msglist: In unsubscribed channel, refresh on message-send success

This fixes half of the "first buggy behavior" described in zulip#1798,
specifically the send-message case. We'll fix it for the
edit-message case too, coming up.

Fixes-partly: zulip#1798

Author: chrisbobbe

lib/widgets/compose_box.dart

@@ -1324,13 +1324,14 @@ class _SendButtonState extends State<_SendButton> {
       return;
     }
 
-    final store = PerAccountStoreWidget.of(context);
+    PerAccountStore store = PerAccountStoreWidget.of(context);
     final content = controller.content.textNormalized;
 
     controller.content.clear();
 
     try {
       await store.sendMessage(destination: widget.getDestination(), content: content);
+      if (!mounted) return;
     } on ApiRequestException catch (e) {
       if (!mounted) return;
       final zulipLocalizations = ZulipLocalizations.of(context);
@@ -1343,6 +1344,20 @@ class _SendButtonState extends State<_SendButton> {
         message: message);
       return;
     }
+
+    store = PerAccountStoreWidget.of(context);
+    final destination = widget.getDestination();
+    if (
+      destination is StreamDestination
+      && store.subscriptions[destination.streamId] == null
+    ) {
+      // We don't get new-message events for unsubscribed channels,
+      // but we can refresh the view when a send-message request succeeds,
+      // so the user will at least see their own messages without having to
+      // exit and re-enter. See the "first buggy behavior" in
+      //   https://github.com/zulip/zulip-flutter/issues/1798 .
+      MessageListPage.ancestorOf(context).refresh(AnchorCode.newest);
+    }
   }
 
   @override

test/widgets/compose_box_test.dart

@@ -14,6 +14,7 @@ import 'package:flutter/material.dart';
 import 'package:image_picker/image_picker.dart';
 import 'package:zulip/api/model/events.dart';
 import 'package:zulip/api/model/model.dart';
+import 'package:zulip/api/model/narrow.dart';
 import 'package:zulip/api/route/channels.dart';
 import 'package:zulip/api/route/messages.dart';
 import 'package:zulip/model/localizations.dart';
@@ -972,6 +973,59 @@ void main() {
           'You do not have permission to initiate direct message conversations.'),
       )));
     });
+
+    testWidgets('if channel is unsubscribed, refresh on message-send success', (tester) async {
+      // Regression test for the "first buggy behavior"
+      // in https://github.com/zulip/zulip-flutter/issues/1798 .
+      TypingNotifier.debugEnable = false;
+      addTearDown(TypingNotifier.debugReset);
+      assert(MessageStoreImpl.debugOutboxEnable);
+
+      final channel = eg.stream();
+      final narrow = eg.topicNarrow(channel.streamId, 'some topic');
+      final messages = [eg.streamMessage(stream: channel, topic: 'some topic')];
+      final zulipLocalizations = GlobalLocalizations.zulipLocalizations;
+      await prepareComposeBox(tester,
+        narrow: narrow,
+        streams: [channel],
+        messages: messages);
+      assert(store.subscriptions[channel.streamId] == null);
+
+      await enterContent(tester, 'hello world');
+
+      connection.prepare(
+        json: SendMessageResult(id: 456).toJson(), delay: Duration(seconds: 1));
+      await tester.tap(find.byTooltip(zulipLocalizations.composeBoxSendTooltip));
+      await tester.pump(Duration(milliseconds: 500));
+      check(connection.takeRequests()).single.isA<http.Request>()
+        ..method.equals('POST')
+        ..url.path.equals('/api/v1/messages');
+
+      final newMessage = eg.streamMessage(
+        stream: channel, topic: 'some topic',
+        content: '<p>hello world</p>');
+      connection.prepare(json: eg.newestGetMessagesResult(
+        foundOldest: true, messages: [...messages, newMessage]).toJson());
+      await tester.pump(Duration(milliseconds: 500));
+      check(connection.lastRequest).isA<http.Request>()
+        ..method.equals('GET')
+        ..url.path.equals('/api/v1/messages')
+        ..url.queryParameters.deepEquals({
+          'narrow': jsonEncode(resolveApiNarrowForServer(
+            narrow.apiEncode(), connection.zulipFeatureLevel!)),
+          'anchor': 'newest',
+          'num_before': '100',
+          'num_after': '100',
+          'allow_empty_topic_name': 'true',
+        });
+      check(find.descendant(
+        of: find.byType(MessageWithPossibleSender),
+        matching: find.text('hello world'))
+      ).findsOne();
+      // TODO(#1798) There's actually a lingering OutboxMessageWithPossibleSender,
+      //   too (the "third buggy behavior" in #1798). We'll fix that soon,
+      //   and it'll be convenient to test that here too.
+    });
   });
 
   group('sending to empty topic', () {