nav: Add about-zulip button to menu bar

This is an implementation for issue zulip#1128

This commit includes localizations and tests for the button as well.

assets/l10n/app_en.arb

@@ -23,6 +23,10 @@
   "@switchAccountButton": {
     "description": "Label for main-menu button leading to the choose-account page."
   },
+  "aboutZulipMenuItem": "About Zulip",
+  "@aboutZulipMenuItem": {
+    "description": "Label for the 'About Zulip' option in the main menu."
+  },
   "tryAnotherAccountMessage": "Your account at {url} is taking a while to load.",
   "@tryAnotherAccountMessage": {
     "description": "Message that appears on the loading screen after waiting for some time.",

lib/generated/l10n/zulip_localizations.dart

@@ -139,6 +139,12 @@ abstract class ZulipLocalizations {
   /// **'Switch account'**
   String get switchAccountButton;
 
+  /// Label for the 'About Zulip' option in the main menu.
+  ///
+  /// In en, this message translates to:
+  /// **'About Zulip'**
+  String get aboutZulipMenuItem;
+
   /// Message that appears on the loading screen after waiting for some time.
   ///
   /// In en, this message translates to:

lib/generated/l10n/zulip_localizations_ar.dart

@@ -26,6 +26,9 @@ class ZulipLocalizationsAr extends ZulipLocalizations {
   @override
   String get switchAccountButton => 'Switch account';
 
+  @override
+  String get aboutZulipMenuItem => 'About Zulip';
+
   @override
   String tryAnotherAccountMessage(Object url) {
     return 'Your account at $url is taking a while to load.';

lib/generated/l10n/zulip_localizations_en.dart

@@ -26,6 +26,9 @@ class ZulipLocalizationsEn extends ZulipLocalizations {
   @override
   String get switchAccountButton => 'Switch account';
 
+  @override
+  String get aboutZulipMenuItem => 'About Zulip';
+
   @override
   String tryAnotherAccountMessage(Object url) {
     return 'Your account at $url is taking a while to load.';

lib/generated/l10n/zulip_localizations_fr.dart

@@ -26,6 +26,9 @@ class ZulipLocalizationsFr extends ZulipLocalizations {
   @override
   String get switchAccountButton => 'Switch account';
 
+  @override
+  String get aboutZulipMenuItem => 'About Zulip';
+
   @override
   String tryAnotherAccountMessage(Object url) {
     return 'Your account at $url is taking a while to load.';

lib/generated/l10n/zulip_localizations_ja.dart

@@ -26,6 +26,9 @@ class ZulipLocalizationsJa extends ZulipLocalizations {
   @override
   String get switchAccountButton => 'Switch account';
 
+  @override
+  String get aboutZulipMenuItem => 'About Zulip';
+
   @override
   String tryAnotherAccountMessage(Object url) {
     return 'Your account at $url is taking a while to load.';

lib/generated/l10n/zulip_localizations_pl.dart

@@ -26,6 +26,9 @@ class ZulipLocalizationsPl extends ZulipLocalizations {
   @override
   String get switchAccountButton => 'Switch account';
 
+  @override
+  String get aboutZulipMenuItem => 'About Zulip';
+
   @override
   String tryAnotherAccountMessage(Object url) {
     return 'Your account at $url is taking a while to load.';

lib/generated/l10n/zulip_localizations_ru.dart

@@ -26,6 +26,9 @@ class ZulipLocalizationsRu extends ZulipLocalizations {
   @override
   String get switchAccountButton => 'Switch account';
 
+  @override
+  String get aboutZulipMenuItem => 'About Zulip';
+
   @override
   String tryAnotherAccountMessage(Object url) {
     return 'Your account at $url is taking a while to load.';

lib/widgets/home.dart

@@ -4,6 +4,7 @@ import 'package:flutter/material.dart';
 
 import '../generated/l10n/zulip_localizations.dart';
 import '../model/narrow.dart';
+import 'about_zulip.dart';
 import 'action_sheet.dart';
 import 'app.dart';
 import 'app_bar.dart';
@@ -259,6 +260,7 @@ void _showMainMenu(BuildContext context, {
     // TODO(#1094): Users
     const _MyProfileButton(),
     const _SwitchAccountButton(),
+    const _AboutZulipButton(),
     // TODO(#198): Set my status
     // const SizedBox(height: 8),
     // TODO(#97): Settings
@@ -551,6 +553,23 @@ class _SwitchAccountButton extends _MenuButton {
   }
 }
 
+class _AboutZulipButton extends _MenuButton {
+  const _AboutZulipButton();
+
+  @override
+  IconData get icon => Icons.info;
+
+  @override
+  String label(ZulipLocalizations zulipLocalizations) {
+    return zulipLocalizations.aboutZulipMenuItem;
+  }
+
+  @override
+  void onPressed(BuildContext context) {
+    Navigator.of(context).push(AboutZulipPage.buildRoute(context));
+  }
+}
+
 /// Apply [Transform.scale] to the child widget when tapped, and reset its scale
 /// when released, while animating the transitions.
 class AnimatedScaleOnTap extends StatefulWidget {

test/widgets/home_test.dart

@@ -4,6 +4,7 @@ import 'package:flutter_checks/flutter_checks.dart';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:zulip/api/model/events.dart';
 import 'package:zulip/model/store.dart';
+import 'package:zulip/widgets/about_zulip.dart';
 import 'package:zulip/widgets/app.dart';
 import 'package:zulip/widgets/app_bar.dart';
 import 'package:zulip/widgets/home.dart';
@@ -105,6 +106,9 @@ void main () {
     final combinedFeedMenuIconFinder = find.descendant(
       of: find.byType(BottomSheet),
       matching: find.byIcon(ZulipIcons.message_feed));
+    final aboutZulipMenuIconFinder = find.descendant(
+      of: find.byType(BottomSheet),
+      matching: find.byIcon(Icons.info));
 
     Future<void> tapOpenMenu(WidgetTester tester) async {
       await tester.tap(find.byIcon(ZulipIcons.menu));
@@ -215,6 +219,16 @@ void main () {
       check(find.byType(ProfilePage)).findsOne();
       check(find.text(eg.selfUser.fullName)).findsAny();
     });
+
+    testWidgets('_AboutZulipButton', (tester) async {
+      await prepare(tester);
+      await tapOpenMenu(tester);
+
+      await tester.tap(aboutZulipMenuIconFinder);
+      await tester.pump(Duration.zero); // tap the button
+      await tester.pump(const Duration(milliseconds: 250)); // wait for animation
+      check(find.byType(AboutZulipPage)).findsOne();
+    });
   });
 
   group('_LoadingPlaceholderPage', () {