I would suggest that you provide you own IScheduler
implementation to ObserveOn(IScheduler)
instead of using the ObserveOnDispatcher()
operator. I have used techniques for loading a DispatcherFrame
or a Dispatcher
but the problem is that you are still using a Dispatcher. Eventually I found that you just "fall off the cliff" especially once you have long running background threads involved. Following the guidelines of "No threading in Unit tests" just dont let the dispatcher get near your ViewModels! Your Unit tests will run much, much faster.
A far superior way to deal with this is to inject an interface that gives access to your Dispatcher Scheduler (via the IScheduler
interface). This allows you to substitute in an implementation that exposes the TestScheduler
. You now can control time in your unit test. You can control and validate which actions are marshalled to each scheduler.
This is a really old (pre-Rx) post on 'Unit' testing WPF with Dispatcher calls from early 2009. It seemed like a good idea at the time.
https://leecampbell.com/2009/02/17/responsive-wpf-user-interfaces-part-5/
More information on Testing with Rx and the TestScheduler
is found in my other site on Rx