home: Add search button to Inbox page

Fixes-partly: #1854

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 +111,31 @@ 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);
 
+      final findSearchButton = find.descendant(
+        of: find.byType(ZulipAppBar),
+        matching: find.byIcon(ZulipIcons.search));
+
       check(find.descendant(
         of: find.byType(ZulipAppBar),
         matching: find.text('Inbox'))).findsOne();
+      check(findSearchButton).findsOne();
 
       await tester.tap(find.byIcon(ZulipIcons.hash_italic));
       await tester.pump();
       check(find.descendant(
         of: find.byType(ZulipAppBar),
         matching: find.text('Channels'))).findsOne();
+      check(findSearchButton).findsNothing();
 
       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(findSearchButton).findsNothing();
     });
 
     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 +655,27 @@ void main() {
         //   reappear because you unmuted a conversation.)
       });
     });
+
+    testWidgets('tapping search button navigates to search page', (tester) async {
+      final pushedRoutes = <Route<dynamic>>[];
+      final testNavObserver = TestNavigatorObserver()
+        ..onPushed = (route, prevRoute) => pushedRoutes.add(route);
+
+      await setupPage(tester,
+        unreadMessages: [],
+        navigatorObserver: testNavObserver);
+
+      assert(pushedRoutes.length == 1);
+      pushedRoutes.clear();
+
+      await tester.tap(find.descendant(
+        of: find.byType(ZulipAppBar),
+        matching: find.byIcon(ZulipIcons.search)));
+      await tester.pump();
+
+      check(pushedRoutes).single.isA<WidgetRoute>().page
+        .isA<MessageListPage>()
+        .initNarrow.equals(KeywordSearchNarrow(''));
+    });
   });
 }