Remove PytestWarnings about collecting test classes

The classes under tests.util are not destined to hold test cases.

Signed-off-by: Ivan Kanakarakis <[email protected]>

tests/util.py

@@ -456,6 +456,8 @@ def register_endpoints(self, backend_names):
 
 
 class TestBackend(BackendModule):
+    __test__ = False
+
     def __init__(self, auth_callback_func, internal_attributes, config, base_url, name):
         super().__init__(auth_callback_func, internal_attributes, base_url, name)
 
@@ -474,6 +476,8 @@ def handle_response(self, context):
 
 
 class TestFrontend(FrontendModule):
+    __test__ = False
+
     def __init__(self, auth_req_callback_func, internal_attributes, config, base_url, name):
         super().__init__(auth_req_callback_func, internal_attributes, base_url, name)
 
@@ -492,6 +496,8 @@ def handle_authn_response(self, context, internal_resp):
 
 
 class TestRequestMicroservice(RequestMicroService):
+    __test__ = False
+
     def __init__(self, *args, **kwargs):
         super().__init__(*args, **kwargs)
 
@@ -503,6 +509,8 @@ def callback(self):
 
 
 class TestResponseMicroservice(ResponseMicroService):
+    __test__ = False
+
     def __init__(self, *args, **kwargs):
         super().__init__(*args, **kwargs)