Unfortunately, faking in Silverlight does need the BOS, since the faking implementation is making async calls to the server where the fake store is located.   Since this isn't realistic with an automated test runner, another approach for your unit tests might be to use a disconnected EntityManager with preloaded test data, say from an EntityCacheState.  Some of the code samples take this approach, one being the "Querying" sample at http://drc.ideablade.com/xwiki/bin/view/Documentation/code-sample-querying.

  

I am created an EntityManager in a unit test using the CompositionContext.Fake with the following line of code:

var em = new DomainModelEntityManager(compositionContextName: CompositionContext.Fake.Name);

This works fine when running the silverlight unit test runner from the browser.

However when I run this from Devexpress's Coderush Test runner, I get the white screen of death and in the StatLight test runner, I get the more informed error of:

Is it possible to use faking this way without the Business object server running?  

Thanks

Chris