Don't display comment on unchanged line on both sides in parallel diffdm-parallel-diff-unchanged-line-comment

5 files changed, 29 insertions, 24 deletions

diff --git a/app/helpers/diff_helper.rb b/app/helpers/diff_helper.rb
index 06822747d11..0dc08cab166 100644
--- a/app/helpers/diff_helper.rb
+++ b/app/helpers/diff_helper.rb
@@ -66,12 +66,12 @@ module DiffHelper
 
     discussions_left = discussions_right = nil
 
-    if left && (left.unchanged? || left.discussable?)
+    if left&.unchanged? || left&.removed? && !left&.meta?
       line_code = diff_file.line_code(left)
       discussions_left = @grouped_diff_discussions[line_code]
     end
 
-    if right&.discussable?
+    if right&.added? && !right&.meta?
       line_code = diff_file.line_code(right)
       discussions_right = @grouped_diff_discussions[line_code]
     end
diff --git a/app/views/projects/diffs/_line.html.haml b/app/views/projects/diffs/_line.html.haml
index 43708d22a0c..7439b8a66f7 100644
--- a/app/views/projects/diffs/_line.html.haml
+++ b/app/views/projects/diffs/_line.html.haml
@@ -3,7 +3,7 @@
 - discussions = local_assigns.fetch(:discussions, nil)
 - type = line.type
 - line_code = diff_file.line_code(line)
-- if discussions && line.discussable?
+- if discussions && !line.meta?
   - line_discussions = discussions[line_code]
 %tr.line_holder{ class: type, id: (line_code unless plain) }
   - case type
diff --git a/lib/gitlab/diff/line.rb b/lib/gitlab/diff/line.rb
index bd52ae47e9f..e89f7069219 100644
--- a/lib/gitlab/diff/line.rb
+++ b/lib/gitlab/diff/line.rb
@@ -42,11 +42,15 @@ module Gitlab
       end
 
       def added?
-        type == 'new' || type == 'new-nonewline'
+        %w[new new-nonewline].include?(type)
       end
 
       def removed?
-        type == 'old' || type == 'old-nonewline'
+        %w[old old-nonewline].include?(type)
+      end
+
+      def meta?
+        %w[match new-nonewline old-nonewline].include?(type)
       end
 
       def rich_text
@@ -55,14 +59,6 @@ module Gitlab
         @rich_text
       end
 
-      def meta?
-        type == 'match'
-      end
-
-      def discussable?
-        !['match', 'new-nonewline', 'old-nonewline'].include?(type)
-      end
-
       def as_json(opts = nil)
         {
           type: type,
diff --git a/lib/gitlab/diff/parallel_diff.rb b/lib/gitlab/diff/parallel_diff.rb
index 481536a380b..0cb26fa45c8 100644
--- a/lib/gitlab/diff/parallel_diff.rb
+++ b/lib/gitlab/diff/parallel_diff.rb
@@ -14,16 +14,7 @@ module Gitlab
         lines = []
         highlighted_diff_lines = diff_file.highlighted_diff_lines
         highlighted_diff_lines.each do |line|
-          if line.meta? || line.unchanged?
-            # line in the right panel is the same as in the left one
-            lines << {
-              left: line,
-              right: line
-            }
-
-            free_right_index = nil
-            i += 1
-          elsif line.removed?
+          if line.removed?
             lines << {
               left: line,
               right: nil
@@ -51,6 +42,15 @@ module Gitlab
               free_right_index = nil
               i += 1
             end
+          elsif line.meta? || line.unchanged?
+            # line in the right panel is the same as in the left one
+            lines << {
+              left: line,
+              right: line
+            }
+
+            free_right_index = nil
+            i += 1
           end
         end
 
diff --git a/spec/helpers/diff_helper_spec.rb b/spec/helpers/diff_helper_spec.rb
index 0ac030d3171..0d909e6e140 100644
--- a/spec/helpers/diff_helper_spec.rb
+++ b/spec/helpers/diff_helper_spec.rb
@@ -148,12 +148,21 @@ describe DiffHelper do
 
     it 'puts comments on added lines' do
       left = Gitlab::Diff::Line.new('\\nonewline', 'old-nonewline', 3, 3, 3)
-      right = Gitlab::Diff::Line.new('new line', 'add', 3, 3, 3)
+      right = Gitlab::Diff::Line.new('new line', 'new', 3, 3, 3)
 
       result = helper.parallel_diff_discussions(left, right, diff_file)
 
       expect(result).to eq([nil, 'comment'])
     end
+
+    it 'puts comments on unchanged lines' do
+      left = Gitlab::Diff::Line.new('unchanged line', nil, 3, 3, 3)
+      right = Gitlab::Diff::Line.new('unchanged line', nil, 3, 3, 3)
+
+      result = helper.parallel_diff_discussions(left, right, diff_file)
+
+      expect(result).to eq(['comment', nil])
+    end
   end
 
   describe "#diff_match_line" do