While running all automatic tests with py.test --app-config test.ini -x as well as running only functional tests with py.test --app-config test.ini -x ringo/tests/functional/ works, running only unit tests with py.test --app-config test.ini -x ringo/tests/unit/ or a single unit test with e.g. py.test --app-config test.ini -x ringo/tests/unit/test_helpers.py fails with an UnboundExecutionError in get_bind().