Fix MR sidebar to correctly warning if assignee can't merge

app/views/shared/issuable/_sidebar_assignees.html.haml

@@ -25,7 +25,7 @@
   .value.hide-collapsed
     - if issuable_sidebar[:assignee]
       = link_to_member(@project, assignee, size: 32, extra_class: 'bold') do
-        - if issuable_sidebar[:assignee][:can_merge]
+        - unless issuable_sidebar[:assignee][:can_merge]
           %span.float-right.cannot-be-merged{ data: { toggle: 'tooltip', placement: 'left' }, title: _('Not allowed to merge') }
             = icon('exclamation-triangle', 'aria-hidden': 'true')
         %span.username

spec/views/projects/merge_requests/show.html.haml_spec.rb

@@ -32,11 +32,7 @@ describe 'projects/merge_requests/show.html.haml' do
     assign(:noteable, closed_merge_request)
     assign(:notes, [])
     assign(:pipelines, Ci::Pipeline.none)
-    assign(
-      :issuable_sidebar,
-      MergeRequestSerializer.new(current_user: user, project: project)
-        .represent(closed_merge_request, serializer: 'sidebar')
-    )
+    assign(:issuable_sidebar, serialize_issuable_sidebar(user, project, closed_merge_request))
 
     preload_view_requirements
 
@@ -45,6 +41,33 @@ describe 'projects/merge_requests/show.html.haml' do
                                     current_application_settings: Gitlab::CurrentSettings.current_application_settings)
   end
 
+  describe 'merge request assignee sidebar' do
+    context 'when assignee is allowed to merge' do
+      it 'does not show a warning icon' do
+        closed_merge_request.update(assignee_id: user.id)
+        project.add_maintainer(user)
+        assign(:issuable_sidebar, serialize_issuable_sidebar(user, project, closed_merge_request))
+
+        render
+
+        expect(rendered).not_to have_css('.cannot-be-merged')
+      end
+    end
+
+    context 'when assignee is not allowed to merge' do
+      it 'shows a warning icon' do
+        reporter = create(:user)
+        project.add_reporter(reporter)
+        closed_merge_request.update(assignee_id: reporter.id)
+        assign(:issuable_sidebar, serialize_issuable_sidebar(user, project, closed_merge_request))
+
+        render
+
+        expect(rendered).to have_css('.cannot-be-merged')
+      end
+    end
+  end
+
   context 'when the merge request is closed' do
     it 'shows the "Reopen" button' do
       render
@@ -80,4 +103,10 @@ describe 'projects/merge_requests/show.html.haml' do
       expect(rendered).to have_css('a', visible: false, text: 'Close')
     end
   end
+
+  def serialize_issuable_sidebar(user, project, merge_request)
+    MergeRequestSerializer
+      .new(current_user: user, project: project)
+      .represent(closed_merge_request, serializer: 'sidebar')
+  end
 end