Exercising the SUT asynchronously
In unit testing, there are times were the SUT has to be exercised asynchronously.
How can we wait for the exercise to complete execution?
- An instance of the SUT can be created on the main thread.
- The main (waiting) thread spins in user mode while starting the exercise of the SUT asynchronously.
- Once the result has been received, the execution continues on the main thread.
- The assertion takes place.
The SpinWait synchronization type contains a method named SpinUntil which works perfect for the described scenario.
// Fixture setup
var sut = new ObjectLocalStorage();
object result = null;
// Exercise system
new Task(() => result = sut.Get(@object)).Start();
SpinWait.SpinUntil(() => result != null);
// Verify outcome
- Once the
Task has been created it is immediately scheduled for execution by calling the
- As long as the unit test runs fast, the waiting thread spins in user mode, which is a good thing.
There is also a SpinUntil overload accepting a TimeSpan timeout.