do not merge; api: Make displayName nullable

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

lib/api/model/model.dart

@@ -690,7 +690,7 @@ extension type const TopicName(String _value) {
   /// so that UI code can identify when it needs to represent the topic
   /// specially in the way prescribed for "general chat".
   // TODO(#1250) carry out that plan
-  String get displayName => _value;
+  String? get displayName => _value.isEmpty ? null : _value;
 
   /// The key to use for "same topic as" comparisons.
   String canonicalize() => apiName.toLowerCase();

lib/model/autocomplete.dart

@@ -942,15 +942,13 @@ class TopicAutocompleteQuery extends AutocompleteQuery {
   bool testTopic(PerAccountStore store, TopicName topic) {
     // 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());
     }
     // This checks for inequality because there is nothing to autocomplete to
     // when `raw` already matches the topic exactly.
     return topic.displayName != raw
-      // ignore: unnecessary_non_null_assertion // null topic names soon to be enabled
       && topic.displayName!.toLowerCase().contains(raw.toLowerCase());
   }
 

lib/widgets/autocomplete.dart

@@ -366,13 +366,11 @@ 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!);
     }
 

lib/widgets/compose_box.dart

@@ -182,7 +182,6 @@ class ComposeTopicController extends ComposeController<TopicValidationError> {
   }
 
   void setTopic(TopicName newTopic) {
-    // ignore: dead_null_aware_expression // null topic names soon to be enabled
     value = TextEditingValue(text: newTopic.displayName ?? '');
   }
 }

lib/widgets/inbox.dart

@@ -537,15 +537,13 @@ class _TopicItem extends StatelessWidget {
               child: Text(
                 style: TextStyle(
                   fontSize: 17,
-                  // ignore: unnecessary_null_comparison // null topic names soon to be enabled
                   fontStyle: topic.displayName == null ? FontStyle.italic : null,
                   height: (20 / 17),
                   // TODO(design) check if this is the right variable
                   color: designVariables.labelMenuButton,
                 ),
                 maxLines: 2,
                 overflow: TextOverflow.ellipsis,
-                // ignore: dead_null_aware_expression // null topic names soon to be enabled
                 topic.displayName ?? store.realmEmptyTopicDisplayName))),
             const SizedBox(width: 12),
             if (hasMention) const _IconMarker(icon: ZulipIcons.at_sign),

lib/widgets/message_list.dart

@@ -366,10 +366,8 @@ class MessageListAppBarTitle extends StatelessWidget {
     return Row(
       mainAxisSize: MainAxisSize.min,
       children: [
-        // ignore: dead_null_aware_expression // null topic names soon to be enabled
         Flexible(child: Text(topic.displayName ?? store.realmEmptyTopicDisplayName, style: TextStyle(
           fontSize: 13,
-          // ignore: unnecessary_null_comparison // null topic names soon to be enabled
           fontStyle: topic.displayName == null ? FontStyle.italic : null,
         ).merge(weightVariableTextStyle(context)))),
         if (icon != null)
@@ -1123,13 +1121,11 @@ class StreamMessageRecipientHeader extends StatelessWidget {
       child: Row(
         children: [
           Flexible(
-            // ignore: dead_null_aware_expression // null topic names soon to be enabled
             child: Text(topic.displayName ?? store.realmEmptyTopicDisplayName,
               // TODO: Give a way to see the whole topic (maybe a
               //   long-press interaction?)
               overflow: TextOverflow.ellipsis,
               style: recipientHeaderTextStyle(context).copyWith(
-                // ignore: unnecessary_null_comparison // null topic names soon to be enabled
                 fontStyle: topic.displayName == null ? FontStyle.italic : null,
               ))),
           const SizedBox(width: 4),

test/api/model/model_checks.dart

@@ -48,7 +48,7 @@ extension MessageChecks on Subject<Message> {
 
 extension TopicNameChecks on Subject<TopicName> {
   Subject<String> get apiName => has((x) => x.apiName, 'apiName');
-  Subject<String> get displayName => has((x) => x.displayName, 'displayName');
+  Subject<String?> get displayName => has((x) => x.displayName, 'displayName');
 }
 
 extension StreamMessageChecks on Subject<StreamMessage> {

test/widgets/action_sheet_test.dart

@@ -204,7 +204,7 @@ void main() {
 
       await tester.longPress(find.descendant(
         of: find.byType(RecipientHeader),
-        matching: find.text(effectiveMessage.topic.displayName)));
+        matching: find.text(effectiveMessage.topic.displayName!)));
       // sheet appears onscreen; default duration of bottom-sheet enter animation
       await tester.pump(const Duration(milliseconds: 250));
     }

test/widgets/autocomplete_test.dart

@@ -355,7 +355,7 @@ void main() {
       await tester.tap(find.text('Topic three'));
       await tester.pumpAndSettle();
       check(tester.widget<TextField>(topicInputFinder).controller!.text)
-        .equals(topic3.name.displayName);
+        .equals(topic3.name.displayName!);
       check(find.text('Topic one'  )).findsNothing();
       check(find.text('Topic two'  )).findsNothing();
       check(find.text('Topic three')).findsOne(); // shown in `_TopicInput` once
@@ -412,7 +412,7 @@ void main() {
       await tester.pumpAndSettle();
 
       check(find.text(eg.defaultRealmEmptyTopicDisplayName)).findsOne();
-    }, skip: true); // null topic names soon to be enabled
+    });
 
     testWidgets('match general chat in autocomplete', (tester) async {
       final topic = eg.getStreamTopicsEntry(name: '');
@@ -424,7 +424,7 @@ void main() {
       await tester.pumpAndSettle();
 
       check(find.text(eg.defaultRealmEmptyTopicDisplayName)).findsOne();
-    }, skip: true); // null topic names soon to be enabled
+    });
 
     testWidgets('autocomplete to general chat sets topic to empty string', (tester) async {
       final topic = eg.getStreamTopicsEntry(name: '');
@@ -439,6 +439,6 @@ void main() {
       await tester.tap(find.text(eg.defaultRealmEmptyTopicDisplayName));
       await tester.pump(Duration.zero);
       check(controller.value).text.equals('');
-    }, skip: true); // null topic names soon to be enabled
+    });
   });
 }

test/widgets/inbox_test.dart

@@ -315,7 +315,7 @@ void main() {
         unreadMessages: [eg.streamMessage(stream: channel, topic: '')]);
 
       check(find.text(eg.defaultRealmEmptyTopicDisplayName)).findsOne();
-    }, skip: true); // null topic names soon to be enabled
+    });
 
     group('topic visibility', () {
       final channel = eg.stream();

test/widgets/message_list_test.dart

@@ -943,7 +943,7 @@ void main() {
         await tester.pump();
         check(findInMessageList('stream name')).single;
         check(findInMessageList(eg.defaultRealmEmptyTopicDisplayName)).single;
-      }, skip: true); // null topic names soon to be enabled
+      });
 
       testWidgets('show general chat for empty topics without channel name', (tester) async {
         await setupMessageListPage(tester,
@@ -952,7 +952,7 @@ void main() {
         await tester.pump();
         check(findInMessageList('stream name')).isEmpty();
         check(findInMessageList(eg.defaultRealmEmptyTopicDisplayName)).single;
-      }, skip: true); // null topic names soon to be enabled
+      });
 
       testWidgets('show topic visibility icon when followed', (tester) async {
         await setupMessageListPage(tester,