anchor.diff:  
       void doWhileAsync(FakeAsync time, bool doThis()) {
         do {
  +        mockStopwatch.elapsed += const Duration(milliseconds: 1);
           time.elapse(const Duration(milliseconds: 1));
         } while (doThis());
       }
  
positive.code:       }, overrides: <Type, Generator>{
          Platform: () => FakePlatform(operatingSystem: testOs),
          Stdio: () => mockStdio,
        });
  
        testUsingContext('AnsiSpinner works for $testOs (2)', () async {
  
negative.code:     for (String testOs in testPlatforms) {
        testUsingContext('AnsiSpinner works for $testOs (1)', () async {
          bool done = false;
          mockStopwatch = FakeStopwatch();
          FakeAsync().run((FakeAsync time) {
            final AnsiSpinner ansiSpinner = AnsiSpinner(
              timeout: const Duration(hours: 10),
  