public void Support_Cancelation()
{
var events = Substitute.For<IEventAggregator>();
var sut = new BusyViewModel(events);
const string taskName = nameof(Support_Cancelation);
var msg = new StartTaskMessage((c, p) => Enumerable.Range(1, 10).ToList().ForEach(i =>
{
Thread.Sleep(10);
p.Report(i * 10);
c.ThrowIfCancellationRequested();
}), taskName);
var task = sut.Handle(msg);
sut.IsBusy.Should().BeTrue();
sut.WaitingFor.Should().Be($"Waiting for '{taskName}'...");
sut.Cancel();
sut.WaitingFor.Should().Be($"Cancelling '{taskName}'...");
sut.IsIndeterminate.Should().BeTrue();
sut.IsBusy.Should().BeTrue();
// ReSharper disable once MethodSupportsCancellation
task.Wait();
sut.IsBusy.Should().BeFalse();
events.Received().PublishOnUIThread(TaskState.Canceled);
}