Fix issue comment submit button disabled on GFM paste40373-fix-issue-note-submit-disabled-on-paste

Fix https://gitlab.com/gitlab-org/gitlab-ce/issues/40373

When copying some text from another note and paste,
it goes through `copy_as_gfm` `paste` handler
that calls `e.preventDefault()` which stops things.
But then when inserting the text, we manually trigger
an `input` event with jQuery which doesn't seem to be
picked up by Vue `v-model`.

Using copy/paste trick from https://stackoverflow.com/a/41046276/796832

3 files changed, 35 insertions, 1 deletions

diff --git a/app/assets/javascripts/lib/utils/common_utils.js b/app/assets/javascripts/lib/utils/common_utils.js
index 195e2ca6a78..116b5364fb4 100644
--- a/app/assets/javascripts/lib/utils/common_utils.js
+++ b/app/assets/javascripts/lib/utils/common_utils.js
@@ -190,7 +190,7 @@ export const insertText = (target, text) => {
   target.selectionStart = target.selectionEnd = selectionStart + insertedText.length;
 
   // Trigger autosave
-  $(target).trigger('input');
+  target.dispatchEvent(new Event('input'));
 
   // Trigger autosize
   const event = document.createEvent('Event');
diff --git a/changelogs/unreleased/40373-fix-issue-note-submit-disabled-on-paste.yml b/changelogs/unreleased/40373-fix-issue-note-submit-disabled-on-paste.yml
new file mode 100644
index 00000000000..e683e60397e
--- /dev/null
+++ b/changelogs/unreleased/40373-fix-issue-note-submit-disabled-on-paste.yml
@@ -0,0 +1,6 @@
+---
+title: Fix Issue comment submit button being disabled when pasting content from another
+  GFM note
+merge_request: 15530
+author:
+type: fixed
diff --git a/spec/features/issues/notes_on_issues_spec.rb b/spec/features/issues/notes_on_issues_spec.rb
index 05c93a19253..fbe260a017e 100644
--- a/spec/features/issues/notes_on_issues_spec.rb
+++ b/spec/features/issues/notes_on_issues_spec.rb
@@ -74,4 +74,32 @@ describe 'Create notes on issues', :js do
       let(:mention) { create(:merge_request, source_project: project) }
     end
   end
+
+  describe 'copy GFM note and paste into new comment textarea' do
+    let(:project) { create(:project, :public) }
+    let(:note_text) { 'I **got** this!' }
+    let(:issue) { create(:issue, project: project) }
+
+    before do
+      project.team << [user, :developer]
+      sign_in(user)
+      create(:note, noteable: issue, project: project, note: note_text)
+      visit project_issue_path(project, issue)
+      wait_for_requests
+    end
+
+    it 'can submit comment' do
+      select_element('.note-text')
+      # Copy, [:control, 'c'] and [:command, 'c'] don't work
+      find('body').native.send_keys [:control, :insert]
+
+      find('.js-main-target-form .js-vue-comment-form').click
+      # Paste, [:control, 'v'] and [:command, 'v'] don't work
+      find('body').native.send_keys [:shift, :insert]
+
+      expect(find('.js-main-target-form .js-vue-comment-form').value).to include(note_text)
+      expect(page).to have_css('.js-comment-button')
+      expect(page).not_to have_css('.js-comment-button[disabled]')
+    end
+  end
 end