public void AbstractViewModel_when_validation_is_reset_ErrorsChanged_should_be_raised() { bool raised = false; var sut = new SampleTestViewModel(); sut.ErrorsChanged += (s, e) => { raised = true; }; sut.ValidateUsing( new DataAnnotationValidationService <SampleTestViewModel>(sut), forceIsValidationEnabledTo: true); sut.ResetValidation(); Assert.IsTrue(raised); }