Merge branch '21211-comment-on-diff-partially-broken-after-updating-to-8-11' into 'master'

Fix diff comments on legacy MRs

Allow diff commenting on MRs without complete diff refs. (Commenting would work before, but the JSON response would fail, so you'd only see your comment after a refresh.)

Is this really all I needed to do? I feel like there must be more to it :blush:

It's a regression!

Closes #21211.

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- Tests
  - [x] Added for this feature/bug
  - [x] All builds are passing
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [x] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

See merge request !6029
Conflicts:
	spec/features/merge_requests/diff_notes_spec.rb

4 files changed, 298 insertions, 4 deletions

diff --git a/CHANGELOG b/CHANGELOG
index bb407b04b32..f0a64739392 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,6 +1,62 @@
 Please view this file on the master branch, on stable branches it's out of date.
 
 v 8.11.3
+v 8.12.0 (unreleased)
+  - Make push events have equal vertical spacing.
+  - Add two-factor recovery endpoint to internal API !5510
+  - Remove vendor prefixes for linear-gradient CSS (ClemMakesApps)
+  - Add font color contrast to external label in admin area (ClemMakesApps)
+  - Change logo animation to CSS (ClemMakesApps)
+  - Change merge_error column from string to text type
+  - Reduce contributions calendar data payload (ClemMakesApps)
+  - Add `web_url` field to issue, merge request, and snippet API objects (Ben Boeckel)
+  - Set path for all JavaScript cookies to honor GitLab's subdirectory setting !5627 (Mike Greiling)
+  - Add hover color to emoji icon (ClemMakesApps)
+  - Fix branches page dropdown sort alignment (ClemMakesApps)
+  - Add white background for no readme container (ClemMakesApps)
+  - Optimistic locking for Issues and Merge Requests (title and description overriding prevention)
+  - Add `wiki_page_events` to project hook APIs (Ben Boeckel)
+  - Remove Gitorious import
+  - Add Sentry logging to API calls
+  - Automatically expand hidden discussions when accessed by a permalink !5585 (Mike Greiling)
+  - Remove unused mixins (ClemMakesApps)
+  - Fix groups sort dropdown alignment (ClemMakesApps)
+  - Add horizontal scrolling to all sub-navs on mobile viewports (ClemMakesApps)
+  - Fix markdown help references (ClemMakesApps)
+  - Added tests for diff notes
+  - Add delimiter to project stars and forks count (ClemMakesApps)
+  - Fix badge count alignment (ClemMakesApps)
+  - Fix branch title trailing space on hover (ClemMakesApps)
+  - Award emoji tooltips containing more than 10 usernames are now truncated !4780 (jlogandavison)
+  - Fix duplicate "me" in award emoji tooltip !5218 (jlogandavison)
+  - Fix spacing and vertical alignment on build status icon on commits page (ClemMakesApps)
+  - Update merge_requests.md with a simpler way to check out a merge request. !5944
+  - Fix button missing type (ClemMakesApps)
+  - Move to project dropdown with infinite scroll for better performance
+  - Fix leaking of submit buttons outside the width of a main container !18731 (originally by @pavelloz)
+  - Load branches asynchronously in Cherry Pick and Revert dialogs.
+  - Add merge request versions !5467
+  - Change using size to use count and caching it for number of group members. !5935
+  - Added 'only_allow_merge_if_build_succeeds' project setting in the API. !5930 (Duck)
+  - Reduce number of database queries on builds tab
+  - Capitalize mentioned issue timeline notes (ClemMakesApps)
+  - Use the default branch for displaying the project icon instead of master !5792 (Hannes Rosenögger)
+  - Adds response mime type to transaction metric action when it's not HTML
+  - Fix hover leading space bug in pipeline graph !5980
+
+v 8.11.4 (unreleased)
+  - Fix broken gitlab:backup:restore because of bad permissions on repo storage !6098 (Dirk Hörner)
+
+v 8.11.4 (unreleased)
+  - Fix resolving conflicts on forks
+
+v 8.11.4 (unreleased)
+  - Fix diff commenting on merge requests created prior to 8.10
+
+v 8.11.3 (unreleased)
+  - Do not enforce using hash with hidden key in CI configuration. !6079
+  - Allow system info page to handle case where info is unavailable
+  - Label list shows all issues (opened or closed) with that label
   - Don't show resolve conflicts link before MR status is updated
   - Fix IE11 fork button bug !598
   - Don't prevent viewing the MR when git refs for conflicts can't be found on disk
diff --git a/app/models/concerns/note_on_diff.rb b/app/models/concerns/note_on_diff.rb
index a881fb83b7f..b8dd27a7afe 100644
--- a/app/models/concerns/note_on_diff.rb
+++ b/app/models/concerns/note_on_diff.rb
@@ -28,4 +28,8 @@ module NoteOnDiff
   def can_be_award_emoji?
     false
   end
+
+  def to_discussion
+    Discussion.new([self])
+  end
 end
diff --git a/app/models/diff_note.rb b/app/models/diff_note.rb
index c8320ff87fa..4442cefc7e9 100644
--- a/app/models/diff_note.rb
+++ b/app/models/diff_note.rb
@@ -107,10 +107,6 @@ class DiffNote < Note
     self.noteable.find_diff_discussion(self.discussion_id)
   end
 
-  def to_discussion
-    Discussion.new([self])
-  end
-
   private
 
   def supported?
diff --git a/spec/features/merge_requests/diff_notes_spec.rb b/spec/features/merge_requests/diff_notes_spec.rb
new file mode 100644
index 00000000000..06fad1007e8
--- /dev/null
+++ b/spec/features/merge_requests/diff_notes_spec.rb
@@ -0,0 +1,238 @@
+require 'spec_helper'
+
+feature 'Diff notes', js: true, feature: true do
+  include WaitForAjax
+
+  before do
+    login_as :admin
+    @merge_request = create(:merge_request)
+    @project = @merge_request.source_project
+  end
+
+  context 'merge request diffs' do
+    let(:comment_button_class) { '.add-diff-note' }
+    let(:notes_holder_input_class) { 'js-temp-notes-holder' }
+    let(:notes_holder_input_xpath) { './following-sibling::*[contains(concat(" ", @class, " "), " notes_holder ")]' }
+    let(:test_note_comment) { 'this is a test note!' }
+
+    context 'when hovering over a parallel view diff file' do
+      before(:each) do
+        visit diffs_namespace_project_merge_request_path(@project.namespace, @project, @merge_request, view: 'parallel')
+      end
+
+      context 'with an old line on the left and no line on the right' do
+        it 'should allow commenting on the left side' do
+          should_allow_commenting(find('[id="6eb14e00385d2fb284765eb1cd8d420d33d63fc9_23_22"]').find(:xpath, '..'), 'left')
+        end
+
+        it 'should not allow commenting on the right side' do
+          should_not_allow_commenting(find('[id="6eb14e00385d2fb284765eb1cd8d420d33d63fc9_23_22"]').find(:xpath, '..'), 'right')
+        end
+      end
+
+      context 'with no line on the left and a new line on the right' do
+        it 'should not allow commenting on the left side' do
+          should_not_allow_commenting(find('[id="2f6fcd96b88b36ce98c38da085c795a27d92a3dd_15_15"]').find(:xpath, '..'), 'left')
+        end
+
+        it 'should allow commenting on the right side' do
+          should_allow_commenting(find('[id="2f6fcd96b88b36ce98c38da085c795a27d92a3dd_15_15"]').find(:xpath, '..'), 'right')
+        end
+      end
+
+      context 'with an old line on the left and a new line on the right' do
+        it 'should allow commenting on the left side' do
+          should_allow_commenting(find('[id="2f6fcd96b88b36ce98c38da085c795a27d92a3dd_9_9"]').find(:xpath, '..'), 'left')
+        end
+
+        it 'should allow commenting on the right side' do
+          should_allow_commenting(find('[id="2f6fcd96b88b36ce98c38da085c795a27d92a3dd_9_9"]').find(:xpath, '..'), 'right')
+        end
+      end
+
+      context 'with an unchanged line on the left and an unchanged line on the right' do
+        it 'should allow commenting on the left side' do
+          should_allow_commenting(find('[id="2f6fcd96b88b36ce98c38da085c795a27d92a3dd_7_7"]', match: :first).find(:xpath, '..'), 'left')
+        end
+
+        it 'should allow commenting on the right side' do
+          should_allow_commenting(find('[id="2f6fcd96b88b36ce98c38da085c795a27d92a3dd_7_7"]', match: :first).find(:xpath, '..'), 'right')
+        end
+      end
+
+      context 'with a match line' do
+        it 'should not allow commenting on the left side' do
+          should_not_allow_commenting(find('.match', match: :first).find(:xpath, '..'), 'left')
+        end
+
+        it 'should not allow commenting on the right side' do
+          should_not_allow_commenting(find('.match', match: :first).find(:xpath, '..'), 'right')
+        end
+      end
+
+      context 'with an unfolded line' do
+        before(:each) do
+          find('.js-unfold', match: :first).click
+          wait_for_ajax
+        end
+
+        # The first `.js-unfold` unfolds upwards, therefore the first
+        # `.line_holder` will be an unfolded line.
+        let(:line_holder) { first('.line_holder[id="1"]') }
+
+        it 'should not allow commenting on the left side' do
+          should_not_allow_commenting(line_holder, 'left')
+        end
+
+        it 'should not allow commenting on the right side' do
+          should_not_allow_commenting(line_holder, 'right')
+        end
+      end
+    end
+
+    context 'when hovering over an inline view diff file' do
+      before do
+        visit diffs_namespace_project_merge_request_path(@project.namespace, @project, @merge_request, view: 'inline')
+      end
+
+      context 'with a new line' do
+        it 'should allow commenting' do
+          should_allow_commenting(find('[id="2f6fcd96b88b36ce98c38da085c795a27d92a3dd_10_9"]'))
+        end
+      end
+
+      context 'with an old line' do
+        it 'should allow commenting' do
+          should_allow_commenting(find('[id="6eb14e00385d2fb284765eb1cd8d420d33d63fc9_22_22"]'))
+        end
+      end
+
+      context 'with an unchanged line' do
+        it 'should allow commenting' do
+          should_allow_commenting(find('[id="2f6fcd96b88b36ce98c38da085c795a27d92a3dd_7_7"]'))
+        end
+      end
+
+      context 'with a match line' do
+        it 'should not allow commenting' do
+          should_not_allow_commenting(find('.match', match: :first))
+        end
+      end
+
+      context 'with an unfolded line' do
+        before(:each) do
+          find('.js-unfold', match: :first).click
+          wait_for_ajax
+        end
+
+        # The first `.js-unfold` unfolds upwards, therefore the first
+        # `.line_holder` will be an unfolded line.
+        let(:line_holder) { first('.line_holder[id="1"]') }
+
+        it 'should not allow commenting' do
+          should_not_allow_commenting line_holder
+        end
+      end
+
+      context 'when hovering over a diff discussion' do
+        before do
+          visit diffs_namespace_project_merge_request_path(@project.namespace, @project, @merge_request, view: 'inline')
+          should_allow_commenting(find('[id="2f6fcd96b88b36ce98c38da085c795a27d92a3dd_7_7"]'))
+          visit namespace_project_merge_request_path(@project.namespace, @project, @merge_request)
+        end
+
+        it 'should not allow commenting' do
+          should_not_allow_commenting(find('.line_holder', match: :first))
+        end
+      end
+    end
+
+    context 'when the MR only supports legacy diff notes' do
+      before do
+        @merge_request.merge_request_diff.update_attributes(start_commit_sha: nil)
+        visit diffs_namespace_project_merge_request_path(@project.namespace, @project, @merge_request, view: 'inline')
+      end
+
+      context 'with a new line' do
+        it 'should allow commenting' do
+          should_allow_commenting(find('[id="2f6fcd96b88b36ce98c38da085c795a27d92a3dd_10_9"]'))
+        end
+      end
+
+      context 'with an old line' do
+        it 'should allow commenting' do
+          should_allow_commenting(find('[id="6eb14e00385d2fb284765eb1cd8d420d33d63fc9_22_22"]'))
+        end
+      end
+
+      context 'with an unchanged line' do
+        it 'should allow commenting' do
+          should_allow_commenting(find('[id="2f6fcd96b88b36ce98c38da085c795a27d92a3dd_7_7"]'))
+        end
+      end
+
+      context 'with a match line' do
+        it 'should not allow commenting' do
+          should_not_allow_commenting(find('.match', match: :first))
+        end
+      end
+    end
+
+    def should_allow_commenting(line_holder, diff_side = nil)
+      line = get_line_components(line_holder, diff_side)
+      line[:content].hover
+      expect(line[:num]).to have_css comment_button_class
+
+      comment_on_line(line_holder, line)
+
+      assert_comment_persistence(line_holder)
+    end
+
+    def should_not_allow_commenting(line_holder, diff_side = nil)
+      line = get_line_components(line_holder, diff_side)
+      line[:content].hover
+      expect(line[:num]).not_to have_css comment_button_class
+    end
+
+    def get_line_components(line_holder, diff_side = nil)
+      if diff_side.nil?
+        get_inline_line_components(line_holder)
+      else
+        get_parallel_line_components(line_holder, diff_side)
+      end
+    end
+
+    def get_inline_line_components(line_holder)
+      { content: line_holder.find('.line_content', match: :first), num: line_holder.find('.diff-line-num', match: :first) }
+    end
+
+    def get_parallel_line_components(line_holder, diff_side = nil)
+      side_index = diff_side == 'left' ? 0 : 1
+      # Wait for `.line_content`
+      line_holder.find('.line_content', match: :first)
+      # Wait for `.diff-line-num`
+      line_holder.find('.diff-line-num', match: :first)
+      { content: line_holder.all('.line_content')[side_index], num: line_holder.all('.diff-line-num')[side_index] }
+    end
+
+    def comment_on_line(line_holder, line)
+      line[:num].find(comment_button_class).trigger 'click'
+      line_holder.find(:xpath, notes_holder_input_xpath)
+
+      notes_holder_input = line_holder.find(:xpath, notes_holder_input_xpath)
+      expect(notes_holder_input[:class]).to include(notes_holder_input_class)
+
+      notes_holder_input.fill_in 'note[note]', with: test_note_comment
+      click_button 'Comment'
+      wait_for_ajax
+    end
+
+    def assert_comment_persistence(line_holder)
+      expect(line_holder).to have_xpath notes_holder_input_xpath
+
+      notes_holder_saved = line_holder.find(:xpath, notes_holder_input_xpath)
+      expect(notes_holder_saved[:class]).not_to include(notes_holder_input_class)
+      expect(notes_holder_saved).to have_content test_note_comment
+    end
+  end
+end