Remove the create_user argument to setUp.

Instead, use a class attribute to define test behavior. This allows for
easier addition of new mixins over time.

common/djangoapps/third_party_auth/tests/utils.py

@@ -26,9 +26,11 @@ class ThirdPartyOAuthTestMixin(ThirdPartyAuthTestMixin):
     access_token = "test_access_token"
     client_id = "test_client_id"
 
-    def setUp(self, create_user=True):
+    CREATE_USER = True
+
+    def setUp(self):
         super(ThirdPartyOAuthTestMixin, self).setUp()
-        if create_user:
+        if self.CREATE_USER:
             self.user = UserFactory()
             UserSocialAuth.objects.create(user=self.user, provider=self.BACKEND, uid=self.social_uid)
         self.oauth_client = self._create_client()

common/djangoapps/util/tests/test_keyword_sub_utils.py

@@ -17,8 +17,10 @@ from util import keyword_substitution as Ks
 class KeywordSubTest(ModuleStoreTestCase):
     """ Tests for the keyword substitution feature """
 
+    CREATE_USER = False
+
     def setUp(self):
-        super(KeywordSubTest, self).setUp(create_user=False)
+        super(KeywordSubTest, self).setUp()
         self.user = UserFactory.create(
             email="testuser@edx.org",
             username="testuser",

common/djangoapps/util/tests/test_milestones_helpers.py

@@ -18,11 +18,13 @@ class MilestonesHelpersTestCase(ModuleStoreTestCase):
     Main test suite for Milestones API client library
     """
 
+    CREATE_USER = False
+
     def setUp(self):
         """
         Test case scaffolding
         """
-        super(MilestonesHelpersTestCase, self).setUp(create_user=False)
+        super(MilestonesHelpersTestCase, self).setUp()
         self.course = CourseFactory.create(
             metadata={
                 'entrance_exam_enabled': True,

common/djangoapps/util/tests/test_organizations_helpers.py

@@ -14,11 +14,13 @@ class OrganizationsHelpersTestCase(ModuleStoreTestCase):
     Main test suite for Organizations API client library
     """
 
+    CREATE_USER = False
+
     def setUp(self):
         """
         Test case scaffolding
         """
-        super(OrganizationsHelpersTestCase, self).setUp(create_user=False)
+        super(OrganizationsHelpersTestCase, self).setUp()
         self.course = CourseFactory.create()
 
         self.organization = {