Merge branch 'tests-for-diff-notes' into 'master'

Tests for diff notes (without failures 🙏)

## What does this MR do?

Adds specs for diff notes.

## Are there points in the code the reviewer needs to double check?

We need to ensure that this doesn't break master again.

## Why was this MR needed?

## What are the relevant issue numbers?
Closes #20957
## Screenshots (if relevant)

## Does this MR meet the acceptance criteria?

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

See merge request !5864

spec/features/merge_requests/diff_notes_spec.rb

+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 the 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
+    end
+
+    context 'when hovering over the 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
+    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