We have been running into problems with the new test framework. In some (strange) scenarios seemingly unrelated tests can cause other tests to fail, even across phase boundaries. In this case, the presence of a unit test utilizing DomainClassUnitTestMixin causes an integration test to fail. Switching to @Mock or removing any one of 2 test cases causes the integration test to pass.
This is a really frustrating problem to encounter because it is not always obvious (to me at least) how to tweak the tests to workaround the issue.