Revert "Merge branch 'osw-comment-on-any-line-on-diffs' into 'master'"osw-revert-comment-in-any-diff-line

This reverts commit a82a595728d54bdc12e51dfcfb22e9eddc449143, reversing
changes made to e7df959b8f99875edd246c7ac7779c3203e8755e.

26 files changed, 89 insertions, 1234 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 e31a3546b69..f4a9be19496 100644
--- a/app/assets/javascripts/diffs/components/diff_line_gutter_content.vue
+++ b/app/assets/javascripts/diffs/components/diff_line_gutter_content.vue
@@ -55,6 +55,11 @@ export default {
       required: false,
       default: false,
     },
+    isContextLine: {
+      type: Boolean,
+      required: false,
+      default: false,
+    },
     isHover: {
       type: Boolean,
       required: false,
@@ -76,6 +81,7 @@ 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 e26aa9c9b00..5d9a0b123fe 100644
--- a/app/assets/javascripts/diffs/components/diff_table_cell.vue
+++ b/app/assets/javascripts/diffs/components/diff_table_cell.vue
@@ -3,6 +3,7 @@ import { mapGetters } from 'vuex';
 import DiffLineGutterContent from './diff_line_gutter_content.vue';
 import {
   MATCH_LINE_TYPE,
+  CONTEXT_LINE_TYPE,
   EMPTY_CELL_TYPE,
   OLD_LINE_TYPE,
   OLD_NO_NEW_LINE_TYPE,
@@ -70,6 +71,9 @@ export default {
     isMatchLine() {
       return this.line.type === MATCH_LINE_TYPE;
     },
+    isContextLine() {
+      return this.line.type === CONTEXT_LINE_TYPE;
+    },
     isMetaLine() {
       const { type } = this.line;
 
@@ -84,7 +88,11 @@ export default {
         [type]: type,
         [LINE_UNFOLD_CLASS_NAME]: this.isMatchLine,
         [LINE_HOVER_CLASS_NAME]:
-          this.isLoggedIn && this.isHover && !this.isMatchLine && !this.isMetaLine,
+          this.isLoggedIn &&
+          this.isHover &&
+          !this.isMatchLine &&
+          !this.isContextLine &&
+          !this.isMetaLine,
       };
     },
     lineNumber() {
diff --git a/app/assets/javascripts/diffs/components/inline_diff_table_row.vue b/app/assets/javascripts/diffs/components/inline_diff_table_row.vue
index 44c05e4b634..542acd3d930 100644
--- a/app/assets/javascripts/diffs/components/inline_diff_table_row.vue
+++ b/app/assets/javascripts/diffs/components/inline_diff_table_row.vue
@@ -4,6 +4,8 @@ import DiffTableCell from './diff_table_cell.vue';
 import {
   NEW_LINE_TYPE,
   OLD_LINE_TYPE,
+  CONTEXT_LINE_TYPE,
+  CONTEXT_LINE_CLASS_NAME,
   PARALLEL_DIFF_VIEW_TYPE,
   LINE_POSITION_LEFT,
   LINE_POSITION_RIGHT,
@@ -39,9 +41,13 @@ export default {
   },
   computed: {
     ...mapGetters('diffs', ['isInlineView']),
+    isContextLine() {
+      return this.line.type === CONTEXT_LINE_TYPE;
+    },
     classNameMap() {
       return {
         [this.line.type]: this.line.type,
+        [CONTEXT_LINE_CLASS_NAME]: this.isContextLine,
         [PARALLEL_DIFF_VIEW_TYPE]: this.isParallelView,
       };
     },
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 39312cddfce..fcc3b3e9117 100644
--- a/app/assets/javascripts/diffs/components/parallel_diff_table_row.vue
+++ b/app/assets/javascripts/diffs/components/parallel_diff_table_row.vue
@@ -5,6 +5,8 @@ import DiffTableCell from './diff_table_cell.vue';
 import {
   NEW_LINE_TYPE,
   OLD_LINE_TYPE,
+  CONTEXT_LINE_TYPE,
+  CONTEXT_LINE_CLASS_NAME,
   OLD_NO_NEW_LINE_TYPE,
   PARALLEL_DIFF_VIEW_TYPE,
   NEW_NO_NEW_LINE_TYPE,
@@ -41,8 +43,12 @@ export default {
     };
   },
   computed: {
+    isContextLine() {
+      return this.line.left && this.line.left.type === CONTEXT_LINE_TYPE;
+    },
     classNameMap() {
       return {
+        [CONTEXT_LINE_CLASS_NAME]: this.isContextLine,
         [PARALLEL_DIFF_VIEW_TYPE]: true,
       };
     },
diff --git a/app/assets/javascripts/diffs/constants.js b/app/assets/javascripts/diffs/constants.js
index f5f5c0ffc29..78a39baa4cb 100644
--- a/app/assets/javascripts/diffs/constants.js
+++ b/app/assets/javascripts/diffs/constants.js
@@ -3,6 +3,7 @@ export const PARALLEL_DIFF_VIEW_TYPE = 'parallel';
 export const MATCH_LINE_TYPE = 'match';
 export const OLD_NO_NEW_LINE_TYPE = 'old-nonewline';
 export const NEW_NO_NEW_LINE_TYPE = 'new-nonewline';
+export const CONTEXT_LINE_TYPE = 'context';
 export const EMPTY_CELL_TYPE = 'empty-cell';
 export const COMMENT_FORM_TYPE = 'commentForm';
 export const DIFF_NOTE_TYPE = 'DiffNote';
@@ -21,6 +22,7 @@ export const LINE_SIDE_RIGHT = 'right-side';
 export const DIFF_VIEW_COOKIE_NAME = 'diff_view';
 export const LINE_HOVER_CLASS_NAME = 'is-over';
 export const LINE_UNFOLD_CLASS_NAME = 'unfold js-unfold';
+export const CONTEXT_LINE_CLASS_NAME = 'diff-expanded';
 
 export const UNFOLD_COUNT = 20;
 export const COUNT_OF_AVATARS_IN_GUTTER = 3;
diff --git a/app/assets/javascripts/diffs/store/mutations.js b/app/assets/javascripts/diffs/store/mutations.js
index e651c197968..a7eea2c1449 100644
--- a/app/assets/javascripts/diffs/store/mutations.js
+++ b/app/assets/javascripts/diffs/store/mutations.js
@@ -65,13 +65,7 @@ export default {
     const { highlightedDiffLines, parallelDiffLines } = diffFile;
 
     removeMatchLine(diffFile, lineNumbers, bottom);
-
-    const lines = addLineReferences(contextLines, lineNumbers, bottom).map(line => ({
-      ...line,
-      lineCode: line.lineCode || `${fileHash}_${line.oldLine}_${line.newLine}`,
-      discussions: line.discussions || [],
-    }));
-
+    const lines = addLineReferences(contextLines, lineNumbers, bottom);
     addContextLines({
       inlineLines: highlightedDiffLines,
       parallelLines: parallelDiffLines,
diff --git a/app/controllers/projects/blob_controller.rb b/app/controllers/projects/blob_controller.rb
index 2a6fe3b9c97..c02ec407262 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, nil, nil, nil, nil)
+      diff_line = Gitlab::Diff::Line.new(line, 'context', 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 740f41c0642..5307cd0720a 100644
--- a/app/controllers/projects/merge_requests/diffs_controller.rb
+++ b/app/controllers/projects/merge_requests/diffs_controller.rb
@@ -22,12 +22,6 @@ class Projects::MergeRequests::DiffsController < Projects::MergeRequests::Applic
 
   def render_diffs
     @environment = @merge_request.environments_for(current_user).last
-    notes_grouped_by_path = @notes.group_by { |note| note.position.file_path }
-
-    @diffs.diff_files.each do |diff_file|
-      notes = notes_grouped_by_path.fetch(diff_file.file_path, [])
-      notes.each { |note| diff_file.unfold_diff_lines(note.position) }
-    end
 
     @diffs.write_cache
 
diff --git a/app/models/diff_note.rb b/app/models/diff_note.rb
index c32008aa9c7..5f59e4832db 100644
--- a/app/models/diff_note.rb
+++ b/app/models/diff_note.rb
@@ -66,10 +66,6 @@ class DiffNote < Note
     self.original_position.diff_refs == diff_refs
   end
 
-  def discussion_first_note?
-    self == discussion.first_note
-  end
-
   private
 
   def enqueue_diff_file_creation_job
@@ -82,33 +78,26 @@ class DiffNote < Note
   end
 
   def should_create_diff_file?
-    on_text? && note_diff_file.nil? && discussion_first_note?
+    on_text? && note_diff_file.nil? && self == discussion.first_note
   end
 
   def fetch_diff_file
-    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
+    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
   end
 
   def supported?
diff --git a/app/services/merge_requests/reload_diffs_service.rb b/app/services/merge_requests/reload_diffs_service.rb
index c64b2e99b52..b47d8f3f63a 100644
--- a/app/services/merge_requests/reload_diffs_service.rb
+++ b/app/services/merge_requests/reload_diffs_service.rb
@@ -29,6 +29,10 @@ module MergeRequests
 
     # rubocop: disable CodeReuse/ActiveRecord
     def clear_cache(new_diff)
+      # Executing the iteration we cache highlighted diffs for each diff file of
+      # MergeRequestDiff.
+      cacheable_collection(new_diff).write_cache
+
       # Remove cache for all diffs on this MR. Do not use the association on the
       # model, as that will interfere with other actions happening when
       # reloading the diff.
diff --git a/app/services/notes/base_service.rb b/app/services/notes/base_service.rb
deleted file mode 100644
index 431ff6c11c4..00000000000
--- a/app/services/notes/base_service.rb
+++ /dev/null
@@ -1,15 +0,0 @@
-# frozen_string_literal: true
-
-module Notes
-  class BaseService < ::BaseService
-    def clear_noteable_diffs_cache(note)
-      noteable = note.noteable
-
-      if note.is_a?(DiffNote) &&
-          note.discussion_first_note? &&
-          note.position.unfolded_diff?(project.repository)
-        noteable.diffs.clear_cache
-      end
-    end
-  end
-end
diff --git a/app/services/notes/create_service.rb b/app/services/notes/create_service.rb
index e03789e3ca9..049e6c5a871 100644
--- a/app/services/notes/create_service.rb
+++ b/app/services/notes/create_service.rb
@@ -1,7 +1,7 @@
 # frozen_string_literal: true
 
 module Notes
-  class CreateService < ::Notes::BaseService
+  class CreateService < ::BaseService
     def execute
       merge_request_diff_head_sha = params.delete(:merge_request_diff_head_sha)
 
@@ -35,7 +35,6 @@ module Notes
 
       if !only_commands && note.save
         todo_service.new_note(note, current_user)
-        clear_noteable_diffs_cache(note)
       end
 
       if command_params.present?
diff --git a/app/services/notes/destroy_service.rb b/app/services/notes/destroy_service.rb
index fa0c2c5c86b..64e9accd97f 100644
--- a/app/services/notes/destroy_service.rb
+++ b/app/services/notes/destroy_service.rb
@@ -1,13 +1,11 @@
 # frozen_string_literal: true
 
 module Notes
-  class DestroyService < ::Notes::BaseService
+  class DestroyService < BaseService
     def execute(note)
       TodoService.new.destroy_target(note) do |note|
         note.destroy
       end
-
-      clear_noteable_diffs_cache(note)
     end
   end
 end
diff --git a/changelogs/unreleased/osw-comment-on-any-line-on-diffs.yml b/changelogs/unreleased/osw-comment-on-any-line-on-diffs.yml
deleted file mode 100644
index 7b48a94a993..00000000000
--- a/changelogs/unreleased/osw-comment-on-any-line-on-diffs.yml
+++ /dev/null
@@ -1,5 +0,0 @@
----
-title: Allow commenting on any diff line in Merge Requests
-merge_request: 22398
-author:
-type: added
diff --git a/lib/gitlab/diff/file.rb b/lib/gitlab/diff/file.rb
index 84595f8afd7..fb117baca9e 100644
--- a/lib/gitlab/diff/file.rb
+++ b/lib/gitlab/diff/file.rb
@@ -26,7 +26,6 @@ module Gitlab
         @repository = repository
         @diff_refs = diff_refs
         @fallback_diff_refs = fallback_diff_refs
-        @unfolded = false
 
         # Ensure items are collected in the the batch
         new_blob_lazy
@@ -136,24 +135,6 @@ 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
-
-        unfolder = Gitlab::Diff::LinesUnfolder.new(self, position)
-
-        if unfolder.unfold_required?
-          @diff_lines = unfolder.unfolded_diff_lines
-          @unfolded = true
-        end
-      end
-
-      def unfolded?
-        @unfolded
-      end
-
       def highlighted_diff_lines
         @highlighted_diff_lines ||=
           Gitlab::Diff::Highlight.new(self, repository: self.repository).highlight
diff --git a/lib/gitlab/diff/line.rb b/lib/gitlab/diff/line.rb
index 70063071ee7..5b67cd46c48 100644
--- a/lib/gitlab/diff/line.rb
+++ b/lib/gitlab/diff/line.rb
@@ -3,9 +3,9 @@ module Gitlab
     class Line
       SERIALIZE_KEYS = %i(line_code rich_text text type index old_pos new_pos).freeze
 
-      attr_reader :line_code, :type, :old_pos, :new_pos
+      attr_reader :line_code, :type, :index, :old_pos, :new_pos
       attr_writer :rich_text
-      attr_accessor :text, :index
+      attr_accessor :text
 
       def initialize(text, type, index, old_pos, new_pos, parent_file: nil, line_code: nil, rich_text: nil)
         @text, @type, @index = text, type, index
@@ -19,14 +19,7 @@ module Gitlab
       end
 
       def self.init_from_hash(hash)
-        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])
+        new(hash[:text], hash[:type], hash[:index], hash[:old_pos], hash[:new_pos], line_code: hash[:line_code], rich_text: hash[:rich_text])
       end
 
       def to_hash
diff --git a/lib/gitlab/diff/lines_unfolder.rb b/lib/gitlab/diff/lines_unfolder.rb
deleted file mode 100644
index 9306b7e16a2..00000000000
--- a/lib/gitlab/diff/lines_unfolder.rb
+++ /dev/null
@@ -1,235 +0,0 @@
-# frozen_string_literal: true
-
-# Given a position, calculates which Blob lines should be extracted, treated and
-# injected in the current diff file lines in order to present a "unfolded" diff.
-module Gitlab
-  module Diff
-    class LinesUnfolder
-      include Gitlab::Utils::StrongMemoize
-
-      UNFOLD_CONTEXT_SIZE = 3
-
-      def initialize(diff_file, position)
-        @diff_file = diff_file
-        @blob = diff_file.old_blob
-        @position = position
-        @generate_top_match_line = true
-        @generate_bottom_match_line = true
-
-        # These methods update `@generate_top_match_line` and
-        # `@generate_bottom_match_line`.
-        @from_blob_line = calculate_from_blob_line!
-        @to_blob_line = calculate_to_blob_line!
-      end
-
-      # Returns merged diff lines with required blob lines with correct
-      # positions.
-      def unfolded_diff_lines
-        strong_memoize(:unfolded_diff_lines) do
-          next unless unfold_required?
-
-          merged_diff_with_blob_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 lines, unlike diffs, doesn't start with an empty space for
-          # unchanged line, so the parsing and highlighting step can get fuzzy
-          # without the following change.
-          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
-
-      def unfold_required?
-        strong_memoize(:unfold_required) do
-          next false unless @diff_file.text?
-          next false unless @position.unchanged?
-          next false if @diff_file.new_file? || @diff_file.deleted_file?
-          next false unless @position.old_line
-          # Invalid position (MR import scenario)
-          next false if @position.old_line > @blob.lines.size
-          next false if @diff_file.diff_lines.empty?
-          next false if @diff_file.line_for_position(@position)
-          next false unless unfold_line
-
-          true
-        end
-      end
-
-      private
-
-      attr_reader :from_blob_line, :to_blob_line
-
-      def merged_diff_with_blob_lines
-        lines = @diff_file.diff_lines
-        match_line = unfold_line
-        insert_index = bottom? ? -1 : match_line.index
-
-        lines -= [match_line] unless bottom?
-
-        lines.insert(insert_index, *blob_lines_with_matches)
-
-        # 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_matches
-        old_pos = from_blob_line
-        new_pos = from_blob_line + offset
-
-        new_blob_lines = []
-
-        new_blob_lines.push(top_blob_match_line) if top_blob_match_line
-
-        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.push(bottom_blob_match_line) if bottom_blob_match_line
-
-        new_blob_lines
-      end
-
-      def reindex(lines)
-        lines.each_with_index { |line, i| line.index = i }
-      end
-
-      def top_blob_match_line
-        strong_memoize(:top_blob_match_line) do
-          next unless @generate_top_match_line
-
-          old_pos = from_blob_line
-          new_pos = from_blob_line + offset
-
-          build_match_line(old_pos, new_pos)
-        end
-      end
-
-      def bottom_blob_match_line
-        strong_memoize(:bottom_blob_match_line) do
-          # The bottom line match addition is already handled on
-          # Diff::File#diff_lines_for_serializer
-          next if bottom?
-          next unless @generate_bottom_match_line
-
-          position = line_after_unfold_position.old_pos
-
-          old_pos = position
-          new_pos = position + offset
-
-          build_match_line(old_pos, new_pos)
-        end
-      end
-
-      def build_match_line(old_pos, new_pos)
-        blob_lines_length = blob_lines.length
-        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
-
-      # Returns the first line position that should be extracted
-      # from `blob_lines`.
-      def calculate_from_blob_line!
-        return unless unfold_required?
-
-        from = comment_position - UNFOLD_CONTEXT_SIZE
-
-        # There's no line before the match if it's in the top-most
-        # position.
-        prev_line_number = line_before_unfold_position&.old_pos || 0
-
-        if from <= prev_line_number + 1
-          @generate_top_match_line = false
-          from = prev_line_number + 1
-        end
-
-        from
-      end
-
-      # Returns the last line position that should be extracted
-      # from `blob_lines`.
-      def calculate_to_blob_line!
-        return unless unfold_required?
-
-        to = comment_position + UNFOLD_CONTEXT_SIZE
-
-        return to if bottom?
-
-        next_line_number = line_after_unfold_position.old_pos
-
-        if to >= next_line_number - 1
-          @generate_bottom_match_line = false
-          to = next_line_number - 1
-        end
-
-        to
-      end
-
-      def offset
-        unfold_line.new_pos - unfold_line.old_pos
-      end
-
-      def line_before_unfold_position
-        return unless index = unfold_line&.index
-
-        @diff_file.diff_lines[index - 1] if index > 0
-      end
-
-      def line_after_unfold_position
-        return unless index = unfold_line&.index
-
-        @diff_file.diff_lines[index + 1] if index >= 0
-      end
-
-      def bottom?
-        strong_memoize(:bottom) do
-          @position.old_line > last_line.old_pos
-        end
-      end
-
-      # Returns the line which needed to be expanded in order to send a comment
-      # in `@position`.
-      def unfold_line
-        strong_memoize(:unfold_line) do
-          next last_line if bottom?
-
-          @diff_file.diff_lines.find do |line|
-            line.old_pos > comment_position && line.type == 'match'
-          end
-        end
-      end
-
-      def comment_position
-        @position.old_line
-      end
-
-      def last_line
-        @diff_file.diff_lines.last
-      end
-    end
-  end
-end
diff --git a/lib/gitlab/diff/position.rb b/lib/gitlab/diff/position.rb
index 7bfab2d808f..f967494199e 100644
--- a/lib/gitlab/diff/position.rb
+++ b/lib/gitlab/diff/position.rb
@@ -101,10 +101,6 @@ module Gitlab
         @diff_refs ||= DiffRefs.new(base_sha: base_sha, start_sha: start_sha, head_sha: head_sha)
       end
 
-      def unfolded_diff?(repository)
-        diff_file(repository)&.unfolded?
-      end
-
       def diff_file(repository)
         return @diff_file if defined?(@diff_file)
 
@@ -138,13 +134,7 @@ module Gitlab
         return unless diff_refs.complete?
         return unless comparison = diff_refs.compare_in(repository.project)
 
-        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
+        comparison.diffs(diff_options).diff_files.first
       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 5fdf7f1229d..28f7e4634a5 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 be_nil
+            expect(match_line['type']).to eq('context')
           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 be_nil
+            expect(match_line['type']).to eq('context')
           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 51b78d3e7d1..fa148715855 100644
--- a/spec/features/merge_request/user_posts_diff_notes_spec.rb
+++ b/spec/features/merge_request/user_posts_diff_notes_spec.rb
@@ -85,13 +85,12 @@ describe 'Merge request > User posts diff notes', :js do
       # `.line_holder` will be an unfolded line.
       let(:line_holder) { first('#a5cc2925ca8258af241be7e5b0381edf30266302 .line_holder') }
 
-      it 'allows commenting on the left side' do
-        should_allow_commenting(line_holder, 'left')
+      it 'does not allow commenting on the left side' do
+        should_not_allow_commenting(line_holder, 'left')
       end
 
-      it 'allows commenting on the right side' do
-        # Automatically shifts comment box to left side.
-        should_allow_commenting(line_holder, 'right')
+      it 'does not allow commenting on the right side' do
+        should_not_allow_commenting(line_holder, 'right')
       end
     end
   end
@@ -148,8 +147,8 @@ 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 'allows commenting' do
-        should_allow_commenting line_holder
+      it 'does not allow commenting' do
+        should_not_allow_commenting line_holder
       end
     end
 
diff --git a/spec/javascripts/diffs/store/mutations_spec.js b/spec/javascripts/diffs/store/mutations_spec.js
index 8821cde76f4..fed04cbaed8 100644
--- a/spec/javascripts/diffs/store/mutations_spec.js
+++ b/spec/javascripts/diffs/store/mutations_spec.js
@@ -98,7 +98,7 @@ describe('DiffsStoreMutations', () => {
     it('should call utils.addContextLines with proper params', () => {
       const options = {
         lineNumbers: { oldLineNumber: 1, newLineNumber: 2 },
-        contextLines: [{ oldLine: 1, newLine: 1, lineCode: 'ff9200_1_1', discussions: [] }],
+        contextLines: [{ oldLine: 1 }],
         fileHash: 'ff9200',
         params: {
           bottom: true,
@@ -110,7 +110,7 @@ describe('DiffsStoreMutations', () => {
         parallelDiffLines: [],
       };
       const state = { diffFiles: [diffFile] };
-      const lines = [{ oldLine: 1, newLine: 1 }];
+      const lines = [{ oldLine: 1 }];
 
       const findDiffFileSpy = spyOnDependency(mutations, 'findDiffFile').and.returnValue(diffFile);
       const removeMatchLineSpy = spyOnDependency(mutations, 'removeMatchLine');
diff --git a/spec/lib/gitlab/diff/file_spec.rb b/spec/lib/gitlab/diff/file_spec.rb
index 3417896e259..2f51642b58e 100644
--- a/spec/lib/gitlab/diff/file_spec.rb
+++ b/spec/lib/gitlab/diff/file_spec.rb
@@ -41,52 +41,6 @@ describe Gitlab::Diff::File do
     end
   end
 
-  describe '#unfold_diff_lines' do
-    let(:unfolded_lines) { double('expanded-lines') }
-    let(:unfolder) { instance_double(Gitlab::Diff::LinesUnfolder) }
-    let(:position) { instance_double(Gitlab::Diff::Position, old_line: 10) }
-
-    before do
-      allow(Gitlab::Diff::LinesUnfolder).to receive(:new) { unfolder }
-    end
-
-    context 'when unfold required' do
-      before do
-        allow(unfolder).to receive(:unfold_required?) { true }
-        allow(unfolder).to receive(:unfolded_diff_lines) { unfolded_lines }
-      end
-
-      it 'changes @unfolded to true' do
-        diff_file.unfold_diff_lines(position)
-
-        expect(diff_file).to be_unfolded
-      end
-
-      it 'updates @diff_lines' do
-        diff_file.unfold_diff_lines(position)
-
-        expect(diff_file.diff_lines).to eq(unfolded_lines)
-      end
-    end
-
-    context 'when unfold not required' do
-      before do
-        allow(unfolder).to receive(:unfold_required?) { false }
-      end
-
-      it 'keeps @unfolded false' do
-        diff_file.unfold_diff_lines(position)
-
-        expect(diff_file).not_to be_unfolded
-      end
-
-      it 'does not update @diff_lines' do
-        expect { diff_file.unfold_diff_lines(position) }
-          .not_to change(diff_file, :diff_lines)
-      end
-    end
-  end
-
   describe '#mode_changed?' do
     it { expect(diff_file.mode_changed?).to be_falsey }
   end
diff --git a/spec/lib/gitlab/diff/lines_unfolder_spec.rb b/spec/lib/gitlab/diff/lines_unfolder_spec.rb
deleted file mode 100644
index 8e00c8e0e30..00000000000
--- a/spec/lib/gitlab/diff/lines_unfolder_spec.rb
+++ /dev/null
@@ -1,750 +0,0 @@
-# frozen_string_literal: true
-
-require 'spec_helper'
-
-describe Gitlab::Diff::LinesUnfolder do
-  let(:raw_diff) do
-    <<-DIFF.strip_heredoc
-      @@ -7,9 +7,6 @@
-           "tags": ["devel", "development", "nightly"],
-           "desktop-file-name-prefix": "(Development) ",
-           "finish-args": [
-      -        "--share=ipc", "--socket=x11",
-      -        "--socket=wayland",
-      -        "--talk-name=org.gnome.OnlineAccounts",
-               "--talk-name=org.freedesktop.Tracker1",
-               "--filesystem=home",
-               "--talk-name=org.gtk.vfs", "--talk-name=org.gtk.vfs.*",
-      @@ -62,7 +59,7 @@
-               },
-               {
-                   "name": "gnome-desktop",
-      -            "config-opts": ["--disable-debug-tools", "--disable-udev"],
-      +            "config-opts": ["--disable-debug-tools", "--disable-"],
-                   "sources": [
-                       {
-                           "type": "git",
-      @@ -83,11 +80,6 @@
-                   "buildsystem": "meson",
-                   "builddir": true,
-                   "name": "nautilus",
-      -            "config-opts": [
-      -                "-Denable-desktop=false",
-      -                "-Denable-selinux=false",
-      -                "--libdir=/app/lib"
-      -            ],
-                   "sources": [
-                       {
-                           "type": "git",
-    DIFF
-  end
-
-  let(:raw_old_blob) do
-    <<-BLOB.strip_heredoc
-      {
-          "app-id": "org.gnome.Nautilus",
-          "runtime": "org.gnome.Platform",
-          "runtime-version": "master",
-          "sdk": "org.gnome.Sdk",
-          "command": "nautilus",
-          "tags": ["devel", "development", "nightly"],
-          "desktop-file-name-prefix": "(Development) ",
-          "finish-args": [
-              "--share=ipc", "--socket=x11",
-              "--socket=wayland",
-              "--talk-name=org.gnome.OnlineAccounts",
-              "--talk-name=org.freedesktop.Tracker1",
-              "--filesystem=home",
-              "--talk-name=org.gtk.vfs", "--talk-name=org.gtk.vfs.*",
-              "--filesystem=xdg-run/dconf", "--filesystem=~/.config/dconf:ro",
-              "--talk-name=ca.desrt.dconf", "--env=DCONF_USER_CONFIG_DIR=.config/dconf"
-          ],
-          "cleanup": [ "/include", "/share/bash-completion" ],
-          "modules": [
-              {
-                  "name": "exiv2",
-                  "sources": [
-                      {
-                          "type": "archive",
-                          "url": "http://exiv2.org/builds/exiv2-0.26-trunk.tar.gz",
-                          "sha256": "c75e3c4a0811bf700d92c82319373b7a825a2331c12b8b37d41eb58e4f18eafb"
-                      },
-                      {
-                          "type": "shell",
-                          "commands": [
-                              "cp -f /usr/share/gnu-config/config.sub ./config/",
-                              "cp -f /usr/share/gnu-config/config.guess ./config/"
-                          ]
-                      }
-                  ]
-              },
-              {
-                  "name": "gexiv2",
-                  "config-opts": [ "--disable-introspection" ],
-                  "sources": [
-                      {
-                          "type": "git",
-                          "url": "https://git.gnome.org/browse/gexiv2"
-                      }
-                  ]
-              },
-              {
-                  "name": "tracker",
-                  "cleanup": [ "/bin", "/etc", "/libexec" ],
-                  "config-opts": [ "--disable-miner-apps", "--disable-static",
-                                   "--disable-tracker-extract", "--disable-tracker-needle",
-                                   "--disable-tracker-preferences", "--disable-artwork",
-                                   "--disable-tracker-writeback", "--disable-miner-user-guides",
-                                   "--with-bash-completion-dir=no" ],
-                  "sources": [
-                      {
-                          "type": "git",
-                          "url": "https://git.gnome.org/browse/tracker"
-                      }
-                  ]
-              },
-              {
-                  "name": "gnome-desktop",
-                  "config-opts": ["--disable-debug-tools", "--disable-udev"],
-                  "sources": [
-                      {
-                          "type": "git",
-                          "url": "https://git.gnome.org/browse/gnome-desktop"
-                      }
-                  ]
-              },
-              {
-                  "name": "gnome-autoar",
-                  "sources": [
-                      {
-                          "type": "git",
-                          "url": "https://git.gnome.org/browse/gnome-autoar"
-                      }
-                  ]
-              },
-              {
-                  "buildsystem": "meson",
-                  "builddir": true,
-                  "name": "nautilus",
-                  "config-opts": [
-                      "-Denable-desktop=false",
-                      "-Denable-selinux=false",
-                      "--libdir=/app/lib"
-                  ],
-                  "sources": [
-                      {
-                          "type": "git",
-                          "url": "https://gitlab.gnome.org/GNOME/nautilus.git"
-                      }
-                  ]
-              }
-          ]
-      },
-      {
-          "app-id": "foo",
-          "runtime": "foo",
-          "runtime-version": "foo",
-          "sdk": "foo",
-          "command": "foo",
-          "tags": ["foo", "bar", "kux"],
-          "desktop-file-name-prefix": "(Foo) ",
-          {
-            "buildsystem": "meson",
-            "builddir": true,
-            "name": "nautilus",
-            "sources": [
-              {
-                "type": "git",
-                "url": "https://gitlab.gnome.org/GNOME/nautilus.git"
-              }
-            ]
-          }
-      },
-      {
-          "app-id": "foo",
-          "runtime": "foo",
-          "runtime-version": "foo",
-          "sdk": "foo",
-          "command": "foo",
-          "tags": ["foo", "bar", "kux"],
-          "desktop-file-name-prefix": "(Foo) ",
-          {
-            "buildsystem": "meson",
-            "builddir": true,
-            "name": "nautilus",
-            "sources": [
-              {
-                "type": "git",
-                "url": "https://gitlab.gnome.org/GNOME/nautilus.git"
-              }
-            ]
-          }
-      }
-    BLOB
-  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 middle expansion and new match lines' 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
-        [[40, 40, "             \"config-opts\": [ \"--disable-introspection\" ],"],
-         [41, 41, "             \"sources\": ["],
-         [42, 42, "                 {"],
-         [43, 43, "                     \"type\": \"git\","],
-         [44, 44, "                     \"url\": \"https://git.gnome.org/browse/gexiv2\""],
-         [45, 45, "                 }"],
-         [46, 46, "             ]"]]
-      end
-
-      it 'returns the extracted blob lines correctly' do
-        extracted_lines = subject.blob_lines
-
-        expect(extracted_lines.size).to eq(7)
-
-        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
-         [40, 37, "@@ -40,7+37,7 @@"],
-
-         # Injected blob lines
-         [40, 37, "             \"config-opts\": [ \"--disable-introspection\" ],"],
-         [41, 38, "             \"sources\": ["],
-         [42, 39, "                 {"],
-         [43, 40, "                     \"type\": \"git\","], # comment
-         [44, 41, "                     \"url\": \"https://git.gnome.org/browse/gexiv2\""],
-         [45, 42, "                 }"],
-         [46, 43, "             ]"],
-         # end
-
-         # Second match line
-         [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.unfolded_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.unfolded_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 middle expansion and no top match line' 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: 16,
-                                 new_line: 17)
-    end
-
-    context 'blob lines' do
-      let(:expected_blob_lines) do
-        [[16, 16, "         \"--filesystem=xdg-run/dconf\", \"--filesystem=~/.config/dconf:ro\","],
-         [17, 17, "         \"--talk-name=ca.desrt.dconf\", \"--env=DCONF_USER_CONFIG_DIR=.config/dconf\""],
-         [18, 18, "     ],"],
-         [19, 19, "     \"cleanup\": [ \"/include\", \"/share/bash-completion\" ],"]]
-      end
-
-      it 'returns the extracted blob lines correctly' do
-        extracted_lines = subject.blob_lines
-
-        expect(extracted_lines.size).to eq(4)
-
-        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.*\","],
-         # No new match needed
-
-         # Injected blob lines
-         [16, 13, "         \"--filesystem=xdg-run/dconf\", \"--filesystem=~/.config/dconf:ro\","],
-         [17, 14, "         \"--talk-name=ca.desrt.dconf\", \"--env=DCONF_USER_CONFIG_DIR=.config/dconf\""],
-         [18, 15, "     ],"],
-         [19, 16, "     \"cleanup\": [ \"/include\", \"/share/bash-completion\" ],"],
-         # end
-
-         # Second match line
-         [62, 59, "@@ -62,4+59,4 @@"],
-
-         [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.unfolded_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.unfolded_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 middle expansion and no bottom match line' 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: 82,
-                                 new_line: 79)
-    end
-
-    context 'blob lines' do
-      let(:expected_blob_lines) do
-        [[79, 79, "                 }"],
-         [80, 80, "             ]"],
-         [81, 81, "         },"],
-         [82, 82, "         {"]]
-      end
-
-      it 'returns the extracted blob lines correctly' do
-        extracted_lines = subject.blob_lines
-
-        expect(extracted_lines.size).to eq(4)
-
-        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\","],
-
-         # New top match line
-         [79, 76, "@@ -79,4+76,4 @@"],
-
-         # Injected blob lines
-         [79, 76, "                 }"],
-         [80, 77, "             ]"],
-         [81, 78, "         },"],
-         [82, 79, "         {"],
-         # end
-
-         # No new second match line
-         [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.unfolded_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.unfolded_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: 6,
-                                 new_line: 6)
-    end
-
-    context 'blob lines' do
-      let(:expected_blob_lines) do
-        [[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(4)
-
-        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
-        # New match line
-        [[3, 3, "@@ -3,4+3,4 @@"],
-
-         # Injected blob lines
-         [3, 3, "     \"runtime\": \"org.gnome.Platform\","],
-         [4, 4, "     \"runtime-version\": \"master\","],
-         [5, 5, "     \"sdk\": \"org.gnome.Sdk\","],
-         [6, 6, "     \"command\": \"nautilus\","],
-         # end
-         [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.unfolded_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.unfolded_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
-      it 'returns nil' do
-        expect(subject.unfolded_diff_lines).to be_nil
-      end
-    end
-  end
-
-  context 'position requires bottom expansion and new match lines' 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: 107,
-                                 new_line: 99)
-    end
-
-    context 'blob lines' do
-      let(:expected_blob_lines) do
-        [[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,"]]
-      end
-
-      it 'returns the extracted blob lines correctly' do
-        extracted_lines = subject.blob_lines
-
-        expect(extracted_lines.size).to eq(7)
-
-        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\","],
-         # New match line
-         [104, 96, "@@ -104,7+96,7 @@"],
-
-         # Injected blob lines
-         [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,"]]
-        # end
-      end
-
-      it 'return merge of blob lines with diff lines correctly' do
-        new_diff_lines = subject.unfolded_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.unfolded_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
diff --git a/spec/services/merge_requests/reload_diffs_service_spec.rb b/spec/services/merge_requests/reload_diffs_service_spec.rb
index 5acd01828cb..546c9f277c5 100644
--- a/spec/services/merge_requests/reload_diffs_service_spec.rb
+++ b/spec/services/merge_requests/reload_diffs_service_spec.rb
@@ -31,11 +31,32 @@ describe MergeRequests::ReloadDiffsService, :use_clean_rails_memory_store_cachin
     end
 
     context 'cache clearing' do
+      before do
+        allow_any_instance_of(Gitlab::Diff::File).to receive(:text?).and_return(true)
+        allow_any_instance_of(Gitlab::Diff::File).to receive(:diffable?).and_return(true)
+      end
+
+      it 'retrieves the diff files to cache the highlighted result' do
+        new_diff = merge_request.create_merge_request_diff
+        cache_key = new_diff.diffs_collection.cache_key
+
+        expect(merge_request).to receive(:create_merge_request_diff).and_return(new_diff)
+        expect(Rails.cache).to receive(:read).with(cache_key).and_call_original
+        expect(Rails.cache).to receive(:write).with(cache_key, anything, anything).and_call_original
+
+        subject.execute
+      end
+
       it 'clears the cache for older diffs on the merge request' do
         old_diff = merge_request.merge_request_diff
         old_cache_key = old_diff.diffs_collection.cache_key
+        new_diff = merge_request.create_merge_request_diff
+        new_cache_key = new_diff.diffs_collection.cache_key
 
+        expect(merge_request).to receive(:create_merge_request_diff).and_return(new_diff)
         expect(Rails.cache).to receive(:delete).with(old_cache_key).and_call_original
+        expect(Rails.cache).to receive(:read).with(new_cache_key).and_call_original
+        expect(Rails.cache).to receive(:write).with(new_cache_key, anything, anything).and_call_original
 
         subject.execute
       end
diff --git a/spec/services/notes/create_service_spec.rb b/spec/services/notes/create_service_spec.rb
index 80b015d4cd0..b1290fd0d47 100644
--- a/spec/services/notes/create_service_spec.rb
+++ b/spec/services/notes/create_service_spec.rb
@@ -57,57 +57,6 @@ describe Notes::CreateService do
       end
     end
 
-    context 'noteable highlight cache clearing' do
-      let(:project_with_repo) { create(:project, :repository) }
-      let(:merge_request) do
-        create(:merge_request, source_project: project_with_repo,
-                               target_project: project_with_repo)
-      end
-
-      let(:position) do
-        Gitlab::Diff::Position.new(old_path: "files/ruby/popen.rb",
-                                   new_path: "files/ruby/popen.rb",
-                                   old_line: nil,
-                                   new_line: 14,
-                                   diff_refs: merge_request.diff_refs)
-      end
-
-      let(:new_opts) do
-        opts.merge(in_reply_to_discussion_id: nil,
-                   type: 'DiffNote',
-                   noteable_type: 'MergeRequest',
-                   noteable_id: merge_request.id,
-                   position: position.to_h)
-      end
-
-      before do
-        allow_any_instance_of(Gitlab::Diff::Position)
-          .to receive(:unfolded_diff?) { true }
-      end
-
-      it 'clears noteable diff cache when it was unfolded for the note position' do
-        expect_any_instance_of(Gitlab::Diff::HighlightCache).to receive(:clear)
-
-        described_class.new(project_with_repo, user, new_opts).execute
-      end
-
-      it 'does not clear cache when note is not the first of the discussion' do
-        prev_note =
-          create(:diff_note_on_merge_request, noteable: merge_request,
-                                              project: project_with_repo)
-        reply_opts =
-          opts.merge(in_reply_to_discussion_id: prev_note.discussion_id,
-                     type: 'DiffNote',
-                     noteable_type: 'MergeRequest',
-                     noteable_id: merge_request.id,
-                     position: position.to_h)
-
-        expect(merge_request).not_to receive(:diffs)
-
-        described_class.new(project_with_repo, user, reply_opts).execute
-      end
-    end
-
     context 'note diff file' do
       let(:project_with_repo) { create(:project, :repository) }
       let(:merge_request) do
diff --git a/spec/services/notes/destroy_service_spec.rb b/spec/services/notes/destroy_service_spec.rb
index b1f4e87e8ea..64445be560e 100644
--- a/spec/services/notes/destroy_service_spec.rb
+++ b/spec/services/notes/destroy_service_spec.rb
@@ -21,38 +21,5 @@ describe Notes::DestroyService do
       expect { described_class.new(project, user).execute(note) }
         .to change { user.todos_pending_count }.from(1).to(0)
     end
-
-    context 'noteable highlight cache clearing' do
-      let(:repo_project) { create(:project, :repository) }
-      let(:merge_request) do
-        create(:merge_request, source_project: repo_project,
-                               target_project: repo_project)
-      end
-
-      let(:note) do
-        create(:diff_note_on_merge_request, project: repo_project,
-                                            noteable: merge_request)
-      end
-
-      before do
-        allow(note.position).to receive(:unfolded_diff?) { true }
-      end
-
-      it 'clears noteable diff cache when it was unfolded for the note position' do
-        expect(merge_request).to receive_message_chain(:diffs, :clear_cache)
-
-        described_class.new(repo_project, user).execute(note)
-      end
-
-      it 'does not clear cache when note is not the first of the discussion' do
-        reply_note = create(:diff_note_on_merge_request, in_reply_to: note,
-                                                         project: repo_project,
-                                                         noteable: merge_request)
-
-        expect(merge_request).not_to receive(:diffs)
-
-        described_class.new(repo_project, user).execute(reply_note)
-      end
-    end
   end
 end