Mocking a C# timer with Moq

Question

I'm attempting to create a WPF MVVM View Model that has a dependency injected System.Timing.Timer, and wish to test the view model with Moq.

I wrote a thin wrapper around the Timer class that has a interface ITimer, but am unsure of the best way to really test the timer's contribution to the class. Is there a good way to 'force' a mock elapsed event? Does somebody else have a better technique?

Answer 1

You should test your code in isolation. Otherwise you don't know whether your code behaves as expected, or there is some side-effect in external dependency. Thus creating mockable wrappers for external resources (configuration files, timers, etc) is the only way you can separate your SUT from external code.