home: Add search button and related tests.

Adds a search icon and tooltip to the icon in the home page app bar
that appears on the inbox tab. Uses the same localized 'Search' text
for consistency with the message list search button.

Also refactors the app bar actions logic by extracting it into a
_currentTabAppBarActions getter.

Updates the existing bottom nav navigation test inside home_test to verify search button presence
across different tabs: present on inbox, absent on channels and
direct messages tabs.

Also updates the existing InboxPage tests to verify the search button navigates to search page when tapped

Author: Komal Singh

lib/widgets/home.dart

@@ -84,6 +84,23 @@ class _HomePageState extends State<HomePage> {
     }
   }
 
+  List<Widget>? get _currentTabAppBarActions {
+    switch(_tab.value) {
+      case _HomePageTab.inbox:
+        return [
+          IconButton(
+            icon: const Icon(ZulipIcons.search),
+            tooltip: ZulipLocalizations.of(context).searchMessagesPageTitle,
+            onPressed: () => Navigator.of(context).push(MessageListPage.buildRoute(
+              context: context, narrow: KeywordSearchNarrow(''))),
+          ),
+        ];
+      case _HomePageTab.channels:
+      case _HomePageTab.directMessages:
+        return null;
+    }
+  }
+
   @override
   Widget build(BuildContext context) {
     const pageBodies = [
@@ -120,7 +137,9 @@ class _HomePageState extends State<HomePage> {
     final designVariables = DesignVariables.of(context);
     return Scaffold(
       appBar: ZulipAppBar(titleSpacing: 16,
-        title: Text(_currentTabTitle)),
+        title: Text(_currentTabTitle),
+        actions: _currentTabAppBarActions
+      ),
       body: Stack(
         children: [
           for (final (tab, body) in pageBodies)

test/widgets/home_test.dart

@@ -111,24 +111,40 @@ void main () {
       check(find.byIcon(ZulipIcons.arrow_right)).findsExactly(2);
     });
 
-    testWidgets('update app bar title when switching between views', (tester) async {
+    testWidgets('update app bar title and actions when switching between views', (tester) async {
       await prepare(tester);
 
+      // Helper to check if search button is present
+      bool hasSearchButton() {
+        final appBar = tester.widget<ZulipAppBar>(find.byType(ZulipAppBar));
+        final actions = appBar.actions ?? [];
+        return actions.any((widget) =>
+          widget is IconButton &&
+          widget.icon is Icon &&
+          (widget.icon as Icon).icon == ZulipIcons.search);
+      }
+
+      // Inbox tab: should have title "Inbox" and search button
       check(find.descendant(
         of: find.byType(ZulipAppBar),
         matching: find.text('Inbox'))).findsOne();
+      check(hasSearchButton()).isTrue();
 
+      // Channels tab: should have title "Channels" and no search button
       await tester.tap(find.byIcon(ZulipIcons.hash_italic));
       await tester.pump();
       check(find.descendant(
         of: find.byType(ZulipAppBar),
         matching: find.text('Channels'))).findsOne();
+      check(hasSearchButton()).isFalse();
 
+      // Direct messages tab: should have title "Direct messages" and no search button
       await tester.tap(find.byIcon(ZulipIcons.two_person));
       await tester.pump();
       check(find.descendant(
         of: find.byType(ZulipAppBar),
         matching: find.text('Direct messages'))).findsOne();
+      check(hasSearchButton()).isFalse();
     });
 
     testWidgets('combined feed', (tester) async {

test/widgets/inbox_test.dart

@@ -4,17 +4,23 @@ import 'package:flutter_checks/flutter_checks.dart';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:zulip/api/model/events.dart';
 import 'package:zulip/api/model/model.dart';
+import 'package:zulip/model/narrow.dart';
 import 'package:zulip/model/store.dart';
+import 'package:zulip/widgets/app_bar.dart';
 import 'package:zulip/widgets/color.dart';
 import 'package:zulip/widgets/home.dart';
 import 'package:zulip/widgets/icons.dart';
 import 'package:zulip/widgets/channel_colors.dart';
+import 'package:zulip/widgets/message_list.dart';
+import 'package:zulip/widgets/page.dart';
 import 'package:zulip/widgets/unread_count_badge.dart';
 
 import '../example_data.dart' as eg;
 import '../flutter_checks.dart';
 import '../model/binding.dart';
 import '../model/test_store.dart';
+import '../test_navigation.dart';
+import 'checks.dart';
 import 'test_app.dart';
 
 /// Repeatedly drags `view` by `moveStep` until `finder` is invisible.
@@ -649,5 +655,32 @@ void main() {
         //   reappear because you unmuted a conversation.)
       });
     });
+
+    testWidgets('tapping search button navigates to search page', (tester) async {
+      // Set up navigation tracking
+      final pushedRoutes = <Route<dynamic>>[];
+      final testNavObserver = TestNavigatorObserver()
+        ..onPushed = (route, prevRoute) => pushedRoutes.add(route);
+
+      // Use existing setupPage function with navigation observer
+      await setupPage(tester,
+        unreadMessages: [],
+        navigatorObserver: testNavObserver);
+
+      // Clear the initial route
+      assert(pushedRoutes.length == 1);
+      pushedRoutes.clear();
+
+      // Tap the search button in the app bar
+      await tester.tap(find.descendant(
+        of: find.byType(ZulipAppBar),
+        matching: find.byIcon(ZulipIcons.search)));
+      await tester.pump();
+
+      // Verify that we navigated to the search page (MessageListPage with KeywordSearchNarrow)
+      check(pushedRoutes).single.isA<WidgetRoute>().page
+        .isA<MessageListPage>()
+        .initNarrow.equals(KeywordSearchNarrow(''));
+    });
   });
 }