Fluent interface to test INotifyPropertyChanged sample usage

gistfile1.cs

[Test]
public void BusinessUnit_SetToAValue_ExpectedPropertyChangedFired()
{
    //Arrange
    //Act
    //Assert
    _viewModel.Should()
              .FirePropertyChangedOn(s => s.BusinessUnit)
              .When(s => s.BusinessUnit = "Test2");

    _viewModel.Should()
              .FirePropertyChangedOn(s => s.BusinessUnit)
              .HaveValueSetTo(s => s.BusinessUnit, "Test")
              .When(s => s.BusinessUnit = "Test");

    _viewModel.Should()
              .HaveValueSetTo(s => s.BusinessUnit, "Test2")
              .When(s => s.BusinessUnit = "Test2");

    _viewModel.Should()
              .FirePropertyChangedOn(vm => vm.BusinessUnit)
              .SendMessage<ModelChangedMessage>()
              .HaveValueSetTo(vm => vm.BusinessUnit, "Test")
              .When(vm => vm.BusinessUnit = "Test");
}