Move spec and add one for merge button not disabled.

spec/features/merge_requests/widget_spec.rb

@@ -206,4 +206,33 @@ describe 'Merge request', :feature, :js do
       end
     end
   end
+
+  context 'user can merge into source project but cannot push to fork', js: true do
+    let(:fork_project) { create(:project, :public) }
+
+    let!(:merge_request_from_fork) do
+      create(:forked_project_link, forked_to_project: fork_project,
+                                   forked_from_project: project)
+
+      create(:merge_request_with_diffs, source_project: fork_project,
+                                        target_project: project)
+    end
+
+    let(:user2) { create(:user) }
+
+    before do
+      project.team << [user2, :master]
+      logout
+      login_as user2
+      visit namespace_project_merge_request_path(project.namespace, project, merge_request_from_fork)
+    end
+
+    it 'user can merge into the source project' do
+      expect(page).to have_button('Merge', disabled: false)
+    end
+
+    it 'user cannot remove source branch' do
+      expect(page).to have_field('remove-source-branch-input', disabled: true)
+    end
+  end
 end