Add snippets autocomplete to tribute

We are migrating from jQuery-based at.js to tribute behind
the feature flag :tribute_autocomplete. This commit
adds snippets autocomplete to tribute.

app/assets/javascripts/vue_shared/components/gl_mentions.vue

@@ -11,6 +11,7 @@ const AutoComplete = {
   Members: 'members',
   MergeRequests: 'mergeRequests',
   Milestones: 'milestones',
+  Snippets: 'snippets',
 };
 
 const groupType = 'Group'; // eslint-disable-line @gitlab/require-i18n-strings
@@ -129,6 +130,14 @@ const autoCompleteMap = {
       return escape(original.title);
     },
   },
+  [AutoComplete.Snippets]: {
+    filterValues() {
+      return this[AutoComplete.Snippets];
+    },
+    menuItemTemplate({ original }) {
+      return `<small>${original.id}</small> ${escape(original.title)}`;
+    },
+  },
 };
 
 export default {
@@ -184,6 +193,13 @@ export default {
           selectTemplate: ({ original }) => `%"${escape(original.title)}"`,
           values: this.getValues(AutoComplete.Milestones),
         },
+        {
+          trigger: '$',
+          fillAttr: 'id',
+          lookup: value => value.id + value.title,
+          menuItemTemplate: autoCompleteMap[AutoComplete.Snippets].menuItemTemplate,
+          values: this.getValues(AutoComplete.Snippets),
+        },
       ],
     });
 

app/assets/javascripts/vue_shared/components/markdown/field.vue

@@ -177,7 +177,7 @@ export default {
         epics: this.enableAutocomplete,
         milestones: this.enableAutocomplete && !this.glFeatures.tributeAutocomplete,
         labels: this.enableAutocomplete && !this.glFeatures.tributeAutocomplete,
-        snippets: this.enableAutocomplete,
+        snippets: this.enableAutocomplete && !this.glFeatures.tributeAutocomplete,
       },
       true,
     );

spec/features/issues/gfm_autocomplete_spec.rb

@@ -814,6 +814,13 @@ RSpec.describe 'GFM autocomplete', :js do
       end
     end
 
+    context 'issues' do
+      let(:object) { issue }
+      let(:expected_body) { object.to_reference }
+
+      it_behaves_like 'autocomplete suggestions'
+    end
+
     context 'merge requests' do
       let(:object) { create(:merge_request, source_project: project) }
       let(:expected_body) { object.to_reference }
@@ -821,6 +828,27 @@ RSpec.describe 'GFM autocomplete', :js do
       it_behaves_like 'autocomplete suggestions'
     end
 
+    context 'project snippets' do
+      let!(:object) { create(:project_snippet, project: project, title: 'code snippet') }
+      let(:expected_body) { object.to_reference }
+
+      it_behaves_like 'autocomplete suggestions'
+    end
+
+    context 'label' do
+      let!(:object) { label }
+      let(:expected_body) { object.title }
+
+      it_behaves_like 'autocomplete suggestions'
+    end
+
+    context 'milestone' do
+      let!(:object) { create(:milestone, project: project) }
+      let(:expected_body) { object.to_reference }
+
+      it_behaves_like 'autocomplete suggestions'
+    end
+
     context 'when other notes are destroyed' do
       let!(:discussion) { create(:discussion_note_on_issue, noteable: issue, project: issue.project) }