autocomplete [nfc]: Handle autocompleting to empty topic

While this appears to be a user facing change, it's not visible yet, not
until TopicName.displayName becomes nullable.  This is a part of a
series of changes to handle empty topics.

Signed-off-by: Zixuan James Li <[email protected]>

Author: PIG208

lib/model/autocomplete.dart

@@ -921,7 +921,7 @@ class TopicAutocompleteView extends AutocompleteView<TopicAutocompleteQuery, Top
   }
 
   TopicAutocompleteResult? _testTopic(TopicAutocompleteQuery query, TopicName topic) {
-    if (query.testTopic(topic)) {
+    if (query.testTopic(topic, store)) {
       return TopicAutocompleteResult(topic: topic);
     }
     return null;
@@ -939,10 +939,17 @@ class TopicAutocompleteView extends AutocompleteView<TopicAutocompleteQuery, Top
 class TopicAutocompleteQuery extends AutocompleteQuery {
   TopicAutocompleteQuery(super.raw);
 
-  bool testTopic(TopicName topic) {
+  bool testTopic(TopicName topic, PerAccountStore store) {
     // TODO(#881): Sort by match relevance, like web does.
+
+    // ignore: unnecessary_null_comparison // null topic names soon to be enabled
+    if (topic.displayName == null) {
+      return store.realmEmptyTopicDisplayName.toLowerCase()
+        .contains(raw.toLowerCase());
+    }
     return topic.displayName != raw
-      && topic.displayName.toLowerCase().contains(raw.toLowerCase());
+      // ignore: unnecessary_non_null_assertion // null topic names soon to be enabled
+      && topic.displayName!.toLowerCase().contains(raw.toLowerCase());
   }
 
   @override

lib/widgets/autocomplete.dart

@@ -415,12 +415,23 @@ class TopicAutocomplete extends AutocompleteField<TopicAutocompleteQuery, TopicA
 
   @override
   Widget buildItem(BuildContext context, int index, TopicAutocompleteResult option) {
+    final Widget child;
+    // ignore: unnecessary_null_comparison // null topic names soon to be enabled
+    if (option.topic.displayName == null) {
+      final store = PerAccountStoreWidget.of(context);
+      child = Text(store.realmEmptyTopicDisplayName,
+        style: const TextStyle(fontStyle: FontStyle.italic));
+    } else {
+      // ignore: unnecessary_non_null_assertion // null topic names soon to be enabled
+      child = Text(option.topic.displayName!);
+    }
+
     return InkWell(
       onTap: () {
         _onTapOption(context, option);
       },
       child: Padding(
         padding: const EdgeInsets.symmetric(horizontal: 16.0, vertical: 8.0),
-        child: Text(option.topic.displayName)));
+        child: child));
   }
 }

lib/widgets/compose_box.dart

@@ -182,7 +182,8 @@ class ComposeTopicController extends ComposeController<TopicValidationError> {
   }
 
   void setTopic(TopicName newTopic) {
-    value = TextEditingValue(text: newTopic.displayName);
+    // ignore: dead_null_aware_expression // null topic names soon to be enabled
+    value = TextEditingValue(text: newTopic.displayName ?? '');
   }
 }
 

test/model/autocomplete_test.dart

@@ -1027,8 +1027,9 @@ void main() {
   });
 
   group('TopicAutocompleteQuery.testTopic', () {
+    final store = eg.store();
     void doCheck(String rawQuery, String topic, bool expected) {
-      final result = TopicAutocompleteQuery(rawQuery).testTopic(eg.t(topic));
+      final result = TopicAutocompleteQuery(rawQuery).testTopic(eg.t(topic), store);
       expected ? check(result).isTrue() : check(result).isFalse();
     }
 

test/widgets/autocomplete_test.dart

@@ -99,9 +99,11 @@ Future<Finder> setupToComposeInput(WidgetTester tester, {
 /// Returns a [Finder] for the topic input's [TextField].
 Future<Finder> setupToTopicInput(WidgetTester tester, {
   required List<GetStreamTopicsEntry> topics,
+  String? realmEmptyTopicDisplayName,
 }) async {
   addTearDown(testBinding.reset);
-  await testBinding.globalStore.add(eg.selfAccount, eg.initialSnapshot());
+  await testBinding.globalStore.add(eg.selfAccount, eg.initialSnapshot(
+    realmEmptyTopicDisplayName: realmEmptyTopicDisplayName));
   final store = await testBinding.globalStore.perAccount(eg.selfAccount.id);
   await store.addUser(eg.selfUser);
   final connection = store.connection as FakeApiConnection;
@@ -459,5 +461,47 @@ void main() {
 
       await tester.pump(Duration.zero);
     });
+
+    testWidgets('display realmEmptyTopicDisplayName for empty topic', (tester) async {
+      final topic = eg.getStreamTopicsEntry(name: '');
+      final topicInputFinder = await setupToTopicInput(tester, topics: [topic],
+        realmEmptyTopicDisplayName: 'some display name');
+
+      // TODO(#226): Remove this extra edit when this bug is fixed.
+      await tester.enterText(topicInputFinder, ' ');
+      await tester.enterText(topicInputFinder, '');
+      await tester.pumpAndSettle();
+
+      check(find.text('some display name')).findsOne();
+    }, skip: true); // null topic names soon to be enabled
+
+    testWidgets('match realmEmptyTopicDisplayName in autocomplete', (tester) async {
+      final topic = eg.getStreamTopicsEntry(name: '');
+      final topicInputFinder = await setupToTopicInput(tester, topics: [topic],
+        realmEmptyTopicDisplayName: 'general chat');
+
+      // TODO(#226): Remove this extra edit when this bug is fixed.
+      await tester.enterText(topicInputFinder, 'general ch');
+      await tester.enterText(topicInputFinder, 'general cha');
+      await tester.pumpAndSettle();
+
+      check(find.text('general chat')).findsOne();
+    }, skip: true); // null topic names soon to be enabled
+
+    testWidgets('autocomplete to realmEmptyTopicDisplayName sets topic to empty string', (tester) async {
+      final topic = eg.getStreamTopicsEntry(name: '');
+      final topicInputFinder = await setupToTopicInput(tester, topics: [topic],
+        realmEmptyTopicDisplayName: 'general chat');
+      final controller = tester.widget<TextField>(topicInputFinder).controller!;
+
+      // TODO(#226): Remove this extra edit when this bug is fixed.
+      await tester.enterText(topicInputFinder, 'general ch');
+      await tester.enterText(topicInputFinder, 'general cha');
+      await tester.pumpAndSettle();
+
+      await tester.tap(find.text('general chat'));
+      await tester.pump(Duration.zero);
+      check(controller.value).text.equals('');
+    }, skip: true); // null topic names soon to be enabled
   });
 }