There is a new section in the documentation about testing your application using Spincast.

Spincast testing is first and foremost about using a Guice context to run the tests. We developed a custom JUnit runner to make this process very easy. This allows any dependency you need to be injected into your test classes.

Even cooler (in our opinion!), have a look the Integration test example to see how Spincast testing utilities can help you run tests on your actual application. No mocks, no simulation. This approach leads to very trustworthy tests since they are run on your real application, and not on a version where many components have been mocked.