1 files changed, 60 insertions, 0 deletions
diff --git a/spec/support/bare_repo_operations.rb b/spec/support/bare_repo_operations.rb
new file mode 100644
index 00000000000..38d11992dc2
--- /dev/null
+++ b/spec/support/bare_repo_operations.rb
@@ -0,0 +1,60 @@
+require 'zlib'
+
+class BareRepoOperations
+  # The ID of empty tree.
+  # See http://stackoverflow.com/a/40884093/1856239 and https://github.com/git/git/blob/3ad8b5bf26362ac67c9020bf8c30eee54a84f56d/cache.h#L1011-L1012
+  EMPTY_TREE_ID = '4b825dc642cb6eb9a060e54bf8d69288fbee4904'.freeze
+
+  include Gitlab::Popen
+
+  def initialize(path_to_repo)
+    @path_to_repo = path_to_repo
+  end
+
+  # Based on https://stackoverflow.com/a/25556917/1856239
+  def commit_file(file, dst_path, branch = 'master')
+    head_id = execute(['show', '--format=format:%H', '--no-patch', branch], allow_failure: true)[0] || EMPTY_TREE_ID
+
+    execute(['read-tree', '--empty'])
+    execute(['read-tree', head_id])
+
+    blob_id = execute(['hash-object', '--stdin', '-w']) do |stdin|
+      stdin.write(file.read)
+    end
+
+    execute(['update-index', '--add', '--cacheinfo', '100644', blob_id[0], dst_path])
+
+    tree_id = execute(['write-tree'])
+
+    commit_tree_args = ['commit-tree', tree_id[0], '-m', "Add #{dst_path}"]
+    commit_tree_args += ['-p', head_id] unless head_id == EMPTY_TREE_ID
+    commit_id = execute(commit_tree_args)
+
+    execute(['update-ref', "refs/heads/#{branch}", commit_id[0]])
+  end
+
+  private
+
+  def execute(args, allow_failure: false)
+    output, status = popen(base_args + args, nil) do |stdin|
+      yield stdin if block_given?
+    end
+
+    unless status.zero?
+      if allow_failure
+        return []
+      else
+        raise "Got a non-zero exit code while calling out `#{args.join(' ')}`: #{output}"
+      end
+    end
+
+    output.split("\n")
+  end
+
+  def base_args
+    [
+      Gitlab.config.git.bin_path,
+      "--git-dir=#{@path_to_repo}"
+    ]
+  end
+end