Handling Async With Specflow for Silverlight

Question

The Silverlight Unit test Framework defines a process for dealing with Async calls (derive test class from Microsoft.Silverlight.Testing.SilverlightTest, add Asynchronous attribute, use EnqueueXXX methods.) Considering the separation that SpecFlow presents between the test class and the steps:

• Can these tools be brought to bear to wait on Silverlight method calls within the test that behave asynchronously (such as making web service calls)?
• If they cannot, what is the guidance for handling this behavior in SpecFlow test files? (Perhaps use an AutoResetEvent that gets tripped in an event handler and wait on it?)

Answer 1

Using an AutoResetEvent won't work because the WaitOne call will block the UI thread. Silverlight makes use of the UI thread even when making async calls to a data services (see this post - Thead is blocked using WebClient and ManualResetEvent) so the WaitOne will actually stop the service from being called.

Answer 2

I know this is probably to late but here goes.

For silverlight async calls you can use the Specflow AsyncContext api

https://github.com/techtalk/SpecFlow/wiki/Testing-Silverlight-Asynchronous-Code

I blogged about this when it was being developed here

http://rburnham.wordpress.com/2011/05/13/testing-silverlight-asynchronous-code-with-specflow/

It helps to explain the concept.