content: Follow user_settings.twenty_four_hour_time in global times

Fixes zulip#1015.

Author: chrisbobbe

lib/widgets/content.dart

@@ -1501,13 +1501,27 @@ class GlobalTime extends StatelessWidget {
   final GlobalTimeNode node;
   final TextStyle ambientTextStyle;
 
-  static final _dateFormat = intl.DateFormat('EEE, MMM d, y, h:mm a'); // TODO(i18n): localize date
+  static final _format12 =
+    intl.DateFormat('EEE, MMM d, y').addPattern('h:mm aa', ', ');
+  static final _format24 =
+    intl.DateFormat('EEE, MMM d, y').addPattern('Hm', ', ');
+  static final _formatLocaleDefault =
+    intl.DateFormat('EEE, MMM d, y').addPattern('jm', ', ');
 
   @override
   Widget build(BuildContext context) {
+    final store = PerAccountStoreWidget.maybeOf(context);
+    final twentyFourHourTimeMode = store?.userSettings.twentyFourHourTime;
     // Design taken from css for `.rendered_markdown & time` in web,
     //   see zulip:web/styles/rendered_markdown.css .
-    final text = _dateFormat.format(node.datetime.toLocal());
+    // TODO(i18n): localize; see plan with ffi in #45
+    final format = switch (twentyFourHourTimeMode) {
+      TwentyFourHourTimeMode.twelveHour => _format12,
+      TwentyFourHourTimeMode.twentyFourHour => _format24,
+      TwentyFourHourTimeMode.localeDefault => _formatLocaleDefault,
+      null => _formatLocaleDefault, // Not in a per-account context
+    };
+    final text = format.format(node.datetime.toLocal());
     final contentTheme = ContentTheme.of(context);
     return Padding(
       padding: const EdgeInsets.symmetric(horizontal: 2),

test/widgets/content_test.dart

@@ -8,6 +8,7 @@ import 'package:flutter_checks/flutter_checks.dart';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:url_launcher/url_launcher.dart';
 import 'package:zulip/api/core.dart';
+import 'package:zulip/api/model/model.dart';
 import 'package:zulip/model/content.dart';
 import 'package:zulip/model/narrow.dart';
 import 'package:zulip/model/settings.dart';
@@ -139,9 +140,16 @@ void main() {
   Future<void> prepareContent(WidgetTester tester, Widget child, {
     List<NavigatorObserver> navObservers = const [],
     bool wrapWithPerAccountStoreWidget = false,
+    TwentyFourHourTimeMode? twentyFourHourTimeMode
   }) async {
     if (wrapWithPerAccountStoreWidget) {
-      await testBinding.globalStore.add(eg.selfAccount, eg.initialSnapshot());
+      final initialSnapshot = eg.initialSnapshot();
+      if (twentyFourHourTimeMode != null) {
+        initialSnapshot.userSettings.twentyFourHourTime = twentyFourHourTimeMode;
+      }
+      await testBinding.globalStore.add(eg.selfAccount, initialSnapshot);
+    } else {
+      assert(twentyFourHourTimeMode == null);
     }
 
     addTearDown(testBinding.reset);
@@ -1102,11 +1110,45 @@ void main() {
     // the timezone of the environment running these tests. Accept here a wide
     // range of times. See comments in "show dates" test in
     // `test/widgets/message_list_test.dart`.
-    final renderedTextRegexp = RegExp(r'^(Tue, Jan 30|Wed, Jan 31), 2024, \d+:\d\d [AP]M$');
+    final renderedTextRegexp = RegExp(r'^(Tue, Jan 30|Wed, Jan 31), 2024, \d+:\d\d(?: [AP]M)?$');
+    final renderedTextRegexpTwelveHour = RegExp(r'^(Tue, Jan 30|Wed, Jan 31), 2024, \d+:\d\d [AP]M$');
+    final renderedTextRegexpTwentyFourHour = RegExp(r'^(Tue, Jan 30|Wed, Jan 31), 2024, \d+:\d\d$');
 
     testWidgets('smoke', (tester) async {
-      await prepareContent(tester, plainContent('<p>$timeSpanHtml</p>'));
+      await prepareContent(tester,
+        wrapWithPerAccountStoreWidget: false,
+        plainContent('<p>$timeSpanHtml</p>'));
       tester.widget(find.textContaining(renderedTextRegexp));
+
+      // TODO(#1727) test with different locales
+      tester.widget(find.textContaining(renderedTextRegexpTwelveHour));
+    });
+
+    testWidgets('TwentyFourHourTimeMode.twelveHour', (tester) async {
+      await prepareContent(tester,
+        wrapWithPerAccountStoreWidget: true,
+        twentyFourHourTimeMode: TwentyFourHourTimeMode.twelveHour,
+        plainContent('<p>$timeSpanHtml</p>'));
+      check(find.textContaining(renderedTextRegexpTwelveHour)).findsOne();
+    });
+
+    testWidgets('TwentyFourHourTimeMode.twentyFourHour', (tester) async {
+      await prepareContent(tester,
+        wrapWithPerAccountStoreWidget: true,
+        twentyFourHourTimeMode: TwentyFourHourTimeMode.twentyFourHour,
+        plainContent('<p>$timeSpanHtml</p>'));
+      check(find.textContaining(renderedTextRegexpTwentyFourHour)).findsOne();
+    });
+
+    testWidgets('TwentyFourHourTimeMode.localeDefault', (tester) async {
+      await prepareContent(tester,
+        wrapWithPerAccountStoreWidget: true,
+        twentyFourHourTimeMode: TwentyFourHourTimeMode.localeDefault,
+        plainContent('<p>$timeSpanHtml</p>'));
+      tester.widget(find.textContaining(renderedTextRegexp));
+
+      // TODO(#1727) test with different locales
+      check(find.textContaining(renderedTextRegexpTwelveHour)).findsOne();
     });
 
     void testIconAndTextSameColor(String description, String html) {