Do not create a modulestore unnecessarily in tests

cms/djangoapps/contentstore/tests/test_crud.py

 import unittest
 
+from opaque_keys.edx.locator import LocalId
+
 from xmodule import templates
 from xmodule.modulestore import ModuleStoreEnum
 from xmodule.modulestore.tests import persistent_factories
@@ -7,10 +9,9 @@ from xmodule.course_module import CourseDescriptor
 from xmodule.modulestore.django import modulestore, clear_existing_modulestores
 from xmodule.seq_module import SequenceDescriptor
 from xmodule.capa_module import CapaDescriptor
-from opaque_keys.edx.locator import BlockUsageLocator, LocalId
+from xmodule.contentstore.django import _CONTENTSTORE
 from xmodule.modulestore.exceptions import ItemNotFoundError, DuplicateCourseError
 from xmodule.html_module import HtmlDescriptor
-from xmodule.modulestore.tests.django_utils import ModuleStoreTestCase
 
 
 class TemplateTests(unittest.TestCase):
@@ -20,10 +21,22 @@ class TemplateTests(unittest.TestCase):
 
     def setUp(self):
         clear_existing_modulestores()  # redundant w/ cleanup but someone was getting errors
-        self.addCleanup(ModuleStoreTestCase.drop_mongo_collections)
+        self.addCleanup(self._drop_mongo_collections)
         self.addCleanup(clear_existing_modulestores)
         self.split_store = modulestore()._get_modulestore_by_type(ModuleStoreEnum.Type.split)
 
+    @staticmethod
+    def _drop_mongo_collections():
+        """
+        If using a Mongo-backed modulestore & contentstore, drop the collections.
+        """
+        module_store = modulestore()
+        if hasattr(module_store, '_drop_database'):
+            module_store._drop_database()  # pylint: disable=protected-access
+        _CONTENTSTORE.clear()
+        if hasattr(module_store, 'close_connections'):
+            module_store.close_connections()
+
     def test_get_templates(self):
         found = templates.all_templates()
         self.assertIsNotNone(found.get('course'))

common/lib/xmodule/xmodule/modulestore/tests/django_utils.py

@@ -7,6 +7,8 @@ import pytz
 from tempfile import mkdtemp
 from uuid import uuid4
 
+from mock import patch
+
 from django.conf import settings
 from django.contrib.auth.models import User
 from django.test import TestCase
@@ -276,10 +278,14 @@ class ModuleStoreTestCase(TestCase):
         return updated_course
 
     @staticmethod
-    def drop_mongo_collections():
+    @patch('xmodule.modulestore.django.create_modulestore_instance')
+    def drop_mongo_collections(mock_create):
         """
         If using a Mongo-backed modulestore & contentstore, drop the collections.
         """
+        # Do not create the modulestore if it does not exist.
+        mock_create.return_value = None
+
         module_store = modulestore()
         if hasattr(module_store, '_drop_database'):
             module_store._drop_database()  # pylint: disable=protected-access
@@ -302,7 +308,6 @@ class ModuleStoreTestCase(TestCase):
         """
         Flush the ModuleStore.
         """
-
         # Flush the Mongo modulestore
         self.drop_mongo_collections()