msglist: In single-conversation view, make recipient headers not tappable.

Fixes: zulip#1171

Author: lakshya1goel

lib/widgets/message_list.dart

@@ -899,8 +899,9 @@ class RecipientHeader extends StatelessWidget {
     final message = this.message;
     return switch (message) {
       StreamMessage() => StreamMessageRecipientHeader(message: message,
-        showStream: _containsDifferentChannels(narrow)),
-      DmMessage() => DmRecipientHeader(message: message),
+        showStream: _containsDifferentChannels(narrow),
+        inTopicNarrow: narrow is TopicNarrow),
+      DmMessage() => DmRecipientHeader(message: message, inDmNarrow: narrow is DmNarrow),
     };
   }
 }
@@ -1015,10 +1016,12 @@ class StreamMessageRecipientHeader extends StatelessWidget {
     super.key,
     required this.message,
     required this.showStream,
+    required this.inTopicNarrow,
   });
 
   final StreamMessage message;
   final bool showStream;
+  final bool inTopicNarrow;
 
   @override
   Widget build(BuildContext context) {
@@ -1104,10 +1107,15 @@ class StreamMessageRecipientHeader extends StatelessWidget {
               store.topicVisibilityPolicy(message.streamId, topic))),
         ]));
 
+    // When already in a topic narrow, disable tap interaction that would just
+    // push a MessageListPage for the same topic narrow.
+    // TODO(#1039) simplify by removing topic-narrow condition if we remove
+    //   recipient headers in topic narrows
     return GestureDetector(
-      onTap: () => Navigator.push(context,
-        MessageListPage.buildRoute(context: context,
-          narrow: TopicNarrow.ofMessage(message))),
+      onTap: !inTopicNarrow
+        ? () => Navigator.push(context, MessageListPage.buildRoute(context: context,
+          narrow: TopicNarrow.ofMessage(message)))
+        : null,
       onLongPress: () => showTopicActionSheet(context,
         channelId: message.streamId, topic: topic),
       child: ColoredBox(
@@ -1126,9 +1134,10 @@ class StreamMessageRecipientHeader extends StatelessWidget {
 }
 
 class DmRecipientHeader extends StatelessWidget {
-  const DmRecipientHeader({super.key, required this.message});
+  const DmRecipientHeader({super.key, required this.message, required this.inDmNarrow});
 
   final DmMessage message;
+  final bool inDmNarrow;
 
   @override
   Widget build(BuildContext context) {
@@ -1148,10 +1157,15 @@ class DmRecipientHeader extends StatelessWidget {
 
     final messageListTheme = MessageListTheme.of(context);
 
+    // When already in a DM narrow, disable tap interaction that would just
+    // push a MessageListPage for the same DM narrow.
+    // TODO(#1244) simplify by removing DM-narrow condition if we remove
+    //   recipient headers in DM narrows
     return GestureDetector(
-      onTap: () => Navigator.push(context,
-        MessageListPage.buildRoute(context: context,
-          narrow: DmNarrow.ofMessage(message, selfUserId: store.selfUserId))),
+      onTap: !inDmNarrow
+        ? () => Navigator.push(context, MessageListPage.buildRoute(context: context,
+          narrow: DmNarrow.ofMessage(message, selfUserId: store.selfUserId)))
+        : null,
       child: ColoredBox(
         color: messageListTheme.dmRecipientHeaderBg,
         child: Padding(

test/widgets/message_list_test.dart

@@ -922,6 +922,72 @@ void main() {
         await tester.pump();
         tester.widget(find.text('new stream name'));
       });
+
+      testWidgets('navigates to TopicNarrow on tapping topic in CombinedFeedNarrow', (tester) async {
+        final pushedRoutes = <Route<void>>[];
+        final navObserver = TestNavigatorObserver()
+          ..onPushed = (route, prevRoute) => pushedRoutes.add(route);
+
+        final channel = eg.stream();
+        final message = eg.streamMessage(stream: channel, topic: 'topic name');
+
+        await setupMessageListPage(
+          tester,
+          narrow: const CombinedFeedNarrow(),
+          messages: [message],
+          subscriptions: [eg.subscription(channel)],
+          navObservers: [navObserver],
+        );
+
+        assert(pushedRoutes.length == 1);
+        pushedRoutes.clear();
+
+        connection.prepare(json: eg.newestGetMessagesResult(
+          messages: [message],
+          foundOldest: true,
+        ).toJson());
+
+        final topicFinder = find.descendant(
+          of: find.byType(StreamMessageRecipientHeader),
+          matching: find.text('topic name'),
+        );
+        await tester.tap(topicFinder);
+        await tester.pumpAndSettle();
+
+        check(pushedRoutes).single
+          .isA<WidgetRoute>()
+          .page.isA<MessageListPage>()
+          .initNarrow.equals(TopicNarrow(channel.streamId, 'topic name'));
+      });
+
+      testWidgets('does not navigate on tapping topic in TopicNarrow', (tester) async {
+        final pushedRoutes = <Route<void>>[];
+        final navObserver = TestNavigatorObserver()
+          ..onPushed = (route, prevRoute) => pushedRoutes.add(route);
+
+        final channel = eg.stream();
+        final message = eg.streamMessage(stream: channel, topic: 'topic name');
+
+        await setupMessageListPage(
+          tester,
+          narrow: TopicNarrow(channel.streamId, 'topic name'),
+          navObservers: [navObserver],
+          streams: [channel],
+          messages: [message],
+        );
+
+        assert(pushedRoutes.length == 1);
+        pushedRoutes.clear();
+
+        final topicFinder = find.descendant(
+          of: find.byType(StreamMessageRecipientHeader),
+          matching: find.text('topic name'),
+        );
+        await tester.tap(topicFinder);
+        await tester.pumpAndSettle();
+
+        check(pushedRoutes).isEmpty();
+      });
     });
 
     group('DmRecipientHeader', () {
@@ -987,6 +1053,62 @@ void main() {
       tester.widget(find.textContaining(RegExp("Dec 1[89], 2022")));
       tester.widget(find.textContaining(RegExp("Aug 2[23], 2022")));
     });
+
+    testWidgets('navigates to DmNarrow on tapping recipient header in CombinedFeedNarrow', (tester) async {
+      final pushedRoutes = <Route<void>>[];
+      final navObserver = TestNavigatorObserver()
+          ..onPushed = (route, prevRoute) => pushedRoutes.add(route);
+
+      final dmMessage = eg.dmMessage(from: eg.selfUser, to: [eg.otherUser]);
+
+      await setupMessageListPage(
+        tester,
+        narrow: const CombinedFeedNarrow(),
+        messages: [dmMessage],
+        navObservers: [navObserver],
+      );
+
+      assert(pushedRoutes.length == 1);
+      pushedRoutes.clear();
+
+      connection.prepare(json: eg.newestGetMessagesResult(
+        messages: [dmMessage],
+        foundOldest: true,
+      ).toJson());
+
+      final recipientHeaderFinder = find.byType(DmRecipientHeader);
+      await tester.tap(recipientHeaderFinder);
+      await tester.pumpAndSettle();
+
+      check(pushedRoutes).single
+        .isA<WidgetRoute>()
+        .page.isA<MessageListPage>()
+        .initNarrow.equals(DmNarrow.withUser(eg.otherUser.userId, selfUserId: eg.selfUser.userId));
+    });
+
+    testWidgets('does not navigate on tapping recipient header in DmNarrow', (tester) async {
+      final pushedRoutes = <Route<void>>[];
+      final navObserver = TestNavigatorObserver()
+        ..onPushed = (route, prevRoute) => pushedRoutes.add(route);
+
+      final dmMessage = eg.dmMessage(from: eg.selfUser, to: [eg.otherUser]);
+
+      await setupMessageListPage(
+        tester,
+        narrow: DmNarrow.withUser(eg.otherUser.userId, selfUserId: eg.selfUser.userId),
+        navObservers: [navObserver],
+        messages: [dmMessage],
+      );
+
+      assert(pushedRoutes.length == 1);
+      pushedRoutes.clear();
+
+      final recipientHeaderFinder = find.byType(DmRecipientHeader);
+      await tester.tap(recipientHeaderFinder);
+      await tester.pumpAndSettle();
+
+      check(pushedRoutes).isEmpty();
+    });
   });
 
   group('formatHeaderDate', () {