Fix isToday/isTomorrow day diff for UTC dates across timezone and DST boundaries

.github/workflows/build.yml

@@ -28,8 +28,13 @@ jobs:
       - name: Analyze
         run: dart analyze lib
 
+      - name: Run Bucharest timezone regression
+        env:
+          TZ: Europe/Bucharest
+        run: dart test --tags bucharest_tz
+
       - name: Run tests
-        run: dart test --coverage coverage
+        run: dart test --exclude-tags bucharest_tz --coverage coverage
 
       - name: Coverage
         run: dart run coverage:format_coverage -l -i ./coverage/test/time_test.dart.vm.json -o ./coverage/lcov.info

dart_test.yaml

@@ -0,0 +1,2 @@
+tags:
+  bucharest_tz:

lib/src/extensions.dart

@@ -139,8 +139,8 @@ extension DateTimeTimeExtension on DateTime {
   bool isAtSameMicrosecondAs(DateTime other) => isAtSameMillisecondAs(other) && microsecond == other.microsecond;
 
   static int _calculateDifference(DateTime date) {
-    final now = clock.now();
-    return DateTime(date.year, date.month, date.day).difference(DateTime(now.year, now.month, now.day)).inDays;
+    final now = date.isUtc ? clock.now().toUtc() : clock.now();
+    return date.date.difference(now.date).inDays;
   }
 
   /// Returns a range of dates to [to], exclusive start, inclusive end

pubspec.yaml

@@ -17,3 +17,4 @@ dev_dependencies:
   lints: ^6.0.0
   test: ^1.28.0
   coverage: ^1.15.0
+  timezone: ^0.11.0

test/time_test.dart

@@ -1,9 +1,12 @@
 import 'package:clock/clock.dart';
 import 'package:test/test.dart';
 import 'package:time/time.dart';
+import 'package:timezone/timezone.dart' as tz;
+import 'package:timezone/data/latest.dart' as tz;
 
 void main() {
   final date = DateTime(2000, 1, 1);
+  tz.initializeTimeZones();
 
   group('TimeExtension', () {
     group('Integers', () {
@@ -126,6 +129,43 @@ void main() {
         expect(reconstructed, equals(original));
       });
 
+      test(
+        'handles utc isToday correctly across DST switch',
+        () {
+          final location = tz.getLocation('Europe/Bucharest');
+          tz.setLocalLocation(location);
+          final now = tz.TZDateTime.local(2026, 3, 29, 16);
+
+          withClock(Clock.fixed(now), () {
+            final todayUtc = DateTime.utc(2026, 3, 29);
+            final tomorrowUtc = DateTime.utc(2026, 3, 30);
+
+            // Older implementation of _calculateDifference from time: 2.1.6.
+            int oldCalculateDifference(DateTime date) {
+              final now = clock.now();
+              return DateTime(date.year, date.month, date.day).difference(
+                DateTime(now.year, now.month, now.day),
+              ).inDays;
+            }
+
+            expect(
+              oldCalculateDifference(todayUtc),
+              0,
+              reason: 'Old implementation will mark UTC today as today.',
+            );
+            expect(
+              oldCalculateDifference(tomorrowUtc),
+              0,
+              reason: 'Old implementation will mark UTC tomorrow as today.',
+            );
+
+            expect(todayUtc.isToday, true, reason: 'New implementation handles UTC correctly.');
+            expect(tomorrowUtc.isToday, false, reason: 'New implementation handles UTC correctly.');
+          });
+        },
+        tags: ['bucharest_tz'],
+      );
+
       test('can handle isToday', () {
         final today = date;
         withClock(Clock.fixed(today), () {