Comment on any expanded diff line on MRs

16 files changed, 1154 insertions, 52 deletions

diff --git a/app/assets/javascripts/diffs/components/diff_line_gutter_content.vue b/app/assets/javascripts/diffs/components/diff_line_gutter_content.vue
index 6eff3013dcd..9fe1903ee7c 100644
--- a/app/assets/javascripts/diffs/components/diff_line_gutter_content.vue
+++ b/app/assets/javascripts/diffs/components/diff_line_gutter_content.vue
@@ -81,7 +81,6 @@ export default {
         this.showCommentButton &&
         this.isHover &&
         !this.isMatchLine &&
-        !this.isContextLine &&
         !this.isMetaLine &&
         !this.hasDiscussions
       );
diff --git a/app/assets/javascripts/diffs/components/diff_table_cell.vue b/app/assets/javascripts/diffs/components/diff_table_cell.vue
index 5d9a0b123fe..5201f681e16 100644
--- a/app/assets/javascripts/diffs/components/diff_table_cell.vue
+++ b/app/assets/javascripts/diffs/components/diff_table_cell.vue
@@ -91,7 +91,6 @@ export default {
           this.isLoggedIn &&
           this.isHover &&
           !this.isMatchLine &&
-          !this.isContextLine &&
           !this.isMetaLine,
       };
     },
diff --git a/app/assets/javascripts/diffs/components/parallel_diff_table_row.vue b/app/assets/javascripts/diffs/components/parallel_diff_table_row.vue
index fcc3b3e9117..5419aff23d2 100644
--- a/app/assets/javascripts/diffs/components/parallel_diff_table_row.vue
+++ b/app/assets/javascripts/diffs/components/parallel_diff_table_row.vue
@@ -48,7 +48,6 @@ export default {
     },
     classNameMap() {
       return {
-        [CONTEXT_LINE_CLASS_NAME]: this.isContextLine,
         [PARALLEL_DIFF_VIEW_TYPE]: true,
       };
     },
diff --git a/app/assets/javascripts/diffs/store/mutations.js b/app/assets/javascripts/diffs/store/mutations.js
index 38a65f111a2..15619728fe6 100644
--- a/app/assets/javascripts/diffs/store/mutations.js
+++ b/app/assets/javascripts/diffs/store/mutations.js
@@ -65,7 +65,14 @@ export default {
     const { highlightedDiffLines, parallelDiffLines } = diffFile;
 
     removeMatchLine(diffFile, lineNumbers, bottom);
-    const lines = addLineReferences(contextLines, lineNumbers, bottom);
+
+    const lines = addLineReferences(contextLines, lineNumbers, bottom)
+      .map(line => ({
+        ...line,
+        lineCode: line.lineCode || `${fileHash}_${line.oldLine}_${line.newLine}`,
+        discussions: line.discussions || [],
+      }));
+
     addContextLines({
       inlineLines: highlightedDiffLines,
       parallelLines: parallelDiffLines,
diff --git a/app/controllers/projects/blob_controller.rb b/app/controllers/projects/blob_controller.rb
index 56a884b8a2a..b35d602fb76 100644
--- a/app/controllers/projects/blob_controller.rb
+++ b/app/controllers/projects/blob_controller.rb
@@ -122,7 +122,7 @@ class Projects::BlobController < Projects::ApplicationController
     @lines.map! do |line|
       # These are marked as context lines but are loaded from blobs.
       # We also have context lines loaded from diffs in other places.
-      diff_line = Gitlab::Diff::Line.new(line, 'context', nil, nil, nil)
+      diff_line = Gitlab::Diff::Line.new(line, nil, nil, nil, nil)
       diff_line.rich_text = line
       diff_line
     end
diff --git a/app/controllers/projects/merge_requests/diffs_controller.rb b/app/controllers/projects/merge_requests/diffs_controller.rb
index 5307cd0720a..0d9a991d21e 100644
--- a/app/controllers/projects/merge_requests/diffs_controller.rb
+++ b/app/controllers/projects/merge_requests/diffs_controller.rb
@@ -22,8 +22,13 @@ class Projects::MergeRequests::DiffsController < Projects::MergeRequests::Applic
 
   def render_diffs
     @environment = @merge_request.environments_for(current_user).last
+    notes_grouped_by_old_path = @notes.group_by { |note| note.position.old_path }
 
-    @diffs.write_cache
+    # @diffs.write_cache
+    @diffs.diff_files.each do |diff_file|
+      notes = notes_grouped_by_old_path.fetch(diff_file.old_path, [])
+      notes.each { |note| diff_file.unfold_diff_lines(note.position) }
+    end
 
     request = {
       current_user: current_user,
diff --git a/app/models/diff_note.rb b/app/models/diff_note.rb
index 95694377fe3..d1360d548f6 100644
--- a/app/models/diff_note.rb
+++ b/app/models/diff_note.rb
@@ -80,22 +80,29 @@ class DiffNote < Note
   end
 
   def fetch_diff_file
-    if note_diff_file
-      diff = Gitlab::Git::Diff.new(note_diff_file.to_hash)
-      Gitlab::Diff::File.new(diff,
-                             repository: project.repository,
-                             diff_refs: original_position.diff_refs)
-    elsif created_at_diff?(noteable.diff_refs)
-      # We're able to use the already persisted diffs (Postgres) if we're
-      # presenting a "current version" of the MR discussion diff.
-      # So no need to make an extra Gitaly diff request for it.
-      # As an extra benefit, the returned `diff_file` already
-      # has `highlighted_diff_lines` data set from Redis on
-      # `Diff::FileCollection::MergeRequestDiff`.
-      noteable.diffs(original_position.diff_options).diff_files.first
-    else
-      original_position.diff_file(self.project.repository)
-    end
+    file =
+      if note_diff_file
+        diff = Gitlab::Git::Diff.new(note_diff_file.to_hash)
+        Gitlab::Diff::File.new(diff,
+                               repository: project.repository,
+                               diff_refs: original_position.diff_refs)
+      elsif created_at_diff?(noteable.diff_refs)
+        # We're able to use the already persisted diffs (Postgres) if we're
+        # presenting a "current version" of the MR discussion diff.
+        # So no need to make an extra Gitaly diff request for it.
+        # As an extra benefit, the returned `diff_file` already
+        # has `highlighted_diff_lines` data set from Redis on
+        # `Diff::FileCollection::MergeRequestDiff`.
+        noteable.diffs(original_position.diff_options).diff_files.first
+      else
+        original_position.diff_file(self.project.repository)
+      end
+
+    # Since persisted diff files already have its content "unfolded"
+    # there's no need to make it pass through the unfolding process.
+    file&.unfold_diff_lines(position) unless note_diff_file
+
+    file
   end
 
   def supported?
diff --git a/changelogs/unreleased/osw-comment-on-any-line-on-diffs.yml b/changelogs/unreleased/osw-comment-on-any-line-on-diffs.yml
new file mode 100644
index 00000000000..de9d1ab16fe
--- /dev/null
+++ b/changelogs/unreleased/osw-comment-on-any-line-on-diffs.yml
@@ -0,0 +1,5 @@
+---
+title: Allow commenting on any diff line in Merge Requests
+merge_request:
+author:
+type: added
diff --git a/lib/gitlab/diff/expander.rb b/lib/gitlab/diff/expander.rb
new file mode 100644
index 00000000000..71c28f2e4d3
--- /dev/null
+++ b/lib/gitlab/diff/expander.rb
@@ -0,0 +1,198 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module Diff
+    class Expander
+      include Gitlab::Utils::StrongMemoize
+
+      UNFOLD_COUNT = 20
+
+      def initialize(diff_file, position)
+        @diff_file = diff_file
+        @blob = diff_file.old_blob
+        @position = position
+        @unfold = true
+      end
+
+      # Returns merged diff lines with required blob lines for presenting.
+      def diff_lines
+        strong_memoize(:diff_lines) do
+          original_diff_lines = @diff_file.diff_lines
+
+          next original_diff_lines unless should_expand?
+
+          merged_diff_with_blob_lines(original_diff_lines)
+        end
+      end
+
+      # Returns the extracted lines from the old blob which should be merged
+      # with the current diff lines.
+      def blob_lines
+        strong_memoize(:blob_lines) do
+          @blob.load_all_data!
+
+          # Blob lines, unlike diffs, doesn't start with an empty line for
+          # unchanged line, so the parsing and highlighting step gets fuzzy.
+          line_prefix = ' '
+          blob_as_diff_lines = @blob.data.each_line.map { |line| "#{line_prefix}#{line}" }
+
+          lines = Gitlab::Diff::Parser.new.parse(blob_as_diff_lines, diff_file: @diff_file).to_a
+
+          from = from_blob_line - 1
+          to = to_blob_line - 1
+
+          lines[from..to]
+        end
+      end
+
+      private
+
+      def should_expand?
+        return false unless @diff_file.text?
+        return false if @blob.nil?
+        return false unless @position.old_line
+        return false if @diff_file.diff_lines.empty?
+        return false if @diff_file.line_for_position(@position)
+        return false unless expanded_line
+
+        true
+      end
+
+      def merged_diff_with_blob_lines(lines)
+        match_line = expanded_line
+        insert_index = bottom? ? -1 : match_line.index
+
+        lines -= [match_line] unless bottom?
+
+        lines.insert(insert_index, *blob_lines_with_new_match)
+
+        # The inserted blob lines have invalid indexes, so we need
+        # to reindex them.
+        reindex(lines)
+
+        lines
+      end
+
+      # Returns 'unchanged' blob lines with recalculated `old_pos` and
+      # `new_pos` and the recalculated new match line (needed if we for instance
+      # we unfolded once, but there are still folded lines).
+      def blob_lines_with_new_match
+        old_pos = from_blob_line
+        new_pos = from_blob_line + offset
+
+        new_blob_lines = []
+
+        blob_lines.each do |line|
+          new_blob_lines << Gitlab::Diff::Line.new(line.text, line.type, nil, old_pos, new_pos,
+                                                   parent_file: @diff_file)
+
+          old_pos += 1
+          new_pos += 1
+        end
+
+        new_blob_lines.unshift(new_match_line) if new_match_line
+
+        new_blob_lines
+      end
+
+      def bottom?
+        @position.old_line > @diff_file.diff_lines.last.old_pos
+      end
+
+      def reindex(lines)
+        lines.each_with_index { |line, i| line.index = i }
+      end
+
+      def new_match_line
+        # The bottom line match addition is already handled on
+        # Diff::File#diff_lines_for_serializer
+        return if bottom?
+        return unless @unfold
+
+        blob_lines_length = blob_lines.length - 1
+
+        # This will change for bottom scenarios
+        old_pos = from_blob_line
+        new_pos = from_blob_line + offset
+
+        old_line_ref = [old_pos, blob_lines_length].join(',')
+        new_line_ref = [new_pos, blob_lines_length].join(',')
+        new_match_line_str = "@@ -#{old_line_ref}+#{new_line_ref} @@"
+
+        Gitlab::Diff::Line.new(new_match_line_str, 'match', nil, old_pos, new_pos)
+      end
+
+      # TODO: use similar approach used on `to_bottom_blob_line` (this will
+      # change)
+      def from_blob_line
+        return old_line_number + 1 if bottom?
+
+        unfold_times = 1
+        comment_position = @position.old_line
+        index_line = line_number_above_match
+
+        while (from = index_line - (UNFOLD_COUNT * unfold_times)) > comment_position
+          index_line -= 1
+          unfold_times += 1
+        end
+
+        prev_line_number = line_before_match&.old_pos || 0
+
+        if from <= prev_line_number + 1
+          @unfold = false
+          from = prev_line_number + 1
+        end
+
+        from
+      end
+
+      def to_blob_line
+        if bottom?
+          # Calculates unfolding times based on how many lines between the
+          # comment position and the bottom match line it has.
+          from = from_blob_line
+          comment_position = @position.old_line
+          unfold_times = ((comment_position - from_blob_line).to_f / (UNFOLD_COUNT + 1)).ceil
+          from + (UNFOLD_COUNT * unfold_times) + (unfold_times - 1)
+        else
+          line_number_above_match
+        end
+      end
+
+      def line_number_above_match
+        old_line_number - 1
+      end
+
+      def offset
+        new_line_number - old_line_number
+      end
+
+      def old_line_number
+        expanded_line.old_pos
+      end
+
+      def new_line_number
+        expanded_line.new_pos
+      end
+
+      def line_before_match
+        index = expanded_line&.index
+
+        @diff_file.diff_lines[index - 1] if index > 0
+      end
+
+      # Returns the line which needed to be expanded in order to send a comment
+      # in `@position`.
+      def expanded_line
+        strong_memoize(:expanded_line) do
+          if bottom?
+            @diff_file.diff_lines.last
+          else
+            @diff_file.diff_lines
+              .find { |line| line.old_pos > @position.old_line && line.type == 'match' }
+          end
+        end
+      end
+    end
+  end
+end
diff --git a/lib/gitlab/diff/file.rb b/lib/gitlab/diff/file.rb
index fb117baca9e..098633327fe 100644
--- a/lib/gitlab/diff/file.rb
+++ b/lib/gitlab/diff/file.rb
@@ -127,6 +127,7 @@ module Gitlab
         new_blob || old_blob
       end
 
+      attr_writer :diff_lines
       attr_writer :highlighted_diff_lines
 
       # Array of Gitlab::Diff::Line objects
@@ -135,11 +136,38 @@ module Gitlab
           Gitlab::Diff::Parser.new.parse(raw_diff.each_line, diff_file: self).to_a
       end
 
+      # Changes diff_lines according to the given position. That is,
+      # it checks whether the position requires blob lines into the diff
+      # in order to be presented.
+      def unfold_diff_lines(position)
+        return unless position
+
+        self.diff_lines = Gitlab::Diff::Expander.new(self, position).diff_lines
+      end
+
       def highlighted_diff_lines
         @highlighted_diff_lines ||=
           Gitlab::Diff::Highlight.new(self, repository: self.repository).highlight
       end
 
+      # This adds the bottom match line to the array if needed. It contains
+      # the data to load more context lines.
+      def diff_lines_for_serializer
+        lines = highlighted_diff_lines
+
+        return if lines.empty?
+        return if blob.nil?
+
+        last_line = lines.last
+
+        if last_line.new_pos < total_blob_lines(blob) && !deleted_file?
+          match_line = Gitlab::Diff::Line.new("", 'match', nil, last_line.old_pos, last_line.new_pos)
+          lines.push(match_line)
+        end
+
+        lines
+      end
+
       # Array[<Hash>] with right/left keys that contains Gitlab::Diff::Line objects which text is hightlighted
       def parallel_diff_lines
         @parallel_diff_lines ||= Gitlab::Diff::ParallelDiff.new(self).parallelize
@@ -246,24 +274,6 @@ module Gitlab
         simple_viewer.is_a?(DiffViewer::Text) && (ignore_errors || simple_viewer.render_error.nil?)
       end
 
-      # This adds the bottom match line to the array if needed. It contains
-      # the data to load more context lines.
-      def diff_lines_for_serializer
-        lines = highlighted_diff_lines
-
-        return if lines.empty?
-        return if blob.nil?
-
-        last_line = lines.last
-
-        if last_line.new_pos < total_blob_lines(blob) && !deleted_file?
-          match_line = Gitlab::Diff::Line.new("", 'match', nil, last_line.old_pos, last_line.new_pos)
-          lines.push(match_line)
-        end
-
-        lines
-      end
-
       private
 
       def total_blob_lines(blob)
diff --git a/lib/gitlab/diff/file_collection/merge_request_diff.rb b/lib/gitlab/diff/file_collection/merge_request_diff.rb
index 0dd073a3a8e..7d772e1a66d 100644
--- a/lib/gitlab/diff/file_collection/merge_request_diff.rb
+++ b/lib/gitlab/diff/file_collection/merge_request_diff.rb
@@ -17,7 +17,8 @@ module Gitlab
         def diff_files
           diff_files = super
 
-          diff_files.each { |diff_file| cache.decorate(diff_file) }
+          # TODO: Fix highlight caching.
+          # diff_files.each { |diff_file| cache.decorate(diff_file) }
 
           diff_files
         end
diff --git a/lib/gitlab/diff/line.rb b/lib/gitlab/diff/line.rb
index 5b67cd46c48..fcc4be42e4f 100644
--- a/lib/gitlab/diff/line.rb
+++ b/lib/gitlab/diff/line.rb
@@ -4,7 +4,7 @@ module Gitlab
       SERIALIZE_KEYS = %i(line_code rich_text text type index old_pos new_pos).freeze
 
       attr_reader :line_code, :type, :index, :old_pos, :new_pos
-      attr_writer :rich_text
+      attr_writer :rich_text, :index
       attr_accessor :text
 
       def initialize(text, type, index, old_pos, new_pos, parent_file: nil, line_code: nil, rich_text: nil)
@@ -19,7 +19,14 @@ module Gitlab
       end
 
       def self.init_from_hash(hash)
-        new(hash[:text], hash[:type], hash[:index], hash[:old_pos], hash[:new_pos], line_code: hash[:line_code], rich_text: hash[:rich_text])
+        new(hash[:text],
+            hash[:type],
+            hash[:index],
+            hash[:old_pos],
+            hash[:new_pos],
+            parent_file: hash[:parent_file],
+            line_code: hash[:line_code],
+            rich_text: hash[:rich_text])
       end
 
       def to_hash
diff --git a/lib/gitlab/diff/position.rb b/lib/gitlab/diff/position.rb
index f967494199e..89b01bf9296 100644
--- a/lib/gitlab/diff/position.rb
+++ b/lib/gitlab/diff/position.rb
@@ -134,7 +134,13 @@ module Gitlab
         return unless diff_refs.complete?
         return unless comparison = diff_refs.compare_in(repository.project)
 
-        comparison.diffs(diff_options).diff_files.first
+        file = comparison.diffs(diff_options).diff_files.first
+
+        # We need to unfold diff lines according to the position in order
+        # to correctly calculate the line code and trace position changes.
+        file.unfold_diff_lines(self)
+
+        file
       end
 
       def get_formatter_class(type)
diff --git a/spec/controllers/projects/blob_controller_spec.rb b/spec/controllers/projects/blob_controller_spec.rb
index 64b589a6d83..f58aa25cbdd 100644
--- a/spec/controllers/projects/blob_controller_spec.rb
+++ b/spec/controllers/projects/blob_controller_spec.rb
@@ -157,7 +157,7 @@ describe Projects::BlobController do
 
             match_line = JSON.parse(response.body).first
 
-            expect(match_line['type']).to eq('context')
+            expect(match_line['type']).to be_nil
           end
 
           it 'adds bottom match line when "t"o is less than blob size' do
@@ -177,7 +177,7 @@ describe Projects::BlobController do
 
             match_line = JSON.parse(response.body).last
 
-            expect(match_line['type']).to eq('context')
+            expect(match_line['type']).to be_nil
           end
         end
       end
diff --git a/spec/features/merge_request/user_posts_diff_notes_spec.rb b/spec/features/merge_request/user_posts_diff_notes_spec.rb
index fa148715855..51b78d3e7d1 100644
--- a/spec/features/merge_request/user_posts_diff_notes_spec.rb
+++ b/spec/features/merge_request/user_posts_diff_notes_spec.rb
@@ -85,12 +85,13 @@ describe 'Merge request > User posts diff notes', :js do
       # `.line_holder` will be an unfolded line.
       let(:line_holder) { first('#a5cc2925ca8258af241be7e5b0381edf30266302 .line_holder') }
 
-      it 'does not allow commenting on the left side' do
-        should_not_allow_commenting(line_holder, 'left')
+      it 'allows commenting on the left side' do
+        should_allow_commenting(line_holder, 'left')
       end
 
-      it 'does not allow commenting on the right side' do
-        should_not_allow_commenting(line_holder, 'right')
+      it 'allows commenting on the right side' do
+        # Automatically shifts comment box to left side.
+        should_allow_commenting(line_holder, 'right')
       end
     end
   end
@@ -147,8 +148,8 @@ describe 'Merge request > User posts diff notes', :js do
       # `.line_holder` will be an unfolded line.
       let(:line_holder) { first('.line_holder[id="a5cc2925ca8258af241be7e5b0381edf30266302_1_1"]') }
 
-      it 'does not allow commenting' do
-        should_not_allow_commenting line_holder
+      it 'allows commenting' do
+        should_allow_commenting line_holder
       end
     end
 
diff --git a/spec/lib/gitlab/diff/expander_spec.rb b/spec/lib/gitlab/diff/expander_spec.rb
new file mode 100644
index 00000000000..50ab0a27b7a
--- /dev/null
+++ b/spec/lib/gitlab/diff/expander_spec.rb
@@ -0,0 +1,858 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe Gitlab::Diff::Expander do
+  include RepoHelpers
+
+  let(:raw_diff) do
+    ["@@ -7,9 +7,6 @@\n",
+     "     \"tags\": [\"devel\", \"development\", \"nightly\"],\n",
+     "     \"desktop-file-name-prefix\": \"(Development) \",\n",
+     "     \"finish-args\": [\n",
+     "-        \"--share=ipc\", \"--socket=x11\",\n",
+     "-        \"--socket=wayland\",\n",
+     "-        \"--talk-name=org.gnome.OnlineAccounts\",\n",
+     "         \"--talk-name=org.freedesktop.Tracker1\",\n",
+     "         \"--filesystem=home\",\n",
+     "         \"--talk-name=org.gtk.vfs\", \"--talk-name=org.gtk.vfs.*\",\n",
+     "@@ -62,7 +59,7 @@\n",
+     "         },\n",
+     "         {\n",
+     "             \"name\": \"gnome-desktop\",\n",
+     "-            \"config-opts\": [\"--disable-debug-tools\", \"--disable-udev\"],\n",
+     "+            \"config-opts\": [\"--disable-debug-tools\", \"--disable-\"],\n",
+     "             \"sources\": [\n",
+     "                 {\n",
+     "                     \"type\": \"git\",\n",
+     "@@ -83,11 +80,6 @@\n",
+     "             \"buildsystem\": \"meson\",\n",
+     "             \"builddir\": true,\n",
+     "             \"name\": \"nautilus\",\n",
+     "-            \"config-opts\": [\n",
+     "-                \"-Denable-desktop=false\",\n",
+     "-                \"-Denable-selinux=false\",\n",
+     "-                \"--libdir=/app/lib\"\n",
+     "-            ],\n",
+     "             \"sources\": [\n",
+     "                 {\n",
+     "                     \"type\": \"git\",\n"].join
+  end
+
+  let(:raw_old_blob) do
+    ["{\n",
+     "    \"app-id\": \"org.gnome.Nautilus\",\n",
+     "    \"runtime\": \"org.gnome.Platform\",\n",
+     "    \"runtime-version\": \"master\",\n",
+     "    \"sdk\": \"org.gnome.Sdk\",\n",
+     "    \"command\": \"nautilus\",\n",
+     "    \"tags\": [\"devel\", \"development\", \"nightly\"],\n",
+     "    \"desktop-file-name-prefix\": \"(Development) \",\n",
+     "    \"finish-args\": [\n",
+     "        \"--share=ipc\", \"--socket=x11\",\n",
+     "        \"--socket=wayland\",\n",
+     "        \"--talk-name=org.gnome.OnlineAccounts\",\n",
+     "        \"--talk-name=org.freedesktop.Tracker1\",\n",
+     "        \"--filesystem=home\",\n",
+     "        \"--talk-name=org.gtk.vfs\", \"--talk-name=org.gtk.vfs.*\",\n",
+     "        \"--filesystem=xdg-run/dconf\", \"--filesystem=~/.config/dconf:ro\",\n",
+     "        \"--talk-name=ca.desrt.dconf\", \"--env=DCONF_USER_CONFIG_DIR=.config/dconf\"\n",
+     "    ],\n",
+     "    \"cleanup\": [ \"/include\", \"/share/bash-completion\" ],\n",
+     "    \"modules\": [\n",
+     "        {\n",
+     "            \"name\": \"exiv2\",\n",
+     "            \"sources\": [\n",
+     "                {\n",
+     "                    \"type\": \"archive\",\n",
+     "                    \"url\": \"http://exiv2.org/builds/exiv2-0.26-trunk.tar.gz\",\n",
+     "                    \"sha256\": \"c75e3c4a0811bf700d92c82319373b7a825a2331c12b8b37d41eb58e4f18eafb\"\n",
+     "                },\n",
+     "                {\n",
+     "                    \"type\": \"shell\",\n",
+     "                    \"commands\": [\n",
+     "                        \"cp -f /usr/share/gnu-config/config.sub ./config/\",\n",
+     "                        \"cp -f /usr/share/gnu-config/config.guess ./config/\"\n",
+     "                    ]\n",
+     "                }\n",
+     "            ]\n",
+     "        },\n",
+     "        {\n",
+     "            \"name\": \"gexiv2\",\n",
+     "            \"config-opts\": [ \"--disable-introspection\" ],\n",
+     "            \"sources\": [\n",
+     "                {\n",
+     "                    \"type\": \"git\",\n",
+     "                    \"url\": \"https://git.gnome.org/browse/gexiv2\"\n",
+     "                }\n",
+     "            ]\n",
+     "        },\n",
+     "        {\n",
+     "            \"name\": \"tracker\",\n",
+     "            \"cleanup\": [ \"/bin\", \"/etc\", \"/libexec\" ],\n",
+     "            \"config-opts\": [ \"--disable-miner-apps\", \"--disable-static\",\n",
+     "                             \"--disable-tracker-extract\", \"--disable-tracker-needle\",\n",
+     "                             \"--disable-tracker-preferences\", \"--disable-artwork\",\n",
+     "                             \"--disable-tracker-writeback\", \"--disable-miner-user-guides\",\n",
+     "                             \"--with-bash-completion-dir=no\" ],\n",
+     "            \"sources\": [\n",
+     "                {\n",
+     "                    \"type\": \"git\",\n",
+     "                    \"url\": \"https://git.gnome.org/browse/tracker\"\n",
+     "                }\n",
+     "            ]\n",
+     "        },\n",
+     "        {\n",
+     "            \"name\": \"gnome-desktop\",\n",
+     "            \"config-opts\": [\"--disable-debug-tools\", \"--disable-udev\"],\n",
+     "            \"sources\": [\n",
+     "                {\n",
+     "                    \"type\": \"git\",\n",
+     "                    \"url\": \"https://git.gnome.org/browse/gnome-desktop\"\n",
+     "                }\n",
+     "            ]\n",
+     "        },\n",
+     "        {\n",
+     "            \"name\": \"gnome-autoar\",\n",
+     "            \"sources\": [\n",
+     "                {\n",
+     "                    \"type\": \"git\",\n",
+     "                    \"url\": \"https://git.gnome.org/browse/gnome-autoar\"\n",
+     "                }\n",
+     "            ]\n",
+     "        },\n",
+     "        {\n",
+     "            \"buildsystem\": \"meson\",\n",
+     "            \"builddir\": true,\n",
+     "            \"name\": \"nautilus\",\n",
+     "            \"config-opts\": [\n",
+     "                \"-Denable-desktop=false\",\n",
+     "                \"-Denable-selinux=false\",\n",
+     "                \"--libdir=/app/lib\"\n",
+     "            ],\n",
+     "            \"sources\": [\n",
+     "                {\n",
+     "                    \"type\": \"git\",\n",
+     "                    \"url\": \"https://gitlab.gnome.org/GNOME/nautilus.git\"\n",
+     "                }\n",
+     "            ]\n",
+     "        }\n",
+     "    ]\n",
+     "},\n",
+     "{\n",
+     "    \"app-id\": \"foo\",\n",
+     "    \"runtime\": \"foo\",\n",
+     "    \"runtime-version\": \"foo\",\n",
+     "    \"sdk\": \"foo\",\n",
+     "    \"command\": \"foo\",\n",
+     "    \"tags\": [\"foo\", \"bar\", \"kux\"],\n",
+     "    \"desktop-file-name-prefix\": \"(Foo) \",\n",
+     "    {\n",
+     "      \"buildsystem\": \"meson\",\n",
+     "      \"builddir\": true,\n",
+     "      \"name\": \"nautilus\",\n",
+     "      \"sources\": [\n",
+     "        {\n",
+     "          \"type\": \"git\",\n",
+     "          \"url\": \"https://gitlab.gnome.org/GNOME/nautilus.git\"\n",
+     "        }\n",
+     "      ]\n",
+     "    }\n",
+     "},\n",
+     "{\n",
+     "    \"app-id\": \"foo\",\n",
+     "    \"runtime\": \"foo\",\n",
+     "    \"runtime-version\": \"foo\",\n",
+     "    \"sdk\": \"foo\",\n",
+     "    \"command\": \"foo\",\n",
+     "    \"tags\": [\"foo\", \"bar\", \"kux\"],\n",
+     "    \"desktop-file-name-prefix\": \"(Foo) \",\n",
+     "    {\n",
+     "      \"buildsystem\": \"meson\",\n",
+     "      \"builddir\": true,\n",
+     "      \"name\": \"nautilus\",\n",
+     "      \"sources\": [\n",
+     "        {\n",
+     "          \"type\": \"git\",\n",
+     "          \"url\": \"https://gitlab.gnome.org/GNOME/nautilus.git\"\n",
+     "        }\n",
+     "      ]\n",
+     "    }\n",
+     "}\n"].join
+  end
+
+  let(:project) { create(:project) }
+
+  let(:old_blob) { Gitlab::Git::Blob.new(data: raw_old_blob) }
+
+  let(:diff) do
+    Gitlab::Git::Diff.new(diff: raw_diff,
+                          new_path: "build-aux/flatpak/org.gnome.Nautilus.json",
+                          old_path: "build-aux/flatpak/org.gnome.Nautilus.json",
+                          a_mode: "100644",
+                          b_mode: "100644",
+                          new_file: false,
+                          renamed_file: false,
+                          deleted_file: false,
+                          too_large: false)
+  end
+
+  let(:diff_file) do
+    Gitlab::Diff::File.new(diff, repository: project.repository)
+  end
+
+  before do
+    allow(old_blob).to receive(:load_all_data!)
+    allow(diff_file).to receive(:old_blob) { old_blob }
+  end
+
+  subject { described_class.new(diff_file, position) }
+
+  context 'position requires a single middle expansion' do
+    let(:position) do
+      Gitlab::Diff::Position.new(base_sha: "1c59dfa64afbea8c721bb09a06a9d326c952ea19",
+                                 start_sha: "1c59dfa64afbea8c721bb09a06a9d326c952ea19",
+                                 head_sha: "1487062132228de836236c522fe52fed4980a46c",
+                                 old_path: "build-aux/flatpak/org.gnome.Nautilus.json",
+                                 new_path: "build-aux/flatpak/org.gnome.Nautilus.json",
+                                 position_type:  "text",
+                                 old_line: 43,
+                                 new_line: 40)
+    end
+
+    context 'blob lines' do
+      let(:expected_blob_lines) do
+        [[41, 41, "             \"sources\": ["],
+         [42, 42, "                 {"],
+         [43, 43, "                     \"type\": \"git\","],
+         [44, 44, "                     \"url\": \"https://git.gnome.org/browse/gexiv2\""],
+         [45, 45, "                 }"],
+         [46, 46, "             ]"],
+         [47, 47, "         },"],
+         [48, 48, "         {"],
+         [49, 49, "             \"name\": \"tracker\","],
+         [50, 50, "             \"cleanup\": [ \"/bin\", \"/etc\", \"/libexec\" ],"],
+         [51, 51, "             \"config-opts\": [ \"--disable-miner-apps\", \"--disable-static\","],
+         [52, 52, "                              \"--disable-tracker-extract\", \"--disable-tracker-needle\","],
+         [53, 53, "                              \"--disable-tracker-preferences\", \"--disable-artwork\","],
+         [54, 54, "                              \"--disable-tracker-writeback\", \"--disable-miner-user-guides\","],
+         [55, 55, "                              \"--with-bash-completion-dir=no\" ],"],
+         [56, 56, "             \"sources\": ["],
+         [57, 57, "                 {"],
+         [58, 58, "                     \"type\": \"git\","],
+         [59, 59, "                     \"url\": \"https://git.gnome.org/browse/tracker\""],
+         [60, 60, "                 }"],
+         [61, 61, "             ]"]]
+      end
+
+      it 'returns the extracted blob lines correctly' do
+        extracted_lines = subject.blob_lines
+
+        expect(extracted_lines.size).to eq(21)
+
+        extracted_lines.each_with_index do |line, i|
+          expect([line.old_line, line.new_line, line.text]).to eq(expected_blob_lines[i])
+        end
+      end
+    end
+
+    context 'diff lines' do
+      let(:expected_diff_lines) do
+        [[7, 7, "@@ -7,9 +7,6 @@"],
+         [7, 7, "     \"tags\": [\"devel\", \"development\", \"nightly\"],"],
+         [8, 8, "     \"desktop-file-name-prefix\": \"(Development) \","],
+         [9, 9, "     \"finish-args\": ["],
+         [10, 10, "-        \"--share=ipc\", \"--socket=x11\","],
+         [11, 10, "-        \"--socket=wayland\","],
+         [12, 10, "-        \"--talk-name=org.gnome.OnlineAccounts\","],
+         [13, 10, "         \"--talk-name=org.freedesktop.Tracker1\","],
+         [14, 11, "         \"--filesystem=home\","],
+         [15, 12, "         \"--talk-name=org.gtk.vfs\", \"--talk-name=org.gtk.vfs.*\","],
+
+         # New match line
+         [41, 38, "@@ -41,20+38,20 @@"],
+
+         # Injected blob lines
+         [41, 38, "             \"sources\": ["],
+         [42, 39, "                 {"],
+         [43, 40, "                     \"type\": \"git\","],
+         [44, 41, "                     \"url\": \"https://git.gnome.org/browse/gexiv2\""],
+         [45, 42, "                 }"],
+         [46, 43, "             ]"],
+         [47, 44, "         },"],
+         [48, 45, "         {"],
+         [49, 46, "             \"name\": \"tracker\","],
+         [50, 47, "             \"cleanup\": [ \"/bin\", \"/etc\", \"/libexec\" ],"],
+         [51, 48, "             \"config-opts\": [ \"--disable-miner-apps\", \"--disable-static\","],
+         [52, 49, "                              \"--disable-tracker-extract\", \"--disable-tracker-needle\","],
+         [53, 50, "                              \"--disable-tracker-preferences\", \"--disable-artwork\","],
+         [54, 51, "                              \"--disable-tracker-writeback\", \"--disable-miner-user-guides\","],
+         [55, 52, "                              \"--with-bash-completion-dir=no\" ],"],
+         [56, 53, "             \"sources\": ["],
+         [57, 54, "                 {"],
+         [58, 55, "                     \"type\": \"git\","],
+         [59, 56, "                     \"url\": \"https://git.gnome.org/browse/tracker\""],
+         [60, 57, "                 }"],
+         [61, 58, "             ]"],
+         # end
+
+         [62, 59, "         },"],
+         [63, 60, "         {"],
+         [64, 61, "             \"name\": \"gnome-desktop\","],
+         [65, 62, "-            \"config-opts\": [\"--disable-debug-tools\", \"--disable-udev\"],"],
+         [66, 62, "+            \"config-opts\": [\"--disable-debug-tools\", \"--disable-\"],"],
+         [66, 63, "             \"sources\": ["],
+         [67, 64, "                 {"],
+         [68, 65, "                     \"type\": \"git\","],
+         [83, 80, "@@ -83,11 +80,6 @@"],
+         [83, 80, "             \"buildsystem\": \"meson\","],
+         [84, 81, "             \"builddir\": true,"],
+         [85, 82, "             \"name\": \"nautilus\","],
+         [86, 83, "-            \"config-opts\": ["],
+         [87, 83, "-                \"-Denable-desktop=false\","],
+         [88, 83, "-                \"-Denable-selinux=false\","],
+         [89, 83, "-                \"--libdir=/app/lib\""],
+         [90, 83, "-            ],"],
+         [91, 83, "             \"sources\": ["],
+         [92, 84, "                 {"],
+         [93, 85, "                     \"type\": \"git\","]]
+      end
+
+      it 'return merge of blob lines with diff lines correctly' do
+        new_diff_lines = subject.diff_lines
+
+        expected_diff_lines.each_with_index do |expected_line, i|
+          line = new_diff_lines[i]
+
+          expect([line.old_pos, line.new_pos, line.text])
+            .to eq([expected_line[0], expected_line[1], expected_line[2]])
+        end
+      end
+
+      it 'merged lines have correct line codes' do
+        new_diff_lines = subject.diff_lines
+
+        new_diff_lines.each_with_index do |line, i|
+          old_pos, new_pos = expected_diff_lines[i][0], expected_diff_lines[i][1]
+
+          unless line.type == 'match'
+            expect(line.line_code).to eq(Gitlab::Git.diff_line_code(diff_file.file_path, new_pos, old_pos))
+          end
+        end
+      end
+    end
+  end
+
+  context 'position requires a short top expansion' do
+    let(:position) do
+      Gitlab::Diff::Position.new(base_sha: "1c59dfa64afbea8c721bb09a06a9d326c952ea19",
+                                 start_sha: "1c59dfa64afbea8c721bb09a06a9d326c952ea19",
+                                 head_sha: "1487062132228de836236c522fe52fed4980a46c",
+                                 old_path: "build-aux/flatpak/org.gnome.Nautilus.json",
+                                 new_path: "build-aux/flatpak/org.gnome.Nautilus.json",
+                                 position_type: "text",
+                                 old_line: 4,
+                                 new_line: 4)
+    end
+
+    context 'blob lines' do
+      let(:expected_blob_lines) do
+        [[1, 1, " {"],
+         [2, 2, "     \"app-id\": \"org.gnome.Nautilus\","],
+         [3, 3, "     \"runtime\": \"org.gnome.Platform\","],
+         [4, 4, "     \"runtime-version\": \"master\","],
+         [5, 5, "     \"sdk\": \"org.gnome.Sdk\","],
+         [6, 6, "     \"command\": \"nautilus\","]]
+      end
+
+      it 'returns the extracted blob lines correctly' do
+        extracted_lines = subject.blob_lines
+
+        expect(extracted_lines.size).to eq(6)
+
+        extracted_lines.each_with_index do |line, i|
+          expect([line.old_line, line.new_line, line.text]).to eq(expected_blob_lines[i])
+        end
+      end
+    end
+
+    context 'diff lines' do
+      let(:expected_diff_lines) do
+        # Injected blob lines
+        [[1, 1, " {"],
+         [2, 2, "     \"app-id\": \"org.gnome.Nautilus\","],
+         [3, 3, "     \"runtime\": \"org.gnome.Platform\","],
+         [4, 4, "     \"runtime-version\": \"master\","],
+         [5, 5, "     \"sdk\": \"org.gnome.Sdk\","],
+         [6, 6, "     \"command\": \"nautilus\","],
+         #
+         # No generated match
+
+         [7, 7, "     \"tags\": [\"devel\", \"development\", \"nightly\"],"],
+         [8, 8, "     \"desktop-file-name-prefix\": \"(Development) \","],
+         [9, 9, "     \"finish-args\": ["],
+         [10, 10, "-        \"--share=ipc\", \"--socket=x11\","],
+         [11, 10, "-        \"--socket=wayland\","],
+         [12, 10, "-        \"--talk-name=org.gnome.OnlineAccounts\","],
+         [13, 10, "         \"--talk-name=org.freedesktop.Tracker1\","],
+         [14, 11, "         \"--filesystem=home\","],
+         [15, 12, "         \"--talk-name=org.gtk.vfs\", \"--talk-name=org.gtk.vfs.*\","],
+         [62, 59, "@@ -62,7 +59,7 @@"],
+         [62, 59, "         },"],
+         [63, 60, "         {"],
+         [64, 61, "             \"name\": \"gnome-desktop\","],
+         [65, 62, "-            \"config-opts\": [\"--disable-debug-tools\", \"--disable-udev\"],"],
+         [66, 62, "+            \"config-opts\": [\"--disable-debug-tools\", \"--disable-\"],"],
+         [66, 63, "             \"sources\": ["],
+         [67, 64, "                 {"],
+         [68, 65, "                     \"type\": \"git\","],
+         [83, 80, "@@ -83,11 +80,6 @@"],
+         [83, 80, "             \"buildsystem\": \"meson\","],
+         [84, 81, "             \"builddir\": true,"],
+         [85, 82, "             \"name\": \"nautilus\","],
+         [86, 83, "-            \"config-opts\": ["],
+         [87, 83, "-                \"-Denable-desktop=false\","],
+         [88, 83, "-                \"-Denable-selinux=false\","],
+         [89, 83, "-                \"--libdir=/app/lib\""],
+         [90, 83, "-            ],"],
+         [91, 83, "             \"sources\": ["],
+         [92, 84, "                 {"],
+         [93, 85, "                     \"type\": \"git\","]]
+      end
+
+      it 'return merge of blob lines with diff lines correctly' do
+        new_diff_lines = subject.diff_lines
+
+        expected_diff_lines.each_with_index do |expected_line, i|
+          line = new_diff_lines[i]
+
+          expect([line.old_pos, line.new_pos, line.text])
+            .to eq([expected_line[0], expected_line[1], expected_line[2]])
+        end
+      end
+
+      it 'merged lines have correct line codes' do
+        new_diff_lines = subject.diff_lines
+
+        new_diff_lines.each_with_index do |line, i|
+          old_pos, new_pos = expected_diff_lines[i][0], expected_diff_lines[i][1]
+
+          unless line.type == 'match'
+            expect(line.line_code).to eq(Gitlab::Git.diff_line_code(diff_file.file_path, new_pos, old_pos))
+          end
+        end
+      end
+    end
+  end
+
+  context 'position requires more than one middle expansion' do
+    let(:position) do
+      Gitlab::Diff::Position.new(base_sha: "1c59dfa64afbea8c721bb09a06a9d326c952ea19",
+                                 start_sha: "1c59dfa64afbea8c721bb09a06a9d326c952ea19",
+                                 head_sha: "1487062132228de836236c522fe52fed4980a46c",
+                                 old_path: "build-aux/flatpak/org.gnome.Nautilus.json",
+                                 new_path: "build-aux/flatpak/org.gnome.Nautilus.json",
+                                 position_type: "text",
+                                 old_line: 20,
+                                 new_line: 17)
+    end
+
+    context 'blob lines' do
+      let(:expected_blob_lines) do
+        # Second expansion
+        [[20, 20, "     \"modules\": ["],
+         [21, 21, "         {"],
+         [22, 22, "             \"name\": \"exiv2\","],
+         [23, 23, "             \"sources\": ["],
+         [24, 24, "                 {"],
+         [25, 25, "                     \"type\": \"archive\","],
+         [26, 26, "                     \"url\": \"http://exiv2.org/builds/exiv2-0.26-trunk.tar.gz\","],
+         [27, 27, "                     \"sha256\": \"c75e3c4a0811bf700d92c82319373b7a825a2331c12b8b37d41eb58e4f18eafb\""],
+         [28, 28, "                 },"],
+         [29, 29, "                 {"],
+         [30, 30, "                     \"type\": \"shell\","],
+         [31, 31, "                     \"commands\": ["],
+         [32, 32, "                         \"cp -f /usr/share/gnu-config/config.sub ./config/\","],
+         [33, 33, "                         \"cp -f /usr/share/gnu-config/config.guess ./config/\""],
+         [34, 34, "                     ]"],
+         [35, 35, "                 }"],
+         [36, 36, "             ]"],
+         [37, 37, "         },"],
+         [38, 38, "         {"],
+         [39, 39, "             \"name\": \"gexiv2\","],
+         [40, 40, "             \"config-opts\": [ \"--disable-introspection\" ],"],
+         # First expansion
+         [41, 41, "             \"sources\": ["],
+         [42, 42, "                 {"],
+         [43, 43, "                     \"type\": \"git\","],
+         [44, 44, "                     \"url\": \"https://git.gnome.org/browse/gexiv2\""],
+         [45, 45, "                 }"],
+         [46, 46, "             ]"],
+         [47, 47, "         },"],
+         [48, 48, "         {"],
+         [49, 49, "             \"name\": \"tracker\","],
+         [50, 50, "             \"cleanup\": [ \"/bin\", \"/etc\", \"/libexec\" ],"],
+         [51, 51, "             \"config-opts\": [ \"--disable-miner-apps\", \"--disable-static\","],
+         [52, 52, "                              \"--disable-tracker-extract\", \"--disable-tracker-needle\","],
+         [53, 53, "                              \"--disable-tracker-preferences\", \"--disable-artwork\","],
+         [54, 54, "                              \"--disable-tracker-writeback\", \"--disable-miner-user-guides\","],
+         [55, 55, "                              \"--with-bash-completion-dir=no\" ],"],
+         [56, 56, "             \"sources\": ["],
+         [57, 57, "                 {"],
+         [58, 58, "                     \"type\": \"git\","],
+         [59, 59, "                     \"url\": \"https://git.gnome.org/browse/tracker\""],
+         [60, 60, "                 }"],
+         [61, 61, "             ]"]]
+      end
+
+      it 'returns the extracted blob lines correctly' do
+        extracted_lines = subject.blob_lines
+
+        expect(extracted_lines.size).to eq(42)
+
+        extracted_lines.each_with_index do |line, i|
+          expect([line.old_line, line.new_line, line.text]).to eq(expected_blob_lines[i])
+        end
+      end
+    end
+
+    context 'diff lines' do
+      let(:expected_diff_lines) do
+        [[7, 7, "@@ -7,9 +7,6 @@"],
+         [7, 7, "     \"tags\": [\"devel\", \"development\", \"nightly\"],"],
+         [8, 8, "     \"desktop-file-name-prefix\": \"(Development) \","],
+         [9, 9, "     \"finish-args\": ["],
+         [10, 10, "-        \"--share=ipc\", \"--socket=x11\","],
+         [11, 10, "-        \"--socket=wayland\","],
+         [12, 10, "-        \"--talk-name=org.gnome.OnlineAccounts\","],
+         [13, 10, "         \"--talk-name=org.freedesktop.Tracker1\","],
+         [14, 11, "         \"--filesystem=home\","],
+         [15, 12, "         \"--talk-name=org.gtk.vfs\", \"--talk-name=org.gtk.vfs.*\","],
+         # Generated match line
+         [20, 17, "@@ -20,41+17,41 @@"],
+         # Second expansion
+         [20, 17, "     \"modules\": ["],
+         [21, 18, "         {"],
+         [22, 19, "             \"name\": \"exiv2\","],
+         [23, 20, "             \"sources\": ["],
+         [24, 21, "                 {"],
+         [25, 22, "                     \"type\": \"archive\","],
+         [26, 23, "                     \"url\": \"http://exiv2.org/builds/exiv2-0.26-trunk.tar.gz\","],
+         [27, 24, "                     \"sha256\": \"c75e3c4a0811bf700d92c82319373b7a825a2331c12b8b37d41eb58e4f18eafb\""],
+         [28, 25, "                 },"],
+         [29, 26, "                 {"],
+         [30, 27, "                     \"type\": \"shell\","],
+         [31, 28, "                     \"commands\": ["],
+         [32, 29, "                         \"cp -f /usr/share/gnu-config/config.sub ./config/\","],
+         [33, 30, "                         \"cp -f /usr/share/gnu-config/config.guess ./config/\""],
+         [34, 31, "                     ]"],
+         [35, 32, "                 }"],
+         [36, 33, "             ]"],
+         [37, 34, "         },"],
+         [38, 35, "         {"],
+         [39, 36, "             \"name\": \"gexiv2\","],
+         [40, 37, "             \"config-opts\": [ \"--disable-introspection\" ],"],
+         # First expansion
+         [41, 38, "             \"sources\": ["],
+         [42, 39, "                 {"],
+         [43, 40, "                     \"type\": \"git\","],
+         [44, 41, "                     \"url\": \"https://git.gnome.org/browse/gexiv2\""],
+         [45, 42, "                 }"],
+         [46, 43, "             ]"],
+         [47, 44, "         },"],
+         [48, 45, "         {"],
+         [49, 46, "             \"name\": \"tracker\","],
+         [50, 47, "             \"cleanup\": [ \"/bin\", \"/etc\", \"/libexec\" ],"],
+         [51, 48, "             \"config-opts\": [ \"--disable-miner-apps\", \"--disable-static\","],
+         [52, 49, "                              \"--disable-tracker-extract\", \"--disable-tracker-needle\","],
+         [53, 50, "                              \"--disable-tracker-preferences\", \"--disable-artwork\","],
+         [54, 51, "                              \"--disable-tracker-writeback\", \"--disable-miner-user-guides\","],
+         [55, 52, "                              \"--with-bash-completion-dir=no\" ],"],
+         [56, 53, "             \"sources\": ["],
+         [57, 54, "                 {"],
+         [58, 55, "                     \"type\": \"git\","],
+         [59, 56, "                     \"url\": \"https://git.gnome.org/browse/tracker\""],
+         [60, 57, "                 }"],
+         [61, 58, "             ]"],
+         # end
+         [62, 59, "         },"],
+         [63, 60, "         {"],
+         [64, 61, "             \"name\": \"gnome-desktop\","],
+         [65, 62, "-            \"config-opts\": [\"--disable-debug-tools\", \"--disable-udev\"],"],
+         [66, 62, "+            \"config-opts\": [\"--disable-debug-tools\", \"--disable-\"],"],
+         [66, 63, "             \"sources\": ["],
+         [67, 64, "                 {"],
+         [68, 65, "                     \"type\": \"git\","],
+         [83, 80, "@@ -83,11 +80,6 @@"],
+         [83, 80, "             \"buildsystem\": \"meson\","],
+         [84, 81, "             \"builddir\": true,"],
+         [85, 82, "             \"name\": \"nautilus\","],
+         [86, 83, "-            \"config-opts\": ["],
+         [87, 83, "-                \"-Denable-desktop=false\","],
+         [88, 83, "-                \"-Denable-selinux=false\","],
+         [89, 83, "-                \"--libdir=/app/lib\""],
+         [90, 83, "-            ],"],
+         [91, 83, "             \"sources\": ["],
+         [92, 84, "                 {"],
+         [93, 85, "                     \"type\": \"git\","]]
+      end
+
+      it 'return merge of blob lines with diff lines correctly' do
+        new_diff_lines = subject.diff_lines
+
+        expected_diff_lines.each_with_index do |expected_line, i|
+          line = new_diff_lines[i]
+
+          expect([line.old_pos, line.new_pos, line.text])
+            .to eq([expected_line[0], expected_line[1], expected_line[2]])
+        end
+      end
+
+      it 'merged lines have correct line codes' do
+        new_diff_lines = subject.diff_lines
+
+        new_diff_lines.each_with_index do |line, i|
+          old_pos, new_pos = expected_diff_lines[i][0], expected_diff_lines[i][1]
+
+          unless line.type == 'match'
+            expect(line.line_code).to eq(Gitlab::Git.diff_line_code(diff_file.file_path, new_pos, old_pos))
+          end
+        end
+      end
+    end
+  end
+
+  context 'position sits between two match lines (no expasion needed)' do
+    let(:position) do
+      Gitlab::Diff::Position.new(base_sha: "1c59dfa64afbea8c721bb09a06a9d326c952ea19",
+                                 start_sha: "1c59dfa64afbea8c721bb09a06a9d326c952ea19",
+                                 head_sha: "1487062132228de836236c522fe52fed4980a46c",
+                                 old_path: "build-aux/flatpak/org.gnome.Nautilus.json",
+                                 new_path: "build-aux/flatpak/org.gnome.Nautilus.json",
+                                 position_type: "text",
+                                 old_line: 64,
+                                 new_line: 61)
+    end
+
+    context 'diff lines' do
+      let(:expected_diff_lines) do
+        # No blob lines
+        [[7, 7, "@@ -7,9 +7,6 @@"],
+         [7, 7, "     \"tags\": [\"devel\", \"development\", \"nightly\"],"],
+         [8, 8, "     \"desktop-file-name-prefix\": \"(Development) \","],
+         [9, 9, "     \"finish-args\": ["],
+         [10, 10, "-        \"--share=ipc\", \"--socket=x11\","],
+         [11, 10, "-        \"--socket=wayland\","],
+         [12, 10, "-        \"--talk-name=org.gnome.OnlineAccounts\","],
+         [13, 10, "         \"--talk-name=org.freedesktop.Tracker1\","],
+         [14, 11, "         \"--filesystem=home\","],
+         [15, 12, "         \"--talk-name=org.gtk.vfs\", \"--talk-name=org.gtk.vfs.*\","],
+         [62, 59, "@@ -62,7 +59,7 @@"],
+         [62, 59, "         },"],
+         [63, 60, "         {"],
+         [64, 61, "             \"name\": \"gnome-desktop\","],
+         [65, 62, "-            \"config-opts\": [\"--disable-debug-tools\", \"--disable-udev\"],"],
+         [66, 62, "+            \"config-opts\": [\"--disable-debug-tools\", \"--disable-\"],"],
+         [66, 63, "             \"sources\": ["],
+         [67, 64, "                 {"],
+         [68, 65, "                     \"type\": \"git\","],
+         [83, 80, "@@ -83,11 +80,6 @@"],
+         [83, 80, "             \"buildsystem\": \"meson\","],
+         [84, 81, "             \"builddir\": true,"],
+         [85, 82, "             \"name\": \"nautilus\","],
+         [86, 83, "-            \"config-opts\": ["],
+         [87, 83, "-                \"-Denable-desktop=false\","],
+         [88, 83, "-                \"-Denable-selinux=false\","],
+         [89, 83, "-                \"--libdir=/app/lib\""],
+         [90, 83, "-            ],"],
+         [91, 83, "             \"sources\": ["],
+         [92, 84, "                 {"],
+         [93, 85, "                     \"type\": \"git\","]]
+      end
+
+      it 'return original diff lines' do
+        new_diff_lines = subject.diff_lines
+
+        expected_diff_lines.each_with_index do |expected_line, i|
+          line = new_diff_lines[i]
+
+          expect([line.old_pos, line.new_pos, line.text])
+            .to eq([expected_line[0], expected_line[1], expected_line[2]])
+        end
+      end
+    end
+  end
+
+  context 'bottom position (expansion needed)' do
+    let(:position) do
+      Gitlab::Diff::Position.new(base_sha: "1c59dfa64afbea8c721bb09a06a9d326c952ea19",
+                                 start_sha: "1c59dfa64afbea8c721bb09a06a9d326c952ea19",
+                                 head_sha: "1487062132228de836236c522fe52fed4980a46c",
+                                 old_path: "build-aux/flatpak/org.gnome.Nautilus.json",
+                                 new_path: "build-aux/flatpak/org.gnome.Nautilus.json",
+                                 position_type: "text",
+                                 old_line: 135,
+                                 new_line: 127)
+    end
+
+    context 'blob lines' do
+      let(:expected_blob_lines) do
+        [[94, 94, "                     \"url\": \"https://gitlab.gnome.org/GNOME/nautilus.git\""],
+         [95, 95, "                 }"],
+         [96, 96, "             ]"],
+         [97, 97, "         }"],
+         [98, 98, "     ]"],
+         [99, 99, " },"],
+         [100, 100, " {"],
+         [101, 101, "     \"app-id\": \"foo\","],
+         [102, 102, "     \"runtime\": \"foo\","],
+         [103, 103, "     \"runtime-version\": \"foo\","],
+         [104, 104, "     \"sdk\": \"foo\","],
+         [105, 105, "     \"command\": \"foo\","],
+         [106, 106, "     \"tags\": [\"foo\", \"bar\", \"kux\"],"],
+         [107, 107, "     \"desktop-file-name-prefix\": \"(Foo) \","],
+         [108, 108, "     {"],
+         [109, 109, "       \"buildsystem\": \"meson\","],
+         [110, 110, "       \"builddir\": true,"],
+         [111, 111, "       \"name\": \"nautilus\","],
+         [112, 112, "       \"sources\": ["],
+         [113, 113, "         {"],
+         [114, 114, "           \"type\": \"git\","],
+         [115, 115, "           \"url\": \"https://gitlab.gnome.org/GNOME/nautilus.git\""],
+         [116, 116, "         }"],
+         [117, 117, "       ]"],
+         [118, 118, "     }"],
+         [119, 119, " },"],
+         [120, 120, " {"],
+         [121, 121, "     \"app-id\": \"foo\","],
+         [122, 122, "     \"runtime\": \"foo\","],
+         [123, 123, "     \"runtime-version\": \"foo\","],
+         [124, 124, "     \"sdk\": \"foo\","],
+         [125, 125, "     \"command\": \"foo\","],
+         [126, 126, "     \"tags\": [\"foo\", \"bar\", \"kux\"],"],
+         [127, 127, "     \"desktop-file-name-prefix\": \"(Foo) \","],
+         [128, 128, "     {"],
+         [129, 129, "       \"buildsystem\": \"meson\","],
+         [130, 130, "       \"builddir\": true,"],
+         [131, 131, "       \"name\": \"nautilus\","],
+         [132, 132, "       \"sources\": ["],
+         [133, 133, "         {"],
+         [134, 134, "           \"type\": \"git\","],
+         [135, 135, "           \"url\": \"https://gitlab.gnome.org/GNOME/nautilus.git\""]]
+      end
+
+      it 'returns the extracted blob lines correctly' do
+        extracted_lines = subject.blob_lines
+
+        expect(extracted_lines.size).to eq(42)
+
+        extracted_lines.each_with_index do |line, i|
+          expect([line.old_line, line.new_line, line.text]).to eq(expected_blob_lines[i])
+        end
+      end
+    end
+
+    context 'diff lines' do
+      let(:expected_diff_lines) do
+        [[7, 7, "@@ -7,9 +7,6 @@"],
+         [7, 7, "     \"tags\": [\"devel\", \"development\", \"nightly\"],"],
+         [8, 8, "     \"desktop-file-name-prefix\": \"(Development) \","],
+         [9, 9, "     \"finish-args\": ["],
+         [10, 10, "-        \"--share=ipc\", \"--socket=x11\","],
+         [11, 10, "-        \"--socket=wayland\","],
+         [12, 10, "-        \"--talk-name=org.gnome.OnlineAccounts\","],
+         [13, 10, "         \"--talk-name=org.freedesktop.Tracker1\","],
+         [14, 11, "         \"--filesystem=home\","],
+         [15, 12, "         \"--talk-name=org.gtk.vfs\", \"--talk-name=org.gtk.vfs.*\","],
+         [62, 59, "@@ -62,7 +59,7 @@"],
+         [62, 59, "         },"],
+         [63, 60, "         {"],
+         [64, 61, "             \"name\": \"gnome-desktop\","],
+         [65, 62, "-            \"config-opts\": [\"--disable-debug-tools\", \"--disable-udev\"],"],
+         [66, 62, "+            \"config-opts\": [\"--disable-debug-tools\", \"--disable-\"],"],
+         [66, 63, "             \"sources\": ["],
+         [67, 64, "                 {"],
+         [68, 65, "                     \"type\": \"git\","],
+         [83, 80, "@@ -83,11 +80,6 @@"],
+         [83, 80, "             \"buildsystem\": \"meson\","],
+         [84, 81, "             \"builddir\": true,"],
+         [85, 82, "             \"name\": \"nautilus\","],
+         [86, 83, "-            \"config-opts\": ["],
+         [87, 83, "-                \"-Denable-desktop=false\","],
+         [88, 83, "-                \"-Denable-selinux=false\","],
+         [89, 83, "-                \"--libdir=/app/lib\""],
+         [90, 83, "-            ],"],
+         [91, 83, "             \"sources\": ["],
+         [92, 84, "                 {"],
+         [93, 85, "                     \"type\": \"git\","],
+
+         # Injected blob lines
+         [94, 86, "                     \"url\": \"https://gitlab.gnome.org/GNOME/nautilus.git\""],
+         [95, 87, "                 }"],
+         [96, 88, "             ]"],
+         [97, 89, "         }"],
+         [98, 90, "     ]"],
+         [99, 91, " },"],
+         [100, 92, " {"],
+         [101, 93, "     \"app-id\": \"foo\","],
+         [102, 94, "     \"runtime\": \"foo\","],
+         [103, 95, "     \"runtime-version\": \"foo\","],
+         [104, 96, "     \"sdk\": \"foo\","],
+         [105, 97, "     \"command\": \"foo\","],
+         [106, 98, "     \"tags\": [\"foo\", \"bar\", \"kux\"],"],
+         [107, 99, "     \"desktop-file-name-prefix\": \"(Foo) \","],
+         [108, 100, "     {"],
+         [109, 101, "       \"buildsystem\": \"meson\","],
+         [110, 102, "       \"builddir\": true,"],
+         [111, 103, "       \"name\": \"nautilus\","],
+         [112, 104, "       \"sources\": ["],
+         [113, 105, "         {"],
+         [114, 106, "           \"type\": \"git\","],
+         [115, 107, "           \"url\": \"https://gitlab.gnome.org/GNOME/nautilus.git\""],
+         [116, 108, "         }"],
+         [117, 109, "       ]"],
+         [118, 110, "     }"],
+         [119, 111, " },"],
+         [120, 112, " {"],
+         [121, 113, "     \"app-id\": \"foo\","],
+         [122, 114, "     \"runtime\": \"foo\","],
+         [123, 115, "     \"runtime-version\": \"foo\","],
+         [124, 116, "     \"sdk\": \"foo\","],
+         [125, 117, "     \"command\": \"foo\","],
+         [126, 118, "     \"tags\": [\"foo\", \"bar\", \"kux\"],"],
+         [127, 119, "     \"desktop-file-name-prefix\": \"(Foo) \","],
+         [128, 120, "     {"],
+         [129, 121, "       \"buildsystem\": \"meson\","],
+         [130, 122, "       \"builddir\": true,"],
+         [131, 123, "       \"name\": \"nautilus\","],
+         [132, 124, "       \"sources\": ["],
+         [133, 125, "         {"],
+         [134, 126, "           \"type\": \"git\","],
+         [135, 127, "           \"url\": \"https://gitlab.gnome.org/GNOME/nautilus.git\""]]
+      end
+
+      it 'return merge of blob lines with diff lines correctly' do
+        new_diff_lines = subject.diff_lines
+
+        expected_diff_lines.each_with_index do |expected_line, i|
+          line = new_diff_lines[i]
+
+          expect([line.old_pos, line.new_pos, line.text])
+            .to eq([expected_line[0], expected_line[1], expected_line[2]])
+        end
+      end
+
+      it 'merged lines have correct line codes' do
+        new_diff_lines = subject.diff_lines
+
+        new_diff_lines.each_with_index do |line, i|
+          old_pos, new_pos = expected_diff_lines[i][0], expected_diff_lines[i][1]
+
+          unless line.type == 'match'
+            expect(line.line_code).to eq(Gitlab::Git.diff_line_code(diff_file.file_path, new_pos, old_pos))
+          end
+        end
+      end
+    end
+  end
+end