flatten in case a commit is pointed at by more than one branch and/or tag
+      expect(refs.values.flatten.size).to eq(expected_refs.size)
+    end
+  end
+
+  describe "#remote_delete" do
+    before(:all) do
+      @repo = Gitlab::Git::Repository.new(TEST_MUTABLE_REPO_PATH)
+      @repo.remote_delete("expendable")
+    end
+
+    it "should remove the remote" do
+      expect(@repo.rugged.remotes).not_to include("expendable")
+    end
+
+    after(:all) do
+      FileUtils.rm_rf(TEST_MUTABLE_REPO_PATH)
+      ensure_seeds
+    end
+  end
+
+  describe "#remote_add" do
+    before(:all) do
+      @repo = Gitlab::Git::Repository.new(TEST_MUTABLE_REPO_PATH)
+      @repo.remote_add("new_remote", SeedHelper::GITLAB_URL)
+    end
+
+    it "should add the remote" do
+      expect(@repo.rugged.remotes.each_name.to_a).to include("new_remote")
+    end
+
+    after(:all) do
+      FileUtils.rm_rf(TEST_MUTABLE_REPO_PATH)
+      ensure_seeds
+    end
+  end
+
+  describe "#remote_update" do
+    before(:all) do
+      @repo = Gitlab::Git::Repository.new(TEST_MUTABLE_REPO_PATH)
+      @repo.remote_update("expendable", url: TEST_NORMAL_REPO_PATH)
+    end
+
+    it "should add the remote" do
+      expect(@repo.rugged.remotes["expendable"].url).to(
+        eq(TEST_NORMAL_REPO_PATH)
+      )
+    end
+
+    after(:all) do
+      FileUtils.rm_rf(TEST_MUTABLE_REPO_PATH)
+      ensure_seeds
+    end
+  end
+
+  describe "#diff_text" do
+    let(:repo) { Gitlab::Git::Repository.new(TEST_MUTABLE_REPO_PATH) }
+
+    it "should contain the same diffs as #diff" do
+      diff_text = repo.diff_text("master", "feature")
+      diff_text = encode_utf8(diff_text)
+      repo.diff("master", "feature").each do |single_diff|
+        expect(diff_text.include?(single_diff.diff)).to be_truthy
+      end
+    end
+
+    it "should restrict its output to +paths+" do
+      diff_text = repo.diff_text("master", "feature", nil, "files")
+      repo.rugged.diff("master", "feature").each_delta do |delta|
+        path = delta.old_file[:path]
+        match_text = "diff --git a/#{path}"
+
+        if path.match(/^files/)
+          expect(diff_text).to include(match_text)
+        else
+          expect(diff_text).not_to include(match_text)
+        end
+      end
+    end
+  end
+
+  describe "#log" do
+    commit_with_old_name = nil
+    commit_with_new_name = nil
+    rename_commit = nil
+
+    before(:all) do
+      # Add new commits so that there's a renamed file in the commit history
+      repo = Gitlab::Git::Repository.new(TEST_REPO_PATH).rugged
+
+      commit_with_old_name = new_commit_edit_old_file(repo)
+      rename_commit = new_commit_move_file(repo)
+      commit_with_new_name = new_commit_edit_new_file(repo)
+    end
+
+    context "where 'follow' == true" do
+      options = { ref: "master", follow: true }
+
+      context "and 'path' is a directory" do
+        let(:log_commits) do
+          repository.log(options.merge(path: "encoding"))
+        end
+
+        it "should not follow renames" do
+          expect(log_commits).to include(commit_with_new_name)
+          expect(log_commits).to include(rename_commit)
+          expect(log_commits).not_to include(commit_with_old_name)
+        end
+      end
+
+      context "and 'path' is a file that matches the new filename" do
+        let(:log_commits) do
+          repository.log(options.merge(path: "encoding/CHANGELOG"))
+        end
+
+        it "should follow renames" do
+          expect(log_commits).to include(commit_with_new_name)
+          expect(log_commits).to include(rename_commit)
+          expect(log_commits).to include(commit_with_old_name)
+        end
+      end
+
+      context "and 'path' is a file that matches the old filename" do
+        let(:log_commits) do
+          repository.log(options.merge(path: "CHANGELOG"))
+        end
+
+        it "should not follow renames" do
+          expect(log_commits).to include(commit_with_old_name)
+          expect(log_commits).to include(rename_commit)
+          expect(log_commits).not_to include(commit_with_new_name)
+        end
+      end
+
+      context "unknown ref" do
+        let(:log_commits) { repository.log(options.merge(ref: 'unknown')) }
+
+        it "should return empty" do
+          expect(log_commits).to eq([])
+        end
+      end
+    end
+
+    context "where 'follow' == false" do
+      options = { follow: false }
+
+      context "and 'path' is a directory" do
+        let(:log_commits) do
+          repository.log(options.merge(path: "encoding"))
+        end
+
+        it "should not follow renames" do
+          expect(log_commits).to include(commit_with_new_name)
+          expect(log_commits).to include(rename_commit)
+          expect(log_commits).not_to include(commit_with_old_name)
+        end
+      end
+
+      context "and 'path' is a file that matches the new filename" do
+        let(:log_commits) do
+          repository.log(options.merge(path: "encoding/CHANGELOG"))
+        end
+
+        it "should not follow renames" do
+          expect(log_commits).to include(commit_with_new_name)
+          expect(log_commits).to include(rename_commit)
+          expect(log_commits).not_to include(commit_with_old_name)
+        end
+      end
+
+      context "and 'path' is a file that matches the old filename" do
+        let(:log_commits) do
+          repository.log(options.merge(path: "CHANGELOG"))
+        end
+
+        it "should not follow renames" do
+          expect(log_commits).to include(commit_with_old_name)
+          expect(log_commits).to include(rename_commit)
+          expect(log_commits).not_to include(commit_with_new_name)
+        end
+      end
+
+      context "and 'path' includes a directory that used to be a file" do
+        let(:log_commits) do
+          repository.log(options.merge(ref: "refs/heads/fix-blob-path", path: "files/testdir/file.txt"))
+        end
+
+        it "should return a list of commits" do
+          expect(log_commits.size).to eq(1)
+        end
+      end
+    end
+
+    context "compare results between log_by_walk and log_by_shell" do
+      let(:options) { { ref: "master" } }
+      let(:commits_by_walk) { repository.log(options).map(&:oid) }
+      let(:commits_by_shell) { repository.log(options.merge({ disable_walk: true })).map(&:oid) }
+
+      it { expect(commits_by_walk).to eq(commits_by_shell) }
+
+      context "with limit" do
+        let(:options) { { ref: "master", limit: 1 } }
+
+        it { expect(commits_by_walk).to eq(commits_by_shell) }
+      end
+
+      context "with offset" do
+        let(:options) { { ref: "master", offset: 1 } }
+
+        it { expect(commits_by_walk).to eq(commits_by_shell) }
+      end
+
+      context "with skip_merges" do
+        let(:options) { { ref: "master", skip_merges: true } }
+
+        it { expect(commits_by_walk).to eq(commits_by_shell) }
+      end
+
+      context "with path" do
+        let(:options) { { ref: "master", path: "encoding" } }
+
+        it { expect(commits_by_walk).to eq(commits_by_shell) }
+
+        context "with follow" do
+          let(:options) { { ref: "master", path: "encoding", follow: true } }
+
+          it { expect(commits_by_walk).to eq(commits_by_shell) }
+        end
+      end
+    end
+
+    context "where provides 'after' timestamp" do
+      options = { after: Time.iso8601('2014-03-03T20:15:01+00:00') }
+
+      it "should returns commits on or after that timestamp" do
+        commits = repository.log(options)
+
+        expect(commits.size).to be > 0
+        satisfy do
+          commits.all? { |commit| commit.created_at >= options[:after] }
+        end
+      end
+    end
+
+    context "where provides 'before' timestamp" do
+      options = { before: Time.iso8601('2014-03-03T20:15:01+00:00') }
+
+      it "should returns commits on or before that timestamp" do
+        commits = repository.log(options)
+
+        expect(commits.size).to be > 0
+        satisfy do
+          commits.all? { |commit| commit.created_at <= options[:before] }
+        end
+      end
+    end
+
+    after(:all) do
+      # Erase our commits so other tests get the original repo
+      repo = Gitlab::Git::Repository.new(TEST_REPO_PATH).rugged
+      repo.references.update("refs/heads/master", SeedRepo::LastCommit::ID)
+    end
+  end
+
+  describe "#commits_between" do
+    context 'two SHAs' do
+      let(:first_sha) { 'b0e52af38d7ea43cf41d8a6f2471351ac036d6c9' }
+      let(:second_sha) { '0e50ec4d3c7ce42ab74dda1d422cb2cbffe1e326' }
+
+      it 'returns the number of commits between' do
+        expect(repository.commits_between(first_sha, second_sha).count).to eq(3)
+      end
+    end
+
+    context 'SHA and master branch' do
+      let(:sha) { 'b0e52af38d7ea43cf41d8a6f2471351ac036d6c9' }
+      let(:branch) { 'master' }
+
+      it 'returns the number of commits between a sha and a branch' do
+        expect(repository.commits_between(sha, branch).count).to eq(5)
+      end
+
+      it 'returns the number of commits between a branch and a sha' do
+        expect(repository.commits_between(branch, sha).count).to eq(0) # sha is before branch
+      end
+    end
+
+    context 'two branches' do
+      let(:first_branch) { 'feature' }
+      let(:second_branch) { 'master' }
+
+      it 'returns the number of commits between' do
+        expect(repository.commits_between(first_branch, second_branch).count).to eq(17)
+      end
+    end
+  end
+
+  describe '#count_commits_between' do
+    subject { repository.count_commits_between('feature', 'master') }
+
+    it { is_expected.to eq(17) }
+  end
+
+  describe "branch_names_contains" do
+    subject { repository.branch_names_contains(SeedRepo::LastCommit::ID) }
+
+    it { is_expected.to include('master') }
+    it { is_expected.not_to include('feature') }
+    it { is_expected.not_to include('fix') }
+  end
+
+  describe '#autocrlf' do
+    before(:all) do
+      @repo = Gitlab::Git::Repository.new(TEST_MUTABLE_REPO_PATH)
+      @repo.rugged.config['core.autocrlf'] = true
+    end
+
+    it 'return the value of the autocrlf option' do
+      expect(@repo.autocrlf).to be(true)
+    end
+
+    after(:all) do
+      @repo.rugged.config.delete('core.autocrlf')
+    end
+  end
+
+  describe '#autocrlf=' do
+    before(:all) do
+      @repo = Gitlab::Git::Repository.new(TEST_MUTABLE_REPO_PATH)
+      @repo.rugged.config['core.autocrlf'] = false
+    end
+
+    it 'should set the autocrlf option to the provided option' do
+      @repo.autocrlf = :input
+
+      File.open(File.join(TEST_MUTABLE_REPO_PATH, '.git', 'config')) do |config_file|
+        expect(config_file.read).to match('autocrlf = input')
+      end
+    end
+
+    after(:all) do
+      @repo.rugged.config.delete('core.autocrlf')
+    end
+  end
+
+  describe '#find_branch' do
+    it 'should return a Branch for master' do
+      branch = repository.find_branch('master')
+
+      expect(branch).to be_a_kind_of(Gitlab::Git::Branch)
+      expect(branch.name).to eq('master')
+    end
+
+    it 'should handle non-existent branch' do
+      branch = repository.find_branch('this-is-garbage')
+
+      expect(branch).to eq(nil)
+    end
+
+    it 'should reload Rugged::Repository and return master' do
+      expect(Rugged::Repository).to receive(:new).twice.and_call_original
+
+      repository.find_branch('master')
+      branch = repository.find_branch('master', force_reload: true)
+
+      expect(branch).to be_a_kind_of(Gitlab::Git::Branch)
+      expect(branch.name).to eq('master')
+    end
+  end
+
+  describe '#branches with deleted branch' do
+    before(:each) do
+      ref = double()
+      allow(ref).to receive(:name) { 'bad-branch' }
+      allow(ref).to receive(:target) { raise Rugged::ReferenceError }
+      allow(repository.rugged).to receive(:branches) { [ref] }
+    end
+
+    it 'should return empty branches' do
+      expect(repository.branches).to eq([])
+    end
+  end
+
+  describe '#branch_count' do
+    before(:each) do
+      valid_ref   = double(:ref)
+      invalid_ref = double(:ref)
+
+      allow(valid_ref).to receive_messages(name: 'master', target: double(:target))
+
+      allow(invalid_ref).to receive_messages(name: 'bad-branch')
+      allow(invalid_ref).to receive(:target) { raise Rugged::ReferenceError }
+
+      allow(repository.rugged).to receive_messages(branches: [valid_ref, invalid_ref])
+    end
+
+    it 'returns the number of branches' do
+      expect(repository.branch_count).to eq(1)
+    end
+  end
+
+  describe '#mkdir' do
+    let(:commit_options) do
+      {
+        author: {
+          email: 'user@example.com',
+          name: 'Test User',
+          time: Time.now
+        },
+        committer: {
+          email: 'user@example.com',
+          name: 'Test User',
+          time: Time.now
+        },
+        commit: {
+          message: 'Test message',
+          branch: 'refs/heads/fix',
+        }
+      }
+    end
+
+    def generate_diff_for_path(path)
+      "diff --git a/#{path}/.gitkeep b/#{path}/.gitkeep
+new file mode 100644
+index 0000000..e69de29
+--- /dev/null
++++ b/#{path}/.gitkeep\n"
+    end
+
+    shared_examples 'mkdir diff check' do |path, expected_path|
+      it 'creates a directory' do
+        result = repository.mkdir(path, commit_options)
+        expect(result).not_to eq(nil)
+
+        diff_text = repository.diff_text("#{result}~1", result)
+        expected = generate_diff_for_path(expected_path)
+        expect(diff_text).to eq(expected)
+
+        # Verify another mkdir doesn't create a directory that already exists
+        expect{ repository.mkdir(path, commit_options) }.to raise_error('Directory already exists')
+      end
+    end
+
+    describe 'creates a directory in root directory' do
+      it_should_behave_like 'mkdir diff check', 'new_dir', 'new_dir'
+    end
+
+    describe 'creates a directory in subdirectory' do
+      it_should_behave_like 'mkdir diff check', 'files/ruby/test', 'files/ruby/test'
+    end
+
+    describe 'creates a directory in subdirectory with a slash' do
+      it_should_behave_like 'mkdir diff check', '/files/ruby/test2', 'files/ruby/test2'
+    end
+
+    describe 'creates a directory in subdirectory with multiple slashes' do
+      it_should_behave_like 'mkdir diff check', '//files/ruby/test3', 'files/ruby/test3'
+    end
+
+    describe 'handles relative paths' do
+      it_should_behave_like 'mkdir diff check', 'files/ruby/../test_relative', 'files/test_relative'
+    end
+
+    describe 'creates nested directories' do
+      it_should_behave_like 'mkdir diff check', 'files/missing/test', 'files/missing/test'
+    end
+
+    it 'does not attempt to create a directory with invalid relative path' do
+      expect{ repository.mkdir('../files/missing/test', commit_options) }.to raise_error('Invalid path')
+    end
+
+    it 'does not attempt to overwrite a file' do
+      expect{ repository.mkdir('README.md', commit_options) }.to raise_error('Directory already exists as a file')
+    end
+
+    it 'does not attempt to overwrite a directory' do
+      expect{ repository.mkdir('files', commit_options) }.to raise_error('Directory already exists')
+    end
+  end
+
+  describe "#ls_files" do
+    let(:master_file_paths) { repository.ls_files("master") }
+    let(:not_existed_branch) { repository.ls_files("not_existed_branch") }
+
+    it "read every file paths of master branch" do
+      expect(master_file_paths.length).to equal(40)
+    end
+
+    it "reads full file paths of master branch" do
+      expect(master_file_paths).to include("files/html/500.html")
+    end
+
+    it "dose not read submodule directory and empty directory of master branch" do
+      expect(master_file_paths).not_to include("six")
+    end
+
+    it "does not include 'nil'" do
+      expect(master_file_paths).not_to include(nil)
+    end
+
+    it "returns empty array when not existed branch" do
+      expect(not_existed_branch.length).to equal(0)
+    end
+  end
+
+  describe "#copy_gitattributes" do
+    let(:attributes_path) { File.join(TEST_REPO_PATH, 'info/attributes') }
+
+    it "raises an error with invalid ref" do
+      expect { repository.copy_gitattributes("invalid") }.to raise_error(Gitlab::Git::Repository::InvalidRef)
+    end
+
+    context "with no .gitattrbutes" do
+      before(:each) do
+        repository.copy_gitattributes("master")
+      end
+
+      it "does not have an info/attributes" do
+        expect(File.exist?(attributes_path)).to be_falsey
+      end
+
+      after(:each) do
+        FileUtils.rm_rf(attributes_path)
+      end
+    end
+
+    context "with .gitattrbutes" do
+      before(:each) do
+        repository.copy_gitattributes("gitattributes")
+      end
+
+      it "has an info/attributes" do
+        expect(File.exist?(attributes_path)).to be_truthy
+      end
+
+      it "has the same content in info/attributes as .gitattributes" do
+        contents = File.open(attributes_path, "rb") { |f| f.read }
+        expect(contents).to eq("*.md binary\n")
+      end
+
+      after(:each) do
+        FileUtils.rm_rf(attributes_path)
+      end
+    end
+
+    context "with updated .gitattrbutes" do
+      before(:each) do
+        repository.copy_gitattributes("gitattributes")
+        repository.copy_gitattributes("gitattributes-updated")
+      end
+
+      it "has an info/attributes" do
+        expect(File.exist?(attributes_path)).to be_truthy
+      end
+
+      it "has the updated content in info/attributes" do
+        contents = File.read(attributes_path)
+        expect(contents).to eq("*.txt binary\n")
+      end
+
+      after(:each) do
+        FileUtils.rm_rf(attributes_path)
+      end
+    end
+
+    context "with no .gitattrbutes in HEAD but with previous info/attributes" do
+      before(:each) do
+        repository.copy_gitattributes("gitattributes")
+        repository.copy_gitattributes("master")
+      end
+
+      it "does not have an info/attributes" do
+        expect(File.exist?(attributes_path)).to be_falsey
+      end
+
+      after(:each) do
+        FileUtils.rm_rf(attributes_path)
+      end
+    end
+  end
+
+  describe '#diffable' do
+    info_dir_path = attributes_path = File.join(TEST_REPO_PATH, 'info')
+    attributes_path = File.join(info_dir_path, 'attributes')
+
+    before(:all) do
+      FileUtils.mkdir(info_dir_path) unless File.exist?(info_dir_path)
+      File.write(attributes_path, "*.md -diff\n")
+    end
+
+    it "should return true for files which are text and do not have attributes" do
+      blob = Gitlab::Git::Blob.find(
+        repository,
+        '33bcff41c232a11727ac6d660bd4b0c2ba86d63d',
+        'LICENSE'
+      )
+      expect(repository.diffable?(blob)).to be_truthy
+    end
+
+    it "should return false for binary files which do not have attributes" do
+      blob = Gitlab::Git::Blob.find(
+        repository,
+        '33bcff41c232a11727ac6d660bd4b0c2ba86d63d',
+        'files/images/logo-white.png'
+      )
+      expect(repository.diffable?(blob)).to be_falsey
+    end
+
+    it "should return false for text files which have been marked as not being diffable in attributes" do
+      blob = Gitlab::Git::Blob.find(
+        repository,
+        '33bcff41c232a11727ac6d660bd4b0c2ba86d63d',
+        'README.md'
+      )
+      expect(repository.diffable?(blob)).to be_falsey
+    end
+
+    after(:all) do
+      FileUtils.rm_rf(info_dir_path)
+    end
+  end
+
+  describe '#tag_exists?' do
+    it 'returns true for an existing tag' do
+      tag = repository.tag_names.first
+
+      expect(repository.tag_exists?(tag)).to eq(true)
+    end
+
+    it 'returns false for a non-existing tag' do
+      expect(repository.tag_exists?('v9000')).to eq(false)
+    end
+  end
+
+  describe '#branch_exists?' do
+    it 'returns true for an existing branch' do
+      expect(repository.branch_exists?('master')).to eq(true)
+    end
+
+    it 'returns false for a non-existing branch' do
+      expect(repository.branch_exists?('kittens')).to eq(false)
+    end
+
+    it 'returns false when using an invalid branch name' do
+      expect(repository.branch_exists?('.bla')).to eq(false)
+    end
+  end
+
+  describe '#local_branches' do
+    before(:all) do
+      @repo = Gitlab::Git::Repository.new(TEST_MUTABLE_REPO_PATH)
+    end
+
+    after(:all) do
+      FileUtils.rm_rf(TEST_MUTABLE_REPO_PATH)
+      ensure_seeds
+    end
+
+    it 'returns the local branches' do
+      create_remote_branch('joe', 'remote_branch', 'master')
+      @repo.create_branch('local_branch', 'master')
+
+      expect(@repo.local_branches.any? { |branch| branch.name == 'remote_branch' }).to eq(false)
+      expect(@repo.local_branches.any? { |branch| branch.name == 'local_branch' }).to eq(true)
+    end
+  end
+
+  def create_remote_branch(remote_name, branch_name, source_branch_name)
+    source_branch = @repo.branches.find { |branch| branch.name == source_branch_name }
+    rugged = @repo.rugged
+    rugged.references.create("refs/remotes/#{remote_name}/#{branch_name}", source_branch.dereferenced_target.sha)
+  end
+end
diff --git a/spec/lib/gitlab/git/tag_spec.rb b/spec/lib/gitlab/git/tag_spec.rb
new file mode 100644
index 00000000000..b09a567392b
--- /dev/null
+++ b/spec/lib/gitlab/git/tag_spec.rb
@@ -0,0 +1,25 @@
+require "gitlab_git_spec_helper"
+
+describe Gitlab::Git::Tag do
+  let(:repository) { Gitlab::Git::Repository.new(TEST_REPO_PATH) }
+
+  describe 'first tag' do
+    let(:tag) { repository.tags.first }
+
+    it { expect(tag.name).to eq("v1.0.0") }
+    it { expect(tag.target).to eq("f4e6814c3e4e7a0de82a9e7cd20c626cc963a2f8") }
+    it { expect(tag.dereferenced_target.sha).to eq("6f6d7e7ed97bb5f0054f2b1df789b39ca89b6ff9") }
+    it { expect(tag.message).to eq("Release") }
+  end
+
+  describe 'last tag' do
+    let(:tag) { repository.tags.last }
+
+    it { expect(tag.name).to eq("v1.2.1") }
+    it { expect(tag.target).to eq("2ac1f24e253e08135507d0830508febaaccf02ee") }
+    it { expect(tag.dereferenced_target.sha).to eq("fa1b1e6c004a68b7d8763b86455da9e6b23e36d6") }
+    it { expect(tag.message).to eq("Version 1.2.1") }
+  end
+
+  it { expect(repository.tags.size).to eq(SeedRepo::Repo::TAGS.size) }
+end
diff --git a/spec/lib/gitlab/git/tree_spec.rb b/spec/lib/gitlab/git/tree_spec.rb
new file mode 100644
index 00000000000..1af533f611e
--- /dev/null
+++ b/spec/lib/gitlab/git/tree_spec.rb
@@ -0,0 +1,76 @@
+require "gitlab_git_spec_helper"
+
+describe Gitlab::Git::Tree do
+  context :repo do
+    let(:repository) { Gitlab::Git::Repository.new(TEST_REPO_PATH) }
+    let(:tree) { Gitlab::Git::Tree.where(repository, SeedRepo::Commit::ID) }
+
+    it { expect(tree).to be_kind_of Array }
+    it { expect(tree.empty?).to be_falsey }
+    it { expect(tree.select(&:dir?).size).to eq(2) }
+    it { expect(tree.select(&:file?).size).to eq(10) }
+    it { expect(tree.select(&:submodule?).size).to eq(2) }
+
+    describe :dir do
+      let(:dir) { tree.select(&:dir?).first }
+
+      it { expect(dir).to be_kind_of Gitlab::Git::Tree }
+      it { expect(dir.id).to eq('3c122d2b7830eca25235131070602575cf8b41a1') }
+      it { expect(dir.commit_id).to eq(SeedRepo::Commit::ID) }
+      it { expect(dir.name).to eq('encoding') }
+      it { expect(dir.path).to eq('encoding') }
+
+      context :subdir do
+        let(:subdir) { Gitlab::Git::Tree.where(repository, SeedRepo::Commit::ID, 'files').first }
+
+        it { expect(subdir).to be_kind_of Gitlab::Git::Tree }
+        it { expect(subdir.id).to eq('a1e8f8d745cc87e3a9248358d9352bb7f9a0aeba') }
+        it { expect(subdir.commit_id).to eq(SeedRepo::Commit::ID) }
+        it { expect(subdir.name).to eq('html') }
+        it { expect(subdir.path).to eq('files/html') }
+      end
+
+      context :subdir_file do
+        let(:subdir_file) { Gitlab::Git::Tree.where(repository, SeedRepo::Commit::ID, 'files/ruby').first }
+
+        it { expect(subdir_file).to be_kind_of Gitlab::Git::Tree }
+        it { expect(subdir_file.id).to eq('7e3e39ebb9b2bf433b4ad17313770fbe4051649c') }
+        it { expect(subdir_file.commit_id).to eq(SeedRepo::Commit::ID) }
+        it { expect(subdir_file.name).to eq('popen.rb') }
+        it { expect(subdir_file.path).to eq('files/ruby/popen.rb') }
+      end
+    end
+
+    describe :file do
+      let(:file) { tree.select(&:file?).first }
+
+      it { expect(file).to be_kind_of Gitlab::Git::Tree }
+      it { expect(file.id).to eq('dfaa3f97ca337e20154a98ac9d0be76ddd1fcc82') }
+      it { expect(file.commit_id).to eq(SeedRepo::Commit::ID) }
+      it { expect(file.name).to eq('.gitignore') }
+    end
+
+    describe :readme do
+      let(:file) { tree.select(&:readme?).first }
+
+      it { expect(file).to be_kind_of Gitlab::Git::Tree }
+      it { expect(file.name).to eq('README.md') }
+    end
+
+    describe :contributing do
+      let(:file) { tree.select(&:contributing?).first }
+
+      it { expect(file).to be_kind_of Gitlab::Git::Tree }
+      it { expect(file.name).to eq('CONTRIBUTING.md') }
+    end
+
+    describe :submodule do
+      let(:submodule) { tree.select(&:submodule?).first }
+
+      it { expect(submodule).to be_kind_of Gitlab::Git::Tree }
+      it { expect(submodule.id).to eq('79bceae69cb5750d6567b223597999bfa91cb3b9') }
+      it { expect(submodule.commit_id).to eq('570e7b2abdd848b95f2f578043fc23bd6f6fd24d') }
+      it { expect(submodule.name).to eq('gitlab-shell') }
+    end
+  end
+end
diff --git a/spec/lib/gitlab/git/util_spec.rb b/spec/lib/gitlab/git/util_spec.rb
new file mode 100644
index 00000000000..455884cc79f
--- /dev/null
+++ b/spec/lib/gitlab/git/util_spec.rb
@@ -0,0 +1,16 @@
+require "gitlab_git_spec_helper"
+
+describe Gitlab::Git::Util do
+  describe :count_lines do
+    [
+      ["", 0],
+      ["foo", 1],
+      ["foo\n", 1],
+      ["foo\n\n", 2],
+    ].each do |string, line_count|
+      it "counts #{line_count} lines in #{string.inspect}" do
+        expect(Gitlab::Git::Util.count_lines(string)).to eq(line_count)
+      end
+    end
+  end
+end
diff --git a/spec/support/gitlab_git/big_commit.rb b/spec/support/gitlab_git/big_commit.rb
new file mode 100644
index 00000000000..b0ffd8f71be
--- /dev/null
+++ b/spec/support/gitlab_git/big_commit.rb
@@ -0,0 +1,34 @@
+# Seed repo:
+# 0e50ec4d3c7ce42ab74dda1d422cb2cbffe1e326 Merge branch 'lfs_pointers' into 'master'
+# 33bcff41c232a11727ac6d660bd4b0c2ba86d63d Add valid and invalid lfs pointers
+# 732401c65e924df81435deb12891ef570167d2e2 Update year in license file
+# b0e52af38d7ea43cf41d8a6f2471351ac036d6c9 Empty commit
+# 40f4a7a617393735a95a0bb67b08385bc1e7c66d Add ISO-8859-encoded file
+# 66028349a123e695b589e09a36634d976edcc5e8 Merge branch 'add-comments-to-gitmodules' into 'master'
+# de5714f34c4e34f1d50b9a61a2e6c9132fe2b5fd Add comments to the end of .gitmodules to test parsing
+# fa1b1e6c004a68b7d8763b86455da9e6b23e36d6 Merge branch 'add-files' into 'master'
+# eb49186cfa5c4338011f5f590fac11bd66c5c631 Add submodules nested deeper than the root
+# 18d9c205d0d22fdf62bc2f899443b83aafbf941f Add executables and links files
+# 5937ac0a7beb003549fc5fd26fc247adbce4a52e Add submodule from gitlab.com
+# 570e7b2abdd848b95f2f578043fc23bd6f6fd24d Change some files
+# 6f6d7e7ed97bb5f0054f2b1df789b39ca89b6ff9 More submodules
+# d14d6c0abdd253381df51a723d58691b2ee1ab08 Remove ds_store files
+# c1acaa58bbcbc3eafe538cb8274ba387047b69f8 Ignore DS files
+# ae73cb07c9eeaf35924a10f713b364d32b2dd34f Binary file added
+# 874797c3a73b60d2187ed6e2fcabd289ff75171e Ruby files modified
+# 2f63565e7aac07bcdadb654e253078b727143ec4 Modified image
+# 33f3729a45c02fc67d00adb1b8bca394b0e761d9 Image added
+# 913c66a37b4a45b9769037c55c2d238bd0942d2e Files, encoding and much more
+# cfe32cf61b73a0d5e9f13e774abde7ff789b1660 Add submodule
+# 6d394385cf567f80a8fd85055db1ab4c5295806f Added contributing guide
+# 1a0b36b3cdad1d2ee32457c102a8c0b7056fa863 Initial commit
+#
+module SeedRepo
+  module BigCommit
+    ID = "913c66a37b4a45b9769037c55c2d238bd0942d2e"
+    PARENT_ID = "cfe32cf61b73a0d5e9f13e774abde7ff789b1660"
+    MESSAGE = "Files, encoding and much more"
+    AUTHOR_FULL_NAME = "Dmitriy Zaporozhets"
+    FILES_COUNT = 2
+  end
+end
diff --git a/spec/support/gitlab_git/commit.rb b/spec/support/gitlab_git/commit.rb
new file mode 100644
index 00000000000..820e837f21b
--- /dev/null
+++ b/spec/support/gitlab_git/commit.rb
@@ -0,0 +1,42 @@
+# Seed repo:
+# 0e50ec4d3c7ce42ab74dda1d422cb2cbffe1e326 Merge branch 'lfs_pointers' into 'master'
+# 33bcff41c232a11727ac6d660bd4b0c2ba86d63d Add valid and invalid lfs pointers
+# 732401c65e924df81435deb12891ef570167d2e2 Update year in license file
+# b0e52af38d7ea43cf41d8a6f2471351ac036d6c9 Empty commit
+# 40f4a7a617393735a95a0bb67b08385bc1e7c66d Add ISO-8859-encoded file
+# 66028349a123e695b589e09a36634d976edcc5e8 Merge branch 'add-comments-to-gitmodules' into 'master'
+# de5714f34c4e34f1d50b9a61a2e6c9132fe2b5fd Add comments to the end of .gitmodules to test parsing
+# fa1b1e6c004a68b7d8763b86455da9e6b23e36d6 Merge branch 'add-files' into 'master'
+# eb49186cfa5c4338011f5f590fac11bd66c5c631 Add submodules nested deeper than the root
+# 18d9c205d0d22fdf62bc2f899443b83aafbf941f Add executables and links files
+# 5937ac0a7beb003549fc5fd26fc247adbce4a52e Add submodule from gitlab.com
+# 570e7b2abdd848b95f2f578043fc23bd6f6fd24d Change some files
+# 6f6d7e7ed97bb5f0054f2b1df789b39ca89b6ff9 More submodules
+# d14d6c0abdd253381df51a723d58691b2ee1ab08 Remove ds_store files
+# c1acaa58bbcbc3eafe538cb8274ba387047b69f8 Ignore DS files
+# ae73cb07c9eeaf35924a10f713b364d32b2dd34f Binary file added
+# 874797c3a73b60d2187ed6e2fcabd289ff75171e Ruby files modified
+# 2f63565e7aac07bcdadb654e253078b727143ec4 Modified image
+# 33f3729a45c02fc67d00adb1b8bca394b0e761d9 Image added
+# 913c66a37b4a45b9769037c55c2d238bd0942d2e Files, encoding and much more
+# cfe32cf61b73a0d5e9f13e774abde7ff789b1660 Add submodule
+# 6d394385cf567f80a8fd85055db1ab4c5295806f Added contributing guide
+# 1a0b36b3cdad1d2ee32457c102a8c0b7056fa863 Initial commit
+#
+module SeedRepo
+  module Commit
+    ID = "570e7b2abdd848b95f2f578043fc23bd6f6fd24d"
+    PARENT_ID = "6f6d7e7ed97bb5f0054f2b1df789b39ca89b6ff9"
+    MESSAGE = "Change some files\n\nSigned-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>\n"
+    AUTHOR_FULL_NAME = "Dmitriy Zaporozhets"
+
+    FILES = ["files/ruby/popen.rb", "files/ruby/regex.rb"]
+    FILES_COUNT = 2
+
+    C_FILE_PATH = "files/ruby"
+    C_FILES = ["popen.rb", "regex.rb", "version_info.rb"]
+
+    BLOB_FILE = %{%h3= @key.title\n%hr\n%pre= @key.key\n.actions\n  = link_to 'Remove', @key, :confirm => 'Are you sure?', :method => :delete, :class => \"btn danger delete-key\"\n\n\n}
+    BLOB_FILE_PATH = "app/views/keys/show.html.haml"
+  end
+end
diff --git a/spec/support/gitlab_git/empty_commit.rb b/spec/support/gitlab_git/empty_commit.rb
new file mode 100644
index 00000000000..61664740492
--- /dev/null
+++ b/spec/support/gitlab_git/empty_commit.rb
@@ -0,0 +1,33 @@
+# Seed repo:
+# 732401c65e924df81435deb12891ef570167d2e2 Update year in license file
+# b0e52af38d7ea43cf41d8a6f2471351ac036d6c9 Empty commit
+# 40f4a7a617393735a95a0bb67b08385bc1e7c66d Add ISO-8859-encoded file
+# 66028349a123e695b589e09a36634d976edcc5e8 Merge branch 'add-comments-to-gitmodules' into 'master'
+# de5714f34c4e34f1d50b9a61a2e6c9132fe2b5fd Add comments to the end of .gitmodules to test parsing
+# fa1b1e6c004a68b7d8763b86455da9e6b23e36d6 Merge branch 'add-files' into 'master'
+# eb49186cfa5c4338011f5f590fac11bd66c5c631 Add submodules nested deeper than the root
+# 18d9c205d0d22fdf62bc2f899443b83aafbf941f Add executables and links files
+# 5937ac0a7beb003549fc5fd26fc247adbce4a52e Add submodule from gitlab.com
+# 570e7b2abdd848b95f2f578043fc23bd6f6fd24d Change some files
+# 6f6d7e7ed97bb5f0054f2b1df789b39ca89b6ff9 More submodules
+# d14d6c0abdd253381df51a723d58691b2ee1ab08 Remove ds_store files
+# c1acaa58bbcbc3eafe538cb8274ba387047b69f8 Ignore DS files
+# ae73cb07c9eeaf35924a10f713b364d32b2dd34f Binary file added
+# 874797c3a73b60d2187ed6e2fcabd289ff75171e Ruby files modified
+# 2f63565e7aac07bcdadb654e253078b727143ec4 Modified image
+# 33f3729a45c02fc67d00adb1b8bca394b0e761d9 Image added
+# 913c66a37b4a45b9769037c55c2d238bd0942d2e Files, encoding and much more
+# cfe32cf61b73a0d5e9f13e774abde7ff789b1660 Add submodule
+# 6d394385cf567f80a8fd85055db1ab4c5295806f Added contributing guide
+# 1a0b36b3cdad1d2ee32457c102a8c0b7056fa863 Initial commit
+#
+module SeedRepo
+  module EmptyCommit
+    ID = "b0e52af38d7ea43cf41d8a6f2471351ac036d6c9"
+    PARENT_ID = "40f4a7a617393735a95a0bb67b08385bc1e7c66d"
+    MESSAGE = "Empty commit"
+    AUTHOR_FULL_NAME = "Rémy Coutable"
+    FILES = []
+    FILES_COUNT = FILES.count
+  end
+end
diff --git a/spec/support/gitlab_git/encoding_commit.rb b/spec/support/gitlab_git/encoding_commit.rb
new file mode 100644
index 00000000000..75688eb662b
--- /dev/null
+++ b/spec/support/gitlab_git/encoding_commit.rb
@@ -0,0 +1,33 @@
+# Seed repo:
+# 732401c65e924df81435deb12891ef570167d2e2 Update year in license file
+# b0e52af38d7ea43cf41d8a6f2471351ac036d6c9 Empty commit
+# 40f4a7a617393735a95a0bb67b08385bc1e7c66d Add ISO-8859-encoded file
+# 66028349a123e695b589e09a36634d976edcc5e8 Merge branch 'add-comments-to-gitmodules' into 'master'
+# de5714f34c4e34f1d50b9a61a2e6c9132fe2b5fd Add comments to the end of .gitmodules to test parsing
+# fa1b1e6c004a68b7d8763b86455da9e6b23e36d6 Merge branch 'add-files' into 'master'
+# eb49186cfa5c4338011f5f590fac11bd66c5c631 Add submodules nested deeper than the root
+# 18d9c205d0d22fdf62bc2f899443b83aafbf941f Add executables and links files
+# 5937ac0a7beb003549fc5fd26fc247adbce4a52e Add submodule from gitlab.com
+# 570e7b2abdd848b95f2f578043fc23bd6f6fd24d Change some files
+# 6f6d7e7ed97bb5f0054f2b1df789b39ca89b6ff9 More submodules
+# d14d6c0abdd253381df51a723d58691b2ee1ab08 Remove ds_store files
+# c1acaa58bbcbc3eafe538cb8274ba387047b69f8 Ignore DS files
+# ae73cb07c9eeaf35924a10f713b364d32b2dd34f Binary file added
+# 874797c3a73b60d2187ed6e2fcabd289ff75171e Ruby files modified
+# 2f63565e7aac07bcdadb654e253078b727143ec4 Modified image
+# 33f3729a45c02fc67d00adb1b8bca394b0e761d9 Image added
+# 913c66a37b4a45b9769037c55c2d238bd0942d2e Files, encoding and much more
+# cfe32cf61b73a0d5e9f13e774abde7ff789b1660 Add submodule
+# 6d394385cf567f80a8fd85055db1ab4c5295806f Added contributing guide
+# 1a0b36b3cdad1d2ee32457c102a8c0b7056fa863 Initial commit
+#
+module SeedRepo
+  module EncodingCommit
+    ID = "40f4a7a617393735a95a0bb67b08385bc1e7c66d"
+    PARENT_ID = "66028349a123e695b589e09a36634d976edcc5e8"
+    MESSAGE = "Add ISO-8859-encoded file"
+    AUTHOR_FULL_NAME = "Stan Hu"
+    FILES = ["encoding/iso8859.txt"]
+    FILES_COUNT = FILES.count
+  end
+end
diff --git a/spec/support/gitlab_git/first_commit.rb b/spec/support/gitlab_git/first_commit.rb
new file mode 100644
index 00000000000..a01f93290e9
--- /dev/null
+++ b/spec/support/gitlab_git/first_commit.rb
@@ -0,0 +1,35 @@
+# Seed repo:
+# 0e50ec4d3c7ce42ab74dda1d422cb2cbffe1e326 Merge branch 'lfs_pointers' into 'master'
+# 33bcff41c232a11727ac6d660bd4b0c2ba86d63d Add valid and invalid lfs pointers
+# 732401c65e924df81435deb12891ef570167d2e2 Update year in license file
+# b0e52af38d7ea43cf41d8a6f2471351ac036d6c9 Empty commit
+# 40f4a7a617393735a95a0bb67b08385bc1e7c66d Add ISO-8859-encoded file
+# 66028349a123e695b589e09a36634d976edcc5e8 Merge branch 'add-comments-to-gitmodules' into 'master'
+# de5714f34c4e34f1d50b9a61a2e6c9132fe2b5fd Add comments to the end of .gitmodules to test parsing
+# fa1b1e6c004a68b7d8763b86455da9e6b23e36d6 Merge branch 'add-files' into 'master'
+# eb49186cfa5c4338011f5f590fac11bd66c5c631 Add submodules nested deeper than the root
+# 18d9c205d0d22fdf62bc2f899443b83aafbf941f Add executables and links files
+# 5937ac0a7beb003549fc5fd26fc247adbce4a52e Add submodule from gitlab.com
+# 570e7b2abdd848b95f2f578043fc23bd6f6fd24d Change some files
+# 6f6d7e7ed97bb5f0054f2b1df789b39ca89b6ff9 More submodules
+# d14d6c0abdd253381df51a723d58691b2ee1ab08 Remove ds_store files
+# c1acaa58bbcbc3eafe538cb8274ba387047b69f8 Ignore DS files
+# ae73cb07c9eeaf35924a10f713b364d32b2dd34f Binary file added
+# 874797c3a73b60d2187ed6e2fcabd289ff75171e Ruby files modified
+# 2f63565e7aac07bcdadb654e253078b727143ec4 Modified image
+# 33f3729a45c02fc67d00adb1b8bca394b0e761d9 Image added
+# 913c66a37b4a45b9769037c55c2d238bd0942d2e Files, encoding and much more
+# cfe32cf61b73a0d5e9f13e774abde7ff789b1660 Add submodule
+# 6d394385cf567f80a8fd85055db1ab4c5295806f Added contributing guide
+# 1a0b36b3cdad1d2ee32457c102a8c0b7056fa863 Initial commit
+#
+module SeedRepo
+  module FirstCommit
+    ID = "1a0b36b3cdad1d2ee32457c102a8c0b7056fa863"
+    PARENT_ID = nil
+    MESSAGE = "Initial commit"
+    AUTHOR_FULL_NAME = "Dmitriy Zaporozhets"
+    FILES = ["LICENSE", ".gitignore", "README.md"]
+    FILES_COUNT = 3
+  end
+end
diff --git a/spec/support/gitlab_git/gitlab_logo.png b/spec/support/gitlab_git/gitlab_logo.png
new file mode 100644
index 00000000000..4b455657c0a
--- /dev/null
+++ b/spec/support/gitlab_git/gitlab_logo.png
diff --git a/spec/support/gitlab_git/last_commit.rb b/spec/support/gitlab_git/last_commit.rb
new file mode 100644
index 00000000000..c1a1daef920
--- /dev/null
+++ b/spec/support/gitlab_git/last_commit.rb
@@ -0,0 +1,37 @@
+# Seed repo:
+# 4b4918a572fa86f9771e5ba40fbd48e1eb03e2c6 Merge branch 'master' into 'master'
+# 0e1b353b348f8477bdbec1ef47087171c5032cd9 adds an executable with different permissions
+# 0e50ec4d3c7ce42ab74dda1d422cb2cbffe1e326 Merge branch 'lfs_pointers' into 'master'
+# 33bcff41c232a11727ac6d660bd4b0c2ba86d63d Add valid and invalid lfs pointers
+# 732401c65e924df81435deb12891ef570167d2e2 Update year in license file
+# b0e52af38d7ea43cf41d8a6f2471351ac036d6c9 Empty commit
+# 40f4a7a617393735a95a0bb67b08385bc1e7c66d Add ISO-8859-encoded file
+# 66028349a123e695b589e09a36634d976edcc5e8 Merge branch 'add-comments-to-gitmodules' into 'master'
+# de5714f34c4e34f1d50b9a61a2e6c9132fe2b5fd Add comments to the end of .gitmodules to test parsing
+# fa1b1e6c004a68b7d8763b86455da9e6b23e36d6 Merge branch 'add-files' into 'master'
+# eb49186cfa5c4338011f5f590fac11bd66c5c631 Add submodules nested deeper than the root
+# 18d9c205d0d22fdf62bc2f899443b83aafbf941f Add executables and links files
+# 5937ac0a7beb003549fc5fd26fc247adbce4a52e Add submodule from gitlab.com
+# 570e7b2abdd848b95f2f578043fc23bd6f6fd24d Change some files
+# 6f6d7e7ed97bb5f0054f2b1df789b39ca89b6ff9 More submodules
+# d14d6c0abdd253381df51a723d58691b2ee1ab08 Remove ds_store files
+# c1acaa58bbcbc3eafe538cb8274ba387047b69f8 Ignore DS files
+# ae73cb07c9eeaf35924a10f713b364d32b2dd34f Binary file added
+# 874797c3a73b60d2187ed6e2fcabd289ff75171e Ruby files modified
+# 2f63565e7aac07bcdadb654e253078b727143ec4 Modified image
+# 33f3729a45c02fc67d00adb1b8bca394b0e761d9 Image added
+# 913c66a37b4a45b9769037c55c2d238bd0942d2e Files, encoding and much more
+# cfe32cf61b73a0d5e9f13e774abde7ff789b1660 Add submodule
+# 6d394385cf567f80a8fd85055db1ab4c5295806f Added contributing guide
+# 1a0b36b3cdad1d2ee32457c102a8c0b7056fa863 Initial commit
+#
+module SeedRepo
+  module LastCommit
+    ID = "4b4918a572fa86f9771e5ba40fbd48e1eb03e2c6"
+    PARENT_ID = "0e1b353b348f8477bdbec1ef47087171c5032cd9"
+    MESSAGE = "Merge branch 'master' into 'master'"
+    AUTHOR_FULL_NAME = "Stan Hu"
+    FILES = ["bin/executable"]
+    FILES_COUNT = FILES.count
+  end
+end
diff --git a/spec/support/gitlab_git/repo.rb b/spec/support/gitlab_git/repo.rb
new file mode 100644
index 00000000000..dc55f1ffd9d
--- /dev/null
+++ b/spec/support/gitlab_git/repo.rb
@@ -0,0 +1,80 @@
+module SeedRepo
+  module Repo
+    HEAD = "master"
+    BRANCHES = %w(
+      feature fix fix-blob-path fix-existing-submodule-dir fix-mode gitattributes
+      gitattributes-updated master merge-test
+    )
+    TAGS = %w(v1.0.0 v1.1.0 v1.2.0 v1.2.1)
+  end
+end
+
+# Writes a new commit to the repo and returns a Rugged::Commit.  Replaces the
+# contents of CHANGELOG with a single new line of text.
+def new_commit_edit_old_file(repo)
+  oid = repo.write("I replaced the changelog with this text", :blob)
+  index = repo.index
+  index.read_tree(repo.head.target.tree)
+  index.add(path: "CHANGELOG", oid: oid, mode: 0100644)
+
+  options = commit_options(
+    repo,
+    index,
+    "Edit CHANGELOG in its original location"
+  )
+
+  sha = Rugged::Commit.create(repo, options)
+  repo.lookup(sha)
+end
+
+# Writes a new commit to the repo and returns a Rugged::Commit.  Moves the
+# CHANGELOG file to the encoding/ directory.
+def new_commit_move_file(repo)
+  blob_oid = repo.head.target.tree.detect { |i| i[:name] == "CHANGELOG" }[:oid]
+  file_content = repo.lookup(blob_oid).content
+  oid = repo.write(file_content, :blob)
+  index = repo.index
+  index.read_tree(repo.head.target.tree)
+  index.add(path: "encoding/CHANGELOG", oid: oid, mode: 0100644)
+  index.remove("CHANGELOG")
+
+  options = commit_options(repo, index, "Move CHANGELOG to encoding/")
+
+  sha = Rugged::Commit.create(repo, options)
+  repo.lookup(sha)
+end
+
+# Writes a new commit to the repo and returns a Rugged::Commit.  Replaces the
+# contents of encoding/CHANGELOG with new text.
+def new_commit_edit_new_file(repo)
+  oid = repo.write("I'm a new changelog with different text", :blob)
+  index = repo.index
+  index.read_tree(repo.head.target.tree)
+  index.add(path: "encoding/CHANGELOG", oid: oid, mode: 0100644)
+
+  options = commit_options(repo, index, "Edit encoding/CHANGELOG")
+
+  sha = Rugged::Commit.create(repo, options)
+  repo.lookup(sha)
+end
+
+# Build the options hash that's passed to Rugged::Commit#create
+def commit_options(repo, index, message)
+  options = {}
+  options[:tree] = index.write_tree(repo)
+  options[:author] = {
+    email: "test@example.com",
+    name: "Test Author",
+    time: Time.gm(2014, "mar", 3, 20, 15, 1)
+  }
+  options[:committer] = {
+    email: "test@example.com",
+    name: "Test Author",
+    time: Time.gm(2014, "mar", 3, 20, 15, 1)
+  }
+  options[:message] ||= message
+  options[:parents] = repo.empty? ? [] : [repo.head.target].compact
+  options[:update_ref] = "HEAD"
+
+  options
+end
diff --git a/spec/support/gitlab_git/ruby_blob.rb b/spec/support/gitlab_git/ruby_blob.rb
new file mode 100644
index 00000000000..d3124583b6d
--- /dev/null
+++ b/spec/support/gitlab_git/ruby_blob.rb
@@ -0,0 +1,48 @@
+#
+# From SeedRepo::Commit::ID
+#
+module SeedRepo
+  module RubyBlob
+    ID = "7e3e39ebb9b2bf433b4ad17313770fbe4051649c"
+    NAME = "popen.rb"
+    CONTENT = <<-eos
+require 'fileutils'
+require 'open3'
+
+module Popen
+  extend self
+
+  def popen(cmd, path=nil)
+    unless cmd.is_a?(Array)
+      raise RuntimeError, "System commands must be given as an array of strings"
+    end
+
+    path ||= Dir.pwd
+
+    vars = {
+      "PWD" => path
+    }
+
+    options = {
+      chdir: path
+    }
+
+    unless File.directory?(path)
+      FileUtils.mkdir_p(path)
+    end
+
+    @cmd_output = ""
+    @cmd_status = 0
+
+    Open3.popen3(vars, *cmd, options) do |stdin, stdout, stderr, wait_thr|
+      @cmd_output << stdout.read
+      @cmd_output << stderr.read
+      @cmd_status = wait_thr.value.exitstatus
+    end
+
+    return @cmd_output, @cmd_status
+  end
+end
+    eos
+  end
+end
diff --git a/spec/support/gitlab_git/seed_helper.rb b/spec/support/gitlab_git/seed_helper.rb
new file mode 100644
index 00000000000..a7b1bd355c2
--- /dev/null
+++ b/spec/support/gitlab_git/seed_helper.rb
@@ -0,0 +1,96 @@
+module SeedHelper
+  GITLAB_URL = "https://gitlab.com/gitlab-org/gitlab-git-test.git"
+
+  def ensure_seeds
+    if File.exist?(GITLAB_GIT_REPOS_PATH)
+      FileUtils.rm_r(GITLAB_GIT_REPOS_PATH)
+    end
+
+    FileUtils.mkdir_p(GITLAB_GIT_REPOS_PATH)
+
+    create_bare_seeds
+    create_normal_seeds
+    create_mutable_seeds
+    create_broken_seeds
+    create_git_attributes
+    create_invalid_git_attributes
+  end
+
+  def create_bare_seeds
+    system(git_env, *%W(git clone --bare #{GITLAB_URL}),
+           chdir: GITLAB_GIT_REPOS_PATH,
+           out:   '/dev/null',
+           err:   '/dev/null')
+  end
+
+  def create_normal_seeds
+    system(git_env, *%W(git clone #{TEST_REPO_PATH} #{TEST_NORMAL_REPO_PATH}),
+           out: '/dev/null',
+           err: '/dev/null')
+  end
+
+  def create_mutable_seeds
+    system(git_env, *%W(git clone #{TEST_REPO_PATH} #{TEST_MUTABLE_REPO_PATH}),
+           out: '/dev/null',
+           err: '/dev/null')
+
+    system(git_env, *%w(git branch -t feature origin/feature),
+           chdir: TEST_MUTABLE_REPO_PATH, out: '/dev/null', err: '/dev/null')
+
+    system(git_env, *%W(git remote add expendable #{GITLAB_URL}),
+           chdir: TEST_MUTABLE_REPO_PATH, out: '/dev/null', err: '/dev/null')
+  end
+
+  def create_broken_seeds
+    system(git_env, *%W(git clone --bare #{TEST_REPO_PATH} #{TEST_BROKEN_REPO_PATH}),
+           out: '/dev/null',
+           err: '/dev/null')
+
+    refs_path = File.join(TEST_BROKEN_REPO_PATH, 'refs')
+
+    FileUtils.rm_r(refs_path)
+  end
+
+  def create_git_attributes
+    dir = File.join(GITLAB_GIT_REPOS_PATH, 'with-git-attributes.git', 'info')
+
+    FileUtils.mkdir_p(dir)
+
+    File.open(File.join(dir, 'attributes'), 'w') do |handle|
+      handle.write <<-EOF.strip
+# This is a comment, it should be ignored.
+
+*.txt     text
+*.jpg     -text
+*.sh      eol=lf gitlab-language=shell
+*.haml.*  gitlab-language=haml
+foo/bar.* foo
+*.cgi     key=value?p1=v1&p2=v2
+/*.png    gitlab-language=png
+*.binary  binary
+
+# This uses a tab instead of spaces to ensure the parser also supports this.
+*.md\tgitlab-language=markdown
+bla/bla.txt
+      EOF
+    end
+  end
+
+  def create_invalid_git_attributes
+    dir = File.join(GITLAB_GIT_REPOS_PATH, 'with-invalid-git-attributes.git', 'info')
+
+    FileUtils.mkdir_p(dir)
+
+    enc = Encoding::UTF_16
+
+    File.open(File.join(dir, 'attributes'), 'w', encoding: enc) do |handle|
+      handle.write('# hello'.encode(enc))
+    end
+  end
+
+  # Prevent developer git configurations from being persisted to test
+  # repositories
+  def git_env
+    { 'GIT_TEMPLATE_DIR' => '' }
+  end
+end