Use clock package

lib/src/streams/timer.dart

@@ -1,5 +1,7 @@
 import 'dart:async';
 
+import 'package:clock/clock.dart';
+
 /// Emits the given value after a specified amount of time.
 ///
 /// ### Example
@@ -25,7 +27,7 @@ class TimerStream<T> extends Stream<T> {
   }
 
   static StreamController<T> _buildController<T>(T value, Duration duration) {
-    final watch = Stopwatch();
+    final watch = clock.stopwatch();
     Timer? timer;
     late StreamController<T> controller;
     Duration? totalElapsed = Duration.zero;

lib/src/transformers/time_interval.dart

@@ -1,10 +1,11 @@
 import 'dart:async';
 
+import 'package:clock/clock.dart';
 import 'package:rxdart/src/utils/forwarding_sink.dart';
 import 'package:rxdart/src/utils/forwarding_stream.dart';
 
 class _TimeIntervalStreamSink<S> extends ForwardingSink<S, TimeInterval<S>> {
-  final _stopwatch = Stopwatch();
+  final _stopwatch = clock.stopwatch();
 
   @override
   void onData(S data) {

lib/src/transformers/timestamp.dart

@@ -1,13 +1,15 @@
 import 'dart:async';
 
+import 'package:clock/clock.dart';
+
 class _TimestampStreamSink<S> implements EventSink<S> {
   final EventSink<Timestamped<S>> _outputSink;
 
   _TimestampStreamSink(this._outputSink);
 
   @override
   void add(S data) {
-    _outputSink.add(Timestamped(DateTime.now(), data));
+    _outputSink.add(Timestamped(clock.now(), data));
   }
 
   @override

pubspec.yaml

@@ -8,6 +8,9 @@ repository: https://github.com/ReactiveX/rxdart
 environment:
   sdk: '>=2.12.0 <3.0.0'
 
+dependencies:
+  clock: ^1.1.0
+
 dev_dependencies:
   build_runner: ^2.1.2
   build_web_compilers: ^3.0.0