msglist: Tapping a message in Starred or Mentions opens anchored msglist

Fixes zulip#1621.

Author: chrisbobbe

lib/widgets/message_list.dart

@@ -1,3 +1,5 @@
+import 'dart:async';
+
 import 'package:collection/collection.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter_color_models/flutter_color_models.dart';
@@ -989,11 +991,15 @@ class _MessageListState extends State<MessageList> with PerAccountStoreAwareStat
         final header = RecipientHeader(message: data.message, narrow: widget.narrow);
         return MessageItem(
           key: ValueKey(data.message.id),
+          narrow: widget.narrow,
           header: header,
           item: data);
       case MessageListOutboxMessageItem():
         final header = RecipientHeader(message: data.message, narrow: widget.narrow);
-        return MessageItem(header: header, item: data);
+        return MessageItem(
+          narrow: widget.narrow,
+          header: header,
+          item: data);
     }
   }
 }
@@ -1315,10 +1321,12 @@ class DateSeparator extends StatelessWidget {
 class MessageItem extends StatelessWidget {
   const MessageItem({
     super.key,
+    required this.narrow,
     required this.item,
     required this.header,
   });
 
+  final Narrow narrow;
   final MessageListMessageBaseItem item;
   final Widget header;
 
@@ -1331,7 +1339,9 @@ class MessageItem extends StatelessWidget {
       color: designVariables.bgMessageRegular,
       child: Column(children: [
         switch (item) {
-          MessageListMessageItem() => MessageWithPossibleSender(item: item),
+          MessageListMessageItem() => MessageWithPossibleSender(
+            narrow: narrow,
+            item: item),
           MessageListOutboxMessageItem() => OutboxMessageWithPossibleSender(item: item),
         },
         // TODO refine this padding; discussion:
@@ -1748,8 +1758,13 @@ class _SenderRow extends StatelessWidget {
 //   - https://github.com/zulip/zulip-mobile/issues/5511
 //   - https://www.figma.com/file/1JTNtYo9memgW7vV6d0ygq/Zulip-Mobile?node-id=538%3A20849&mode=dev
 class MessageWithPossibleSender extends StatelessWidget {
-  const MessageWithPossibleSender({super.key, required this.item});
+  const MessageWithPossibleSender({
+    super.key,
+    required this.narrow,
+    required this.item,
+  });
 
+  final Narrow narrow;
   final MessageListMessageItem item;
 
   @override
@@ -1798,8 +1813,24 @@ class MessageWithPossibleSender extends StatelessWidget {
       }
     }
 
+    final tapOpensConversation = switch (narrow) {
+      CombinedFeedNarrow()
+        || ChannelNarrow()
+        || TopicNarrow()
+        || DmNarrow() => false,
+      MentionsNarrow()
+        || StarredMessagesNarrow() => true,
+    };
+
     return GestureDetector(
       behavior: HitTestBehavior.translucent,
+      onTap: tapOpensConversation
+        ? () => unawaited(Navigator.push(context,
+            MessageListPage.buildRoute(context: context,
+              narrow: SendableNarrow.ofMessage(message, selfUserId: store.selfUserId),
+              // TODO(#1655) "this view does not mark messages as read on scroll"
+              initAnchorMessageId: message.id)))
+        : null,
       onLongPress: () => showMessageActionSheet(context: context, message: message),
       child: Padding(
         padding: const EdgeInsets.only(top: 4),

test/widgets/message_list_checks.dart

@@ -4,4 +4,5 @@ import 'package:zulip/widgets/message_list.dart';
 
 extension MessageListPageChecks on Subject<MessageListPage> {
   Subject<Narrow> get initNarrow => has((x) => x.initNarrow, 'initNarrow');
+  Subject<int?> get initAnchorMessageId => has((x) => x.initAnchorMessageId, 'initAnchorMessageId');
 }

test/widgets/message_list_test.dart

@@ -1653,6 +1653,82 @@ void main() {
 
       debugNetworkImageHttpClientProvider = null;
     });
+
+    group('Opens conversation on tap?', () {
+      // (copied from test/widgets/content_test.dart)
+      Future<void> tapText(WidgetTester tester, Finder textFinder) async {
+        final height = tester.getSize(textFinder).height;
+        final target = tester.getTopLeft(textFinder)
+          .translate(height/4, height/2); // aim for middle of first letter
+        await tester.tapAt(target);
+      }
+
+      final subscription = eg.subscription(eg.stream(streamId: eg.defaultStreamMessageStreamId));
+      final topic = 'some topic';
+
+      void doTest(Narrow narrow, {
+        required bool expected,
+        required Message Function() mkMessage,
+      }) {
+        testWidgets('${expected ? 'yes' : 'no'}, if in $narrow', (tester) async {
+          final message = mkMessage();
+
+          Route<dynamic>? lastPushedRoute;
+          final navObserver = TestNavigatorObserver()
+            ..onPushed = ((route, prevRoute) => lastPushedRoute = route);
+
+          await setupMessageListPage(
+            tester,
+            narrow: narrow,
+            messages: [message],
+            subscriptions: [subscription],
+            navObservers: [navObserver]
+          );
+          lastPushedRoute = null;
+
+          // Tapping interactive content still works.
+          await store.handleEvent(eg.updateMessageEditEvent(message,
+            renderedContent: '<p><a href="https://example/">link</a></p>'));
+          await tester.pump();
+          await tapText(tester, find.text('link'));
+          await tester.pump(Duration.zero);
+          check(lastPushedRoute).isNull();
+          final launchUrlCalls = testBinding.takeLaunchUrlCalls();
+          check(launchUrlCalls.single.url).equals(Uri.parse('https://example/'));
+
+          // Tapping non-interactive content opens the conversation (if expected).
+          await store.handleEvent(eg.updateMessageEditEvent(message,
+            renderedContent: '<p>plain content</p>'));
+          await tester.pump();
+          await tapText(tester, find.text('plain content'));
+          if (expected) {
+            final expectedNarrow = SendableNarrow.ofMessage(message, selfUserId: store.selfUserId);
+
+            check(lastPushedRoute).isNotNull().isA<MaterialAccountWidgetRoute>()
+              .page.isA<MessageListPage>()
+                ..initNarrow.equals(expectedNarrow)
+                ..initAnchorMessageId.equals(message.id);
+          } else {
+            check(lastPushedRoute).isNull();
+          }
+
+          // TODO test tapping whitespace in message
+        });
+      }
+
+      doTest(expected: false, CombinedFeedNarrow(),
+        mkMessage: () => eg.streamMessage());
+      doTest(expected: false, ChannelNarrow(subscription.streamId),
+        mkMessage: () => eg.streamMessage(stream: subscription));
+      doTest(expected: false, TopicNarrow(subscription.streamId, eg.t(topic)),
+        mkMessage: () => eg.streamMessage(stream: subscription));
+      doTest(expected: false, DmNarrow.withUsers([], selfUserId: eg.selfUser.userId),
+        mkMessage: () => eg.streamMessage(stream: subscription, topic: topic));
+      doTest(expected: true, StarredMessagesNarrow(),
+        mkMessage: () => eg.streamMessage(flags: [MessageFlag.starred]));
+      doTest(expected: true, MentionsNarrow(),
+        mkMessage: () => eg.streamMessage(flags: [MessageFlag.mentioned]));
+    });
   });
 
   group('OutboxMessageWithPossibleSender', () {