Added another test

cms/djangoapps/contentstore/tests/test_users.py

+import json
+from .utils import CourseTestCase
+from django.core.urlresolvers import reverse
+
+
+class UsersTestCase(CourseTestCase):
+    def setUp(self):
+        super(UsersTestCase, self).setUp()
+        self.url = reverse("add_user", kwargs={"location": ""})
+
+    def test_empty(self):
+        resp = self.client.post(self.url)
+        self.assertEqual(resp.status_code, 400)
+        content = json.loads(resp.content)
+        self.assertEqual(content["Status"], "Failed")

cms/djangoapps/contentstore/views/user.py

@@ -73,7 +73,7 @@ def add_user(request, location):
     This POST-back view will add a user - specified by email - to the list of editors for
     the specified course
     '''
-    email = request.POST["email"]
+    email = request.POST.get("email")
 
     if not email:
         msg = {