reactive async assertions

We have a system where components embedded in a runtime mainly communicate with each other through events. To test these components (or to specifiy its behavior) I’d like to see more assertions that deal with handling a series of events (asynchronously or synchronously).

Here are some examples:

// assert number of events
sut.ShouldRaiseEvent("SomethingHappened").Exacly.Once;
sut.ShouldRaiseEvent("SomethingHappened").AtLeast(5).Times;
sut.ShouldRaiseEvent("SomethingHappened").NotMoreThan(6).Times;

// assert sequence of events
sut.ShouldRaiseEvent("SomethingHappened").FollowedBy("SomethingElseHappened");
sut.ShouldRaiseEvent("SomethingHappened").WithArgs<SomethingEventArgs>(a => a.Foo = "Bar").FollowedBy("SomethingHappened").WithArgs<SomethingEventArgs>(a => a.Foo = "Bar2");
sut.ShouldRaiseEvent("SomethingHappened").AtLeast(5).Times.FollowedBy("SomethingElseHappened");
sut.ShouldRaiseEvent("SomethingHappened").AtLeast(5).Times.FollowedBy("SomethingHappened").WithArgs<SomethingEventArgs>(a => a.Foo = "Bar");

// assert all of the above in an asynchronous fashion (obvoiously you'd often want a timeout here)
await sut.ShouldRaiseEvent("SomethingHappened").Exactly.Once.Within(Timespan.FromSeconds(1));

// but also without a timeout is possible
await sut.ShouldRaiseEvent("SomethingHappened").Exactly.Once.Eventually;

[bitbonk]

I guess it is important that I still can use whatever version of reactive extension I choose in the same Appdomain that the tests run in, because the SUT itself might depend on it.

[dennisdoomen]

Yeah, but it’s a big feature. I welcome Pull Requests though 😏