Add tests for has_course

and negative tests for get_course.

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

 # pylint: disable=E0611
 from nose.tools import assert_equals, assert_raises, \
-    assert_not_equals, assert_false, assert_true, assert_greater, assert_is_instance
-from itertools import ifilter
+    assert_not_equals, assert_false, assert_true, assert_greater, assert_is_instance, assert_is_none
 # pylint: enable=E0611
 from path import path
 import pymongo
@@ -157,6 +156,33 @@ class TestMongoModuleStore(unittest.TestCase):
             assert_in(course_key, course_ids)
             course = self.store.get_course(course_key)
             assert_not_none(course)
+            assert_true(self.store.has_course(course_key))
+            mix_cased = SlashSeparatedCourseKey(
+                course_key.org.upper(), course_key.course.upper(), course_key.run.lower()
+            )
+            assert_false(self.store.has_course(mix_cased))
+            assert_true(self.store.has_course(mix_cased, ignore_case=True))
+
+    def test_no_such_course(self):
+        """
+        Test get_course and has_course with ids which don't exist
+        """
+        for course_key in [
+
+            SlashSeparatedCourseKey(*fields)
+            for fields in [
+                ['edX', 'simple', 'no_such_course'], ['edX', 'no_such_course', '2012_Fall'],
+                ['NO_SUCH_COURSE', 'Test_iMport_courSe', '2012_Fall'],
+            ]
+        ]:
+            course = self.store.get_course(course_key)
+            assert_is_none(course)
+            assert_false(self.store.has_course(course_key))
+            mix_cased = SlashSeparatedCourseKey(
+                course_key.org.lower(), course_key.course.upper(), course_key.run.upper()
+            )
+            assert_false(self.store.has_course(mix_cased))
+            assert_false(self.store.has_course(mix_cased, ignore_case=True))
 
     def test_loads(self):
         assert_not_none(