Check descriptor to identify problems that don't support regrading.

common/lib/xmodule/xmodule/capa_module.py

@@ -823,7 +823,7 @@ class CapaModule(CapaFields, XModule):
             {'success' : 'correct' | 'incorrect' | AJAX alert msg string }
 
         Raises NotFoundError if called on a problem that has not yet been
-        answered, or if it's a problem that cannot be regraded.
+        answered, or NotImplementedError if it's a problem that cannot be regraded.
 
         Returns the error messages for exceptions occurring while performing
         the regrading, rather than throwing them.
@@ -835,7 +835,7 @@ class CapaModule(CapaFields, XModule):
         if not self.lcp.supports_regrading():
             event_info['failure'] = 'unsupported'
             self.system.track_function('problem_regrade_fail', event_info)
-            raise NotFoundError('Problem does not support regrading')
+            raise NotImplementedError("Problem's definition does not support regrading")
 
         if not self.done:
             event_info['failure'] = 'unanswered'

common/lib/xmodule/xmodule/tests/test_capa_module.py

@@ -642,13 +642,12 @@ class CapaModuleTest(unittest.TestCase):
             module.regrade_problem()
 
     def test_regrade_problem_not_supported(self):
-        # Simulate that the problem is NOT done
         module = CapaFactory.create(done=True)
 
         # Try to regrade the problem, and get exception
         with patch('capa.capa_problem.LoncapaProblem.supports_regrading') as mock_supports_regrading:
             mock_supports_regrading.return_value = False
-            with self.assertRaises(xmodule.exceptions.NotFoundError):
+            with self.assertRaises(NotImplementedError):
                 module.regrade_problem()
 
     def test_regrade_problem_error(self):
@@ -668,7 +667,7 @@ class CapaModuleTest(unittest.TestCase):
 
             # Expect an AJAX alert message in 'success'
             expected_msg = 'Error: test error'
-            self.assertEqual(expected_msg, result['success'])
+            self.assertEqual(result['success'], expected_msg)
 
             # Expect that the number of attempts is NOT incremented
             self.assertEqual(module.attempts, 1)

lms/djangoapps/courseware/task_queue.py

@@ -297,6 +297,26 @@ def _get_task_completion_message(course_task_log_entry):
 
 ########### Add task-submission methods here:
 
+def _check_arguments_for_regrading(course_id, problem_url):
+    """
+    Do simple checks on the descriptor to confirm that it supports regrading.
+
+    Confirms first that the problem_url is defined (since that's currently typed
+    in).  An ItemNotFoundException is raised if the corresponding module
+    descriptor doesn't exist.  NotImplementedError is returned if the
+    corresponding module doesn't support regrading calls.
+    """
+    descriptor = modulestore().get_instance(course_id, problem_url)
+    supports_regrade = False
+    if hasattr(descriptor,'module_class'):
+        module_class = descriptor.module_class
+        if hasattr(module_class, 'regrade_problem'):
+            supports_regrade = True
+
+    if not supports_regrade:
+        msg = "Specified module does not support regrading."
+        raise NotImplementedError(msg)
+
 
 def submit_regrade_problem_for_student(request, course_id, problem_url, student):
     """
@@ -309,10 +329,8 @@ def submit_regrade_problem_for_student(request, course_id, problem_url, student)
     An exception is thrown if the problem doesn't exist, or if the particular
     problem is already being regraded for this student.
     """
-    # check arguments:  make sure that the problem_url is defined
-    # (since that's currently typed in).  If the corresponding module descriptor doesn't exist,
-    # an exception will be raised.  Let it pass up to the caller.
-    modulestore().get_instance(course_id, problem_url)
+    # check arguments:  let exceptions return up to the caller. 
+    _check_arguments_for_regrading(course_id, problem_url)
 
     task_name = 'regrade_problem'
 
@@ -341,14 +359,11 @@ def submit_regrade_problem_for_all_students(request, course_id, problem_url):
     An exception is thrown if the problem doesn't exist, or if the particular
     problem is already being regraded.
     """
-    # check arguments:  make sure that the problem_url is defined
-    # (since that's currently typed in).  If the corresponding module descriptor doesn't exist,
-    # an exception will be raised.  Let it pass up to the caller.
-    modulestore().get_instance(course_id, problem_url)
-
-    task_name = 'regrade_problem'
+    # check arguments:  let exceptions return up to the caller.
+    _check_arguments_for_regrading(course_id, problem_url)
 
     # check to see if task is already running, and reserve it otherwise
+    task_name = 'regrade_problem'
     course_task_log = _reserve_task(course_id, task_name, problem_url, request.user)
 
     # Submit task: