[test][docker_environments] Code cleanup

beat/core/test/test_docker_environments.py

@@ -52,7 +52,7 @@ class EnvironmentTest(unittest.TestCase):
 
     def tearDown(self):
         self.host.teardown()
-        assert not self.host.containers  # All containers are gone
+        self.assertFalse(self.host.containers)  # All containers are gone
 
     @slow
     def test_package_enumeration(self):