Use ZulipIcons.check icon for resolved topics in the UI (except topic autocomplete)

lib/widgets/text.dart

@@ -831,12 +831,49 @@ class InlineIcon extends StatelessWidget {
   }
 }
 
+/// An [InlineSpan] with a [ZulipIcons.check] icon (if resolved) and topic name.
+///
+/// Pass this to [Text.rich], which can be styled arbitrarily.
+/// Pass the [fontSize] and [color] of surrounding text
+/// so that the icons are sized and colored appropriately.
+///
+/// For a span with a channel name/icon and optional topic,
+/// see [channelTopicLabelSpan].
+InlineSpan topicLabelSpan({
+  required BuildContext context,
+  required TopicName topic,
+  required double fontSize,
+  required Color color,
+}) {
+  final store = PerAccountStoreWidget.of(context);
+  final baselineType = localizedTextBaseline(context);
+
+  return TextSpan(children: [
+    if (topic.isResolved)
+      InlineIcon.asWidgetSpan(
+        icon: ZulipIcons.check,
+        fontSize: fontSize,
+        baselineType: baselineType,
+        color: color,
+        padAfter: true),
+    if (topic.unresolve().displayName != null)
+      TextSpan(text: topic.unresolve().displayName)
+    else
+      TextSpan(
+        style: TextStyle(fontStyle: FontStyle.italic),
+        text: store.realmEmptyTopicDisplayName),
+  ]);
+}
+
 /// An [InlineSpan] with a channel privacy icon, channel name,
 /// and optionally a chevron-right icon plus topic.
 ///
 /// Pass this to [Text.rich], which can be styled arbitrarily.
 /// Pass the [fontSize] and [color] of surrounding text
 /// so that the icons are sized and colored appropriately.
+///
+/// For a span with just the topic (including checkmark icon as applicable)
+/// see [topicLabelSpan].
 InlineSpan channelTopicLabelSpan({
   required BuildContext context,
   required int channelId,
@@ -874,12 +911,11 @@ InlineSpan channelTopicLabelSpan({
         color: color,
         padBefore: true,
         padAfter: true),
-      if (topic.displayName != null)
-        TextSpan(text: topic.displayName)
-      else
-        TextSpan(
-          style: TextStyle(fontStyle: FontStyle.italic),
-          text: store.realmEmptyTopicDisplayName),
+      topicLabelSpan(
+        context: context,
+        topic: topic,
+        fontSize: fontSize,
+        color: color),
     ],
   ]);
 }

test/widgets/text_test.dart

@@ -3,8 +3,11 @@ import 'package:collection/collection.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter_checks/flutter_checks.dart';
 import 'package:flutter_test/flutter_test.dart';
+import 'package:zulip/api/model/model.dart';
+import 'package:zulip/widgets/icons.dart';
 import 'package:zulip/widgets/text.dart';
 
+import '../example_data.dart' as eg;
 import '../flutter_checks.dart';
 import '../model/binding.dart';
 import 'test_app.dart';
@@ -420,6 +423,101 @@ void main() {
     testLocalizedTextBaseline(const Locale('und'), TextBaseline.alphabetic);
   });
 
+  group('topicLabelSpan', () {
+    Future<void> prepareWidget(WidgetTester tester, {
+      required TopicName topic,
+      String? realmEmptyTopicDisplayName,
+    }) async {
+      addTearDown(testBinding.reset);
+      await testBinding.globalStore.add(eg.selfAccount, eg.initialSnapshot(
+        realmEmptyTopicDisplayName: realmEmptyTopicDisplayName));
+
+      await tester.pumpWidget(TestZulipApp(accountId: eg.selfAccount.id,
+        child: Builder(builder: (context) => Text.rich(
+          topicLabelSpan(
+            context: context,
+            topic: topic,
+            fontSize: 17,
+            color: Colors.black)))));
+      await tester.pump(); // global store
+      await tester.pump(); // per-account store
+    }
+
+    Finder findCheckIcon() => find.byWidgetPredicate(
+      (w) => w is InlineIcon && w.icon == ZulipIcons.check);
+
+    testWidgets('resolved topic shows checkmark and strips prefix', (tester) async {
+      await prepareWidget(tester, topic: eg.t('✔ some topic'));
+      check(findCheckIcon()).findsOne();
+      check(find.textContaining('some topic', findRichText: true)).findsOne();
+      check(find.textContaining('✔', findRichText: true)).findsNothing();
+    });
+
+    testWidgets('unresolved topic shows no checkmark', (tester) async {
+      await prepareWidget(tester, topic: eg.t('some topic'));
+      check(findCheckIcon()).findsNothing();
+      check(find.textContaining('some topic', findRichText: true)).findsOne();
+    });
+
+    testWidgets('empty topic shows italic placeholder', (tester) async {
+      await prepareWidget(tester, topic: eg.t(''),
+        realmEmptyTopicDisplayName: 'general chat');
+      check(find.textContaining('general chat', findRichText: true)).findsOne();
+
+      FontStyle? italicFontStyle;
+      final richText = tester.widget<RichText>(
+        find.textContaining('general chat', findRichText: true));
+      richText.text.visitChildren((span) {
+        if (span is TextSpan && span.text == 'general chat') {
+          italicFontStyle = span.style?.fontStyle;
+          return false;
+        }
+        return true;
+      });
+      check(italicFontStyle).equals(FontStyle.italic);
+    });
+  });
+
+  group('channelTopicLabelSpan', () {
+    final channel = eg.stream();
+
+    Future<void> prepareWidget(WidgetTester tester, {
+      required TopicName topic,
+    }) async {
+      addTearDown(testBinding.reset);
+      await testBinding.globalStore.add(eg.selfAccount, eg.initialSnapshot(
+        streams: [channel],
+        subscriptions: [eg.subscription(channel)]));
+
+      await tester.pumpWidget(TestZulipApp(accountId: eg.selfAccount.id,
+        child: Builder(builder: (context) => Text.rich(
+          channelTopicLabelSpan(
+            context: context,
+            channelId: channel.streamId,
+            topic: topic,
+            fontSize: 17,
+            color: Colors.black)))));
+      await tester.pump(); // global store
+      await tester.pump(); // per-account store
+    }
+
+    Finder findCheckIcon() => find.byWidgetPredicate(
+      (w) => w is InlineIcon && w.icon == ZulipIcons.check);
+
+    testWidgets('resolved topic shows checkmark and strips prefix', (tester) async {
+      await prepareWidget(tester, topic: eg.t('✔ some topic'));
+      check(findCheckIcon()).findsOne();
+      check(find.textContaining('some topic', findRichText: true)).findsOne();
+      check(find.textContaining('✔', findRichText: true)).findsNothing();
+    });
+
+    testWidgets('unresolved topic shows no checkmark', (tester) async {
+      await prepareWidget(tester, topic: eg.t('some topic'));
+      check(findCheckIcon()).findsNothing();
+      check(find.textContaining('some topic', findRichText: true)).findsOne();
+    });
+  });
+
   group('TextWithLink', () {
     testWidgets('responds correctly to taps', (tester) async {
       int calls = 0;