* Added test class for django api unittests and documentation how to use it

Author: Ronny Vedrilla

docs/index.rst

@@ -14,3 +14,4 @@ Contents:
    rest-framework
    form-mutations
    introspection
+   testing

docs/testing.rst

@@ -0,0 +1,60 @@
+Testing API calls with django
+=============================
+
+If you want to unittest your API calls derive your test case from the class `GraphQLTestCase`.
+
+Usage:
+
+.. code:: python
+
+    import json
+
+    from graphene_django.tests.base_test import GraphQLTestCase
+    from my_project.config.schema import schema
+
+    class MyFancyTestCase(GraphQLTestCase):
+        # Here you need to inject your test case's schema
+        GRAPHQL_SCHEMA = schema
+
+        def test_some_query(self):
+            response = self.query(
+                '''
+                query {
+                    myModel {
+                        id
+                        name
+                    }
+                }
+                ''',
+                op_name='myModel'
+            )
+
+            content = json.loads(response.content)
+
+            # This validates the status code and if you get errors
+            self.assertResponseNoErrors(response)
+
+            # Add some more asserts if you like
+            ...
+
+        def test_some_mutation(self):
+            response = self.query(
+                '''
+                mutation myMutation($input: MyMutationInput!) {
+                    myMutation(input: $input) {
+                        my-model {
+                            id
+                            name
+                        }
+                    }
+                }
+                ''',
+                op_name='myMutation',
+                input_data={'my_field': 'foo', 'other_field': 'bar'}
+            )
+
+            # This validates the status code and if you get errors
+            self.assertResponseNoErrors(response)
+
+            # Add some more asserts if you like
+            ...

graphene_django/tests/base_test.py

@@ -0,0 +1,64 @@
+import json
+
+from django.http import HttpResponse
+from django.test import Client
+from django.test import TestCase
+
+
+class GraphQLTestCase(TestCase):
+    """
+    Based on: https://www.sam.today/blog/testing-graphql-with-graphene-django/
+    """
+
+    # URL to graphql endpoint
+    GRAPHQL_URL = '/graphql/'
+    # Here you need to set your graphql schema for the tests
+    GRAPHQL_SCHEMA = None
+
+    @classmethod
+    def setUpClass(cls):
+        super().setUpClass()
+
+        if not cls.GRAPHQL_SCHEMA:
+            raise AttributeError('Variable GRAPHQL_SCHEMA not defined in GraphQLTestCase.')
+
+        cls._client = Client(cls.GRAPHQL_SCHEMA)
+
+    def query(self, query: str, op_name: str = None, input_data: dict = None):
+        """
+        Args:
+            query (string)    - GraphQL query to run
+            op_name (string)  - If the query is a mutation or named query, you must
+                                supply the op_name.  For annon queries ("{ ... }"),
+                                should be None (default).
+            input_data (dict) - If provided, the $input variable in GraphQL will be set
+                                to this value
+
+        Returns:
+            Response object from client
+        """
+        body = {'query': query}
+        if op_name:
+            body['operation_name'] = op_name
+        if input_data:
+            body['variables'] = {'input': input_data}
+
+        resp = self._client.post(self.GRAPHQL_URL, json.dumps(body),
+                                 content_type='application/json')
+        return resp
+
+    def assertResponseNoErrors(self, resp: HttpResponse):
+        """
+        Assert that the call went through correctly. 200 means the syntax is ok, if there are no `errors`,
+        the call was fine.
+        """
+        content = json.loads(resp.content)
+        self.assertEqual(resp.status_code, 200)
+        self.assertNotIn('errors', list(content.keys()))
+
+    def assertResponseHasErrors(self, resp: HttpResponse):
+        """
+        Assert that the call was failing. Take care: Even with errors, GraphQL returns status 200!
+        """
+        content = json.loads(resp.content)
+        self.assertIn('errors', list(content.keys()))