Use the Django TestCase's Client (#1084)

* Use the Django Client test utility instance that Django provides with its TestCase class. This allows GraphQL tests to make use of the stateful client methods like login()

* Add missing test case initializer call

* Don't break backward compability

* Add test for pending deprecation warning on GraphQLTestCase._client

Co-authored-by: Tom Nightingale <tom@tnightingale.com>

graphene_django/tests/test_utils.py

@@ -51,7 +51,9 @@ def runTest(self):
             pass
 
     tc = TestClass()
+    tc._pre_setup()
     tc.setUpClass()
+
     tc.query("query { }", op_name="QueryName")
     body = json.loads(post_mock.call_args.args[1])
     # `operationName` field from https://graphql.org/learn/serving-over-http/#post-request

graphene_django/utils/testing.py

@@ -1,6 +1,7 @@
 import json
+import warnings
 
-from django.test import TestCase, Client
+from django.test import Client, TestCase
 
 DEFAULT_GRAPHQL_URL = "/graphql/"
 
@@ -68,12 +69,6 @@ class GraphQLTestCase(TestCase):
     # URL to graphql endpoint
     GRAPHQL_URL = DEFAULT_GRAPHQL_URL
 
-    @classmethod
-    def setUpClass(cls):
-        super(GraphQLTestCase, cls).setUpClass()
-
-        cls._client = Client()
-
     def query(self, query, op_name=None, input_data=None, variables=None, headers=None):
         """
         Args:
@@ -99,10 +94,19 @@ def query(self, query, op_name=None, input_data=None, variables=None, headers=No
             input_data=input_data,
             variables=variables,
             headers=headers,
-            client=self._client,
+            client=self.client,
             graphql_url=self.GRAPHQL_URL,
         )
 
+    @property
+    def _client(self):
+        warnings.warn(
+            "Using `_client` is deprecated in favour of `client`.",
+            PendingDeprecationWarning,
+            stacklevel=2,
+        )
+        return self.client
+
     def assertResponseNoErrors(self, resp, msg=None):
         """
         Assert that the call went through correctly. 200 means the syntax is ok, if there are no `errors`,

graphene_django/utils/tests/test_testing.py

@@ -0,0 +1,24 @@
+import pytest
+
+from .. import GraphQLTestCase
+from ...tests.test_types import with_local_registry
+
+
+@with_local_registry
+def test_graphql_test_case_deprecated_client():
+    """
+    Test that `GraphQLTestCase._client`'s should raise pending deprecation warning.
+    """
+
+    class TestClass(GraphQLTestCase):
+        GRAPHQL_SCHEMA = True
+
+        def runTest(self):
+            pass
+
+    tc = TestClass()
+    tc._pre_setup()
+    tc.setUpClass()
+
+    with pytest.warns(PendingDeprecationWarning):
+        tc._client