Add a TestCase mixin for enabling caches in tests

By default, disable all caching in tests, to preserve test independence.
In order to enable caching, inherit from CacheSetupMixin, and specify
which cache configuration is needed.

[EV-32]

common/djangoapps/external_auth/tests/test_shib.py

@@ -23,11 +23,12 @@ from mock import patch
 from nose.plugins.attrib import attr
 from urllib import urlencode
 
+from openedx.core.djangolib.testing.utils import CacheIsolationTestCase
 from student.views import create_account, change_enrollment
 from student.models import UserProfile, CourseEnrollment
 from student.tests.factories import UserFactory
 from xmodule.modulestore.tests.factories import CourseFactory
-from xmodule.modulestore.tests.django_utils import SharedModuleStoreTestCase
+from xmodule.modulestore.tests.django_utils import ModuleStoreTestCase
 from xmodule.modulestore import ModuleStoreEnum
 
 
@@ -76,11 +77,14 @@ def gen_all_identities():
 @attr('shard_3')
 @ddt
 @override_settings(SESSION_ENGINE='django.contrib.sessions.backends.cache')
-class ShibSPTest(SharedModuleStoreTestCase):
+class ShibSPTest(CacheIsolationTestCase):
     """
     Tests for the Shibboleth SP, which communicates via request.META
     (Apache environment variables set by mod_shib)
     """
+
+    ENABLED_CACHES = ['default']
+
     request_factory = RequestFactory()
 
     def setUp(self):
@@ -377,8 +381,23 @@ class ShibSPTest(SharedModuleStoreTestCase):
             self.assertEqual(profile.name, request2.session['ExternalAuthMap'].external_name)
             self.assertEqual(profile.name, identity.get('displayName').decode('utf-8'))
 
+
+@ddt
+@override_settings(SESSION_ENGINE='django.contrib.sessions.backends.cache')
+class ShibSPTestModifiedCourseware(ModuleStoreTestCase):
+    """
+    Tests for the Shibboleth SP which modify the courseware
+    """
+
+    ENABLED_CACHES = ['default', 'mongo_metadata_inheritance', 'loc_cache']
+
+    request_factory = RequestFactory()
+
+    def setUp(self):
+        super(ShibSPTestModifiedCourseware, self).setUp()
+        self.test_user_id = ModuleStoreEnum.UserID.test
+
     @unittest.skipUnless(settings.FEATURES.get('AUTH_USE_SHIB'), "AUTH_USE_SHIB not set")
-    @SharedModuleStoreTestCase.modifies_courseware
     @data(None, "", "shib:https://idp.stanford.edu/")
     def test_course_specific_login_and_reg(self, domain):
         """
@@ -457,7 +476,6 @@ class ShibSPTest(SharedModuleStoreTestCase):
                          '&enrollment_action=enroll')
 
     @unittest.skipUnless(settings.FEATURES.get('AUTH_USE_SHIB'), "AUTH_USE_SHIB not set")
-    @SharedModuleStoreTestCase.modifies_courseware
     def test_enrollment_limit_by_domain(self):
         """
             Tests that the enrollmentDomain setting is properly limiting enrollment to those who have
@@ -525,7 +543,6 @@ class ShibSPTest(SharedModuleStoreTestCase):
                     self.assertFalse(CourseEnrollment.is_enrolled(student, course.id))
 
     @unittest.skipUnless(settings.FEATURES.get('AUTH_USE_SHIB'), "AUTH_USE_SHIB not set")
-    @SharedModuleStoreTestCase.modifies_courseware
     def test_shib_login_enrollment(self):
         """
             A functionality test that a student with an existing shib login