TestScheduler, Concat and Do

Question

Hello,

I have a ViewModel that subscribes to a client connection event.
When the event is raised, I serialize the call to 5 client methods using Concat.
When a method returns, I update some progress indicators.

This works fine in production (with real objects). Notice that I do not use ObserveOnScheduler, but rather ObserveOn.
In production, I inject the DispatcherScheduler, and in tests, a TestScheduler.

_Client.Connected.Do(t =>
{
	SetProgress(0, "Starting");
        _Client.Method1()
		.Do(v => SetProgress(20, "Text info"))
        	.Concat<object>(_Client.Method2()
				       .Do(u => SetProgress(40, "Text info")))
		.Concat<object>(_Client.Method3()
				       .Do(u => SetProgress(60, "Text info")))
        	.Concat<object>(_Client.Method4()
				       .Do(u => SetProgress(80, "Text info")))
		.Concat<object>(_Client.Method5()
				       .ObserveOn(dispatcherScheduler)
				       .Do(u =>
				       {
				       		SetProgress(100, "Done!");
				       		//...Update UI consequently
				       })).Subscribe();
}).Subscribe();

Now, I created a Unit Test to verify that when the client connected event is raised, all 5 methods are called and at the
end the progress indicators are set to 100 and Done!

To do this, I used a TestScheduler to setup observables for a fake client. I used Moq to verify that the method were called,
and some assertions at the end to verify the progress indicators.

The code looks like this:

[Test]
public void GetStuffFromClientWhenConnected()
{
	
	_ClientMock.SetupGet(t => t.Connected)
        	   .Returns(_DispatcherScheduler.CreateHotObservable(ReactiveTest.OnNext(1, new EventPattern<EventArgs>(null, null))));

	_ClientMock.Setup(t => t.Method1())
        	   .Returns(_DispatcherScheduler.CreateHotObservable(ReactiveTest.OnNext(3, new FakeData())));

	_ClientMock.Setup(t => t.Method2())
		   .Returns(_DispatcherScheduler.CreateHotObservable(ReactiveTest.OnNext(4, new FakeData())));

	_ClientMock.Setup(t => t.Method3())
        	   .Returns(_DispatcherScheduler.CreateHotObservable(ReactiveTest.OnNext(5, new FakeData())));

	_ClientMock.Setup(t => t.Method4())
        	   .Returns(_DispatcherScheduler.CreateHotObservable(ReactiveTest.OnNext(6, new FakeData())));

	_ClientMock.Setup(t => t.Method5())
		   .Returns(_DispatcherScheduler.CreateHotObservable(ReactiveTest.OnNext(7, new FakeData())));

	var vm = CreateViewModel();

	_DispatcherScheduler.AdvanceTo(8);

	_ClientMock.Verify(t => t.Method1());
	_ClientMock.Verify(t => t.Method2());
	_ClientMock.Verify(t => t.Method3());
	_ClientMock.Verify(t => t.Method4());
	_ClientMock.Verify(t => t.Method5());

	Assert.That(vm.Progress, Is.EqualTo(100));
	Assert.That(vm.ProgressText, Is.EqualTo("Done"));
}

The connected event is raised, the 5 methods are called, but the progress indicators stay at 20, "Text Info".
I wonder why. I registered and raised these events using the TestScheduler.AdvanceTo(8).
It looks like only Method1 completed event was raised.

Any advice?

Regards
Louis-Pierre Beaumont

Answer 1

Well,

I'm going to answer my own question.
I'll give credit to Dave Sexton too, as he wrote part of the answer in a post named Reactive Framework - Chaining

I simply rewrote my big Concat + Do statement, using SelectMany instead.
It now works in both tests and production, and looks much more elegant.