MIT CCX: Use CCX Keys: further revisions in response to code review

only require ccx-keys once

get_current_ccx will now expect a CourseKey instance as its argument, and will raise a value error if this expectation is not met.

document reason for local import

add special methods to pass attribute setting and deletion through to the wrapped modulestore

add __setattr__ and __delattr__ per code review, update __init__ to work with new methods

style change per code review

clean up context manager usage as recommended by code review

remove unused code and imports

convert modulestore type tests to use the `get_modulestore_type` api, remove unused imports

code quality: add docstrings

increase coverage for utils tests

fix bug found in testing.

increase test coverage on modulestore wrapper

code quality fixes

code-quality: ignore import error, but mark site for future consideration

lms/djangoapps/dashboard/tests/test_sysadmin.py

@@ -32,8 +32,6 @@ from student.tests.factories import UserFactory
 from xmodule.modulestore.django import modulestore
 from xmodule.modulestore.tests.django_utils import ModuleStoreTestCase
 from xmodule.modulestore.tests.mongo_connection import MONGO_PORT_NUM, MONGO_HOST
-from xmodule.modulestore.xml import XMLModuleStore
-from ccx.modulestore import CCXModulestoreWrapper
 
 
 TEST_MONGODB_LOG = {
@@ -316,12 +314,9 @@ class TestSysadmin(SysadminBaseTestCase):
         # Create git loaded course
         response = self._add_edx4edx()
 
-        def_ms = check_ms = modulestore()
-        # if the modulestore is wrapped by CCX, unwrap it for testing purposes
-        if isinstance(check_ms, CCXModulestoreWrapper):
-            check_ms = check_ms._modulestore
+        def_ms = modulestore()
 
-        self.assertIn('xml', str(check_ms.__class__))
+        self.assertEqual('xml', def_ms.get_modulestore_type(None))
         course = def_ms.courses.get('{0}/edx4edx_lite'.format(
             os.path.abspath(settings.DATA_DIR)), None)
         self.assertIsNotNone(course)
@@ -465,7 +460,7 @@ class TestSysAdminMongoCourseImport(SysadminBaseTestCase):
         self._mkdir(getattr(settings, 'GIT_REPO_DIR'))
 
         def_ms = modulestore()
-        self.assertFalse(isinstance(def_ms, XMLModuleStore))
+        self.assertFalse('xml' == def_ms.get_modulestore_type(None))
 
         self._add_edx4edx()
         course = def_ms.get_course(SlashSeparatedCourseKey('MITx', 'edx4edx', 'edx4edx'))