Add factory for CourseTaskLog.

Add unit tests for regrading at courseware level (task and task_queue).

lms/djangoapps/courseware/task_queue.py

@@ -16,6 +16,10 @@ from xmodule.modulestore.django import modulestore
 log = logging.getLogger(__name__)
 
 
+class AlreadyRunningError(Exception):
+    pass
+
+
 def get_running_course_tasks(course_id):
     """
     Returns a query of CourseTaskLog objects of running tasks for a given course.
@@ -85,7 +89,7 @@ def _reserve_task(course_id, task_name, task_args, requester, student=None):
     """
 
     if _task_is_running(course_id, task_name, task_args, student):
-        raise Exception("requested task is already running")
+        raise AlreadyRunningError("requested task is already running")
 
     # Create log entry now, so that future requests won't
     tasklog_args = {'course_id': course_id,
@@ -157,7 +161,7 @@ def _update_course_task_log(course_task_log_entry, task_result):
                                  total=returned_result['total'],
                                  action_name=returned_result['action_name'])
             output['message'] = message
-            log.info("task progress: {0}".format(message))
+            log.info("task progress: %s", message)
         else:
             log.info("still making progress... ")
         output['task_progress'] = returned_result
@@ -165,7 +169,7 @@ def _update_course_task_log(course_task_log_entry, task_result):
     elif result_state == 'SUCCESS':
         output['task_progress'] = returned_result
         course_task_log_entry.task_progress = json.dumps(returned_result)
-        log.info("task succeeded: {0}".format(returned_result))
+        log.info("task succeeded: %s", returned_result)
         entry_needs_saving = True
 
     elif result_state == 'FAILURE':
@@ -175,13 +179,23 @@ def _update_course_task_log(course_task_log_entry, task_result):
         entry_needs_saving = True
         task_progress = {'exception': type(exception).__name__, 'message': str(exception.message)}
         output['message'] = exception.message
-        log.warning("background task (%s) failed: %s %s".format(task_id, returned_result, traceback))
+        log.warning("background task (%s) failed: %s %s", task_id, returned_result, traceback)
         if result_traceback is not None:
             output['task_traceback'] = result_traceback
             task_progress['traceback'] = result_traceback
         course_task_log_entry.task_progress = json.dumps(task_progress)
         output['task_progress'] = task_progress
 
+    elif result_state == 'REVOKED':
+        # on revocation, the result's result doesn't contain anything
+        entry_needs_saving = True
+        message = 'Task revoked before running'
+        output['message'] = message
+        log.warning("background task (%s) revoked.", task_id)
+        task_progress = {'message': message}
+        course_task_log_entry.task_progress = json.dumps(task_progress)
+        output['task_progress'] = task_progress
+
     # always update the entry if the state has changed:
     if result_state != course_task_log_entry.task_state:
         course_task_log_entry.task_state = result_state
@@ -308,7 +322,7 @@ def _check_arguments_for_regrading(course_id, problem_url):
     """
     descriptor = modulestore().get_instance(course_id, problem_url)
     supports_regrade = False
-    if hasattr(descriptor,'module_class'):
+    if hasattr(descriptor, 'module_class'):
         module_class = descriptor.module_class
         if hasattr(module_class, 'regrade_problem'):
             supports_regrade = True

lms/djangoapps/courseware/tests/factories.py

@@ -10,6 +10,8 @@ from student.tests.factories import CourseEnrollmentAllowedFactory as StudentCou
 from student.tests.factories import RegistrationFactory as StudentRegistrationFactory
 from courseware.models import StudentModule, XModuleContentField, XModuleSettingsField
 from courseware.models import XModuleStudentInfoField, XModuleStudentPrefsField
+from courseware.models import CourseTaskLog
+
 
 from xmodule.modulestore import Location
 from pytz import UTC
@@ -84,3 +86,16 @@ class StudentInfoFactory(DjangoModelFactory):
     field_name = 'existing_field'
     value = json.dumps('old_value')
     student = SubFactory(UserFactory)
+
+
+class CourseTaskLogFactory(DjangoModelFactory):
+    FACTORY_FOR = CourseTaskLog
+
+    task_name = 'regrade_problem'
+    course_id = "MITx/999/Robot_Super_Course"
+    student = SubFactory(UserFactory)
+    task_args = None
+    task_id = None
+    task_state = "QUEUED"
+    task_progress = None
+    requester = SubFactory(UserFactory)

lms/djangoapps/courseware/tests/test_task_queue.py

@@ -0,0 +1,278 @@
+"""
+Test for LMS courseware background task queue management
+"""
+import logging
+import json
+from mock import Mock, patch
+from uuid import uuid4
+
+from django.utils.datastructures import MultiValueDict
+from django.test.testcases import TestCase
+
+from xmodule.modulestore.exceptions import ItemNotFoundError
+
+from courseware.tests.factories import UserFactory, CourseTaskLogFactory
+from courseware.task_queue import (get_running_course_tasks, 
+                                   course_task_log_status,
+                                   AlreadyRunningError,
+                                   submit_regrade_problem_for_all_students, 
+                                   submit_regrade_problem_for_student,
+                                   submit_reset_problem_attempts_for_all_students,
+                                   submit_delete_problem_state_for_all_students)
+
+
+log = logging.getLogger("mitx." + __name__)
+
+
+TEST_FAILURE_MESSAGE = 'task failed horribly'
+
+
+class TaskQueueTestCase(TestCase):
+    """
+    Check that background tasks are properly queued and report status.
+    """
+    student = None
+    instructor = None
+    problem_url = None
+
+    def setUp(self):
+        self.student = UserFactory.create(username="student", email="student@edx.org")
+        self.instructor = UserFactory.create(username="instructor", email="student@edx.org")
+        self.problem_url = TaskQueueTestCase.problem_location("test_urlname")
+
+    @staticmethod
+    def problem_location(problem_url_name):
+        """
+        Create an internal location for a test problem.
+        """
+        if "i4x:" in problem_url_name:
+            return problem_url_name
+        else:
+            return "i4x://{org}/{number}/problem/{problem_url_name}".format(org='edx',
+                                                                            number='1.23x',
+                                                                            problem_url_name=problem_url_name)
+
+    def _create_entry(self, task_state="QUEUED", task_progress=None, student=None):
+        task_id = str(uuid4())
+        progress_json = json.dumps(task_progress)
+        course_task_log = CourseTaskLogFactory.create(student=student,
+                                                      requester=self.instructor,
+                                                      task_args=self.problem_url,
+                                                      task_id=task_id,
+                                                      task_state=task_state,
+                                                      task_progress=progress_json)
+        return course_task_log
+
+    def _create_failure_entry(self):
+        # view task entry for task failure
+        progress = {'message': TEST_FAILURE_MESSAGE,
+                    'exception': 'RandomCauseError',
+                    }
+        return self._create_entry(task_state="FAILURE", task_progress=progress)
+
+    def _create_success_entry(self, student=None):
+        return self._create_progress_entry(student=None, task_state="SUCCESS")
+
+    def _create_progress_entry(self, student=None, task_state="PROGRESS"):
+        # view task entry for task failure
+        progress = {'attempted': 3,
+                    'updated': 2,
+                    'total': 10,
+                    'action_name': 'regraded',
+                    'message': 'some random string that should summarize the other info',
+                    }
+        return self._create_entry(task_state=task_state, task_progress=progress, student=student)
+
+    def test_fetch_running_tasks(self):
+        # when fetching running tasks, we get all running tasks, and only running tasks
+        failure_task_ids = [(self._create_failure_entry()).task_id for _ in range(1, 4)]
+        entry = self._create_failure_entry()
+        failure_task_ids.append(entry.task_id)
+        course_id = entry.course_id  # get course_id used by the factory
+        success_task_ids = [(self._create_success_entry()).task_id for _ in range(1, 5)]
+        progress_task_ids = [(self._create_progress_entry()).task_id for _ in range(1, 5)]
+        task_ids = [course_task_log.task_id for course_task_log in get_running_course_tasks(course_id)]
+        self.assertEquals(len(task_ids), len(progress_task_ids))
+        for task_id in task_ids:
+            self.assertTrue(task_id in progress_task_ids)
+            self.assertFalse(task_id in success_task_ids)
+            self.assertFalse(task_id in failure_task_ids)
+
+    def test_course_task_log_status_by_post(self):
+        # fetch status for existing tasks: by arg is tested elsewhere,
+        # so test by POST arg
+        course_task_log = self._create_failure_entry()
+        task_id = course_task_log.task_id
+        request = Mock()
+        request.POST = {}
+        request.POST['task_id'] = task_id
+        response = course_task_log_status(request)
+        output = json.loads(response.content)
+        self.assertEquals(output['task_id'], task_id)
+
+    def test_course_task_log_status_list_by_post(self):
+        # Fetch status for existing tasks: by arg is tested elsewhere,
+        # so test here by POST arg list, as if called from ajax.
+        # Note that ajax does something funny with the marshalling of
+        # list data, so the key value has "[]" appended to it.
+        task_ids = [(self._create_failure_entry()).task_id for _ in range(1, 5)]
+        request = Mock()
+        request.POST = MultiValueDict({'task_ids[]': task_ids})
+        response = course_task_log_status(request)
+        output = json.loads(response.content)
+        for task_id in task_ids:
+            self.assertEquals(output[task_id]['task_id'], task_id)
+
+    def test_initial_failure(self):
+        course_task_log = self._create_failure_entry()
+        task_id = course_task_log.task_id
+        response = course_task_log_status(Mock(), task_id=task_id)
+        output = json.loads(response.content)
+        self.assertEquals(output['task_id'], task_id)
+        self.assertEquals(output['task_state'], "FAILURE")
+        self.assertFalse(output['in_progress'])
+        self.assertEquals(output['message'], TEST_FAILURE_MESSAGE)
+
+    def test_initial_success(self):
+        course_task_log = self._create_success_entry()
+        task_id = course_task_log.task_id
+        response = course_task_log_status(Mock(), task_id=task_id)
+        output = json.loads(response.content)
+        self.assertEquals(output['task_id'], task_id)
+        self.assertEquals(output['task_state'], "SUCCESS")
+        self.assertFalse(output['in_progress'])
+
+    def test_update_progress_to_progress(self):
+        # view task entry for task in progress
+        course_task_log = self._create_progress_entry()
+        task_id = course_task_log.task_id
+        mock_result = Mock()
+        mock_result.task_id = task_id
+        mock_result.state = "PROGRESS"
+        mock_result.result = {'attempted': 5,
+                              'updated': 4,
+                              'total': 10,
+                              'action_name': 'regraded'}
+        with patch('celery.result.AsyncResult.__new__') as mock_result_ctor:
+            mock_result_ctor.return_value = mock_result
+            response = course_task_log_status(Mock(), task_id=task_id)
+        output = json.loads(response.content)
+        self.assertEquals(output['task_id'], task_id)
+        self.assertEquals(output['task_state'], "PROGRESS")
+        self.assertTrue(output['in_progress'])
+        # self.assertEquals(output['message'], )
+
+    def test_update_progress_to_failure(self):
+        # view task entry for task in progress that later fails
+        course_task_log = self._create_progress_entry()
+        task_id = course_task_log.task_id
+        mock_result = Mock()
+        mock_result.task_id = task_id
+        mock_result.state = "FAILURE"
+        mock_result.result = NotImplementedError("This task later failed.")
+        mock_result.traceback = "random traceback"
+        with patch('celery.result.AsyncResult.__new__') as mock_result_ctor:
+            mock_result_ctor.return_value = mock_result
+            response = course_task_log_status(Mock(), task_id=task_id)
+        output = json.loads(response.content)
+        self.assertEquals(output['task_id'], task_id)
+        self.assertEquals(output['task_state'], "FAILURE")
+        self.assertFalse(output['in_progress'])
+        self.assertEquals(output['message'], "This task later failed.")
+
+    def test_update_progress_to_revoked(self):
+        # view task entry for task in progress that later fails
+        course_task_log = self._create_progress_entry()
+        task_id = course_task_log.task_id
+        mock_result = Mock()
+        mock_result.task_id = task_id
+        mock_result.state = "REVOKED"
+        with patch('celery.result.AsyncResult.__new__') as mock_result_ctor:
+            mock_result_ctor.return_value = mock_result
+            response = course_task_log_status(Mock(), task_id=task_id)
+        output = json.loads(response.content)
+        self.assertEquals(output['task_id'], task_id)
+        self.assertEquals(output['task_state'], "REVOKED")
+        self.assertFalse(output['in_progress'])
+        self.assertEquals(output['message'], "Task revoked before running")
+
+    def _get_output_for_task_success(self, attempted, updated, total, student=None):
+        # view task entry for task in progress
+        course_task_log = self._create_progress_entry(student)
+        task_id = course_task_log.task_id
+        mock_result = Mock()
+        mock_result.task_id = task_id
+        mock_result.state = "SUCCESS"
+        mock_result.result = {'attempted': attempted,
+                              'updated': updated,
+                              'total': total,
+                              'action_name': 'regraded'}
+        with patch('celery.result.AsyncResult.__new__') as mock_result_ctor:
+            mock_result_ctor.return_value = mock_result
+            response = course_task_log_status(Mock(), task_id=task_id)
+        output = json.loads(response.content)
+        return task_id, output
+
+    def test_update_progress_to_success(self):
+        task_id, output = self._get_output_for_task_success(10, 8, 10)
+        self.assertEquals(output['task_id'], task_id)
+        self.assertEquals(output['task_state'], "SUCCESS")
+        self.assertFalse(output['in_progress'])
+
+    def test_success_messages(self):
+        _, output = self._get_output_for_task_success(0, 0, 10)
+        self.assertTrue("Unable to find any students with submissions to be regraded" in output['message'])
+        self.assertFalse(output['succeeded'])
+
+        _, output = self._get_output_for_task_success(10, 0, 10)
+        self.assertTrue("Problem failed to be regraded for any of 10 students " in output['message'])
+        self.assertFalse(output['succeeded'])
+
+        _, output = self._get_output_for_task_success(10, 8, 10)
+        self.assertTrue("Problem regraded for 8 of 10 students" in output['message'])
+        self.assertFalse(output['succeeded'])
+
+        _, output = self._get_output_for_task_success(10, 10, 10)
+        self.assertTrue("Problem successfully regraded for 10 students" in output['message'])
+        self.assertTrue(output['succeeded'])
+
+        _, output = self._get_output_for_task_success(0, 0, 1, student=self.student)
+        self.assertTrue("Unable to find submission to be regraded for student" in output['message'])
+        self.assertFalse(output['succeeded'])
+
+        _, output = self._get_output_for_task_success(1, 0, 1, student=self.student)
+        self.assertTrue("Problem failed to be regraded for student" in output['message'])
+        self.assertFalse(output['succeeded'])
+
+        _, output = self._get_output_for_task_success(1, 1, 1, student=self.student)
+        self.assertTrue("Problem successfully regraded for student" in output['message'])
+        self.assertTrue(output['succeeded'])
+
+    def test_submit_nonexistent_modules(self):
+        # confirm that a regrade of a non-existent module returns an exception
+        # (Note that it is easier to test a non-regradable module in test_tasks,
+        # where we are creating real modules.
+        problem_url = self.problem_url
+        course_id = "something else"
+        request = None
+        with self.assertRaises(ItemNotFoundError):
+            submit_regrade_problem_for_student(request, course_id, problem_url, self.student)
+        with self.assertRaises(ItemNotFoundError):
+            submit_regrade_problem_for_all_students(request, course_id, problem_url)
+        with self.assertRaises(ItemNotFoundError):
+            submit_reset_problem_attempts_for_all_students(request, course_id, problem_url)
+        with self.assertRaises(ItemNotFoundError):
+            submit_delete_problem_state_for_all_students(request, course_id, problem_url)
+
+    def test_submit_when_running(self):
+        # get exception when trying to submit a task that is already running
+        course_task_log = self._create_progress_entry()
+        problem_url = course_task_log.task_args
+        course_id = course_task_log.course_id
+        # requester doesn't have to be the same when determining if a task is already running
+        request = Mock()
+        request.user = self.student
+        with self.assertRaises(AlreadyRunningError):
+            # just skip making the argument check, so we don't have to fake it deeper down
+            with patch('courseware.task_queue._check_arguments_for_regrading'):
+                submit_regrade_problem_for_all_students(request, course_id, problem_url)

lms/djangoapps/courseware/tests/test_tasks.py

@@ -0,0 +1,340 @@
+'''
+Test for LMS courseware background tasks
+'''
+import logging
+import json
+from mock import Mock, patch
+
+from django.contrib.auth.models import User
+from django.core.urlresolvers import reverse
+from django.test.utils import override_settings
+
+from capa.tests.response_xml_factory import OptionResponseXMLFactory, CodeResponseXMLFactory
+from xmodule.modulestore.django import modulestore
+from xmodule.modulestore.tests.factories import CourseFactory, ItemFactory
+from xmodule.modulestore.tests.django_utils import ModuleStoreTestCase
+from xmodule.modulestore.exceptions import ItemNotFoundError
+from student.tests.factories import CourseEnrollmentFactory, UserFactory, AdminFactory
+
+from courseware.model_data import StudentModule
+from courseware.task_queue import (submit_regrade_problem_for_all_students, 
+                                   submit_regrade_problem_for_student,
+                                   course_task_log_status)
+from courseware.tests.tests import LoginEnrollmentTestCase, TEST_DATA_MONGO_MODULESTORE
+
+
+log = logging.getLogger("mitx." + __name__)
+
+
+TEST_COURSE_ORG = 'edx'
+TEST_COURSE_NAME = 'Test Course'
+TEST_COURSE_NUMBER = '1.23x'
+TEST_SECTION_NAME = "Problem"
+
+
+@override_settings(MODULESTORE=TEST_DATA_MONGO_MODULESTORE)
+class TestRegradingBase(LoginEnrollmentTestCase, ModuleStoreTestCase):
+    """
+    Test that all students' answers to a problem can be regraded after the
+    definition of the problem has been redefined.
+    """
+    course = None
+    current_user = None
+
+    def initialize_course(self):
+        """Create a course in the store, with a chapter and section."""
+        self.module_store = modulestore()
+
+        # Create the course
+        self.course = CourseFactory.create(org=TEST_COURSE_ORG,
+                                           number=TEST_COURSE_NUMBER,
+                                           display_name=TEST_COURSE_NAME)
+
+        # Add a chapter to the course
+        chapter = ItemFactory.create(parent_location=self.course.location,
+                                     display_name=TEST_SECTION_NAME)
+
+        # add a sequence to the course to which the problems can be added
+        self.problem_section = ItemFactory.create(parent_location=chapter.location,
+                                                  template='i4x://edx/templates/sequential/Empty',
+                                                  display_name=TEST_SECTION_NAME)
+
+    @staticmethod
+    def get_user_email(username):
+        return '{0}@test.com'.format(username)
+
+    @staticmethod
+    def get_user_password(username):
+        return 'test'
+
+    def login_username(self, username):
+        self.login(TestRegradingBase.get_user_email(username), TestRegradingBase.get_user_password(username))
+        self.current_user = username
+
+    def _create_user(self, username, is_staff=False):
+        email = TestRegradingBase.get_user_email(username)
+        if (is_staff):
+            AdminFactory.create(username=username, email=email)
+        else:
+            UserFactory.create(username=username, email=email)
+        thisuser = User.objects.get(username=username)
+        CourseEnrollmentFactory.create(user=thisuser, course_id=self.course.id)
+        return thisuser
+
+    def create_instructor(self, username):
+        return self._create_user(username, is_staff=True)
+
+    def create_student(self, username):
+        return self._create_user(username, is_staff=False)
+
+    @staticmethod
+    def problem_location(problem_url_name):
+        """
+        Create an internal location for a test problem.
+        """
+        if "i4x:" in problem_url_name:
+            return problem_url_name
+        else:
+            return "i4x://{org}/{number}/problem/{problem_url_name}".format(org=TEST_COURSE_ORG,
+                                                                            number=TEST_COURSE_NUMBER,
+                                                                            problem_url_name=problem_url_name)
+
+    def define_option_problem(self, problem_url_name):
+        """Create the problem definition so the answer is Option 1"""
+        factory = OptionResponseXMLFactory()
+        factory_args = {'question_text': 'The correct answer is Option 1',
+                        'options': ['Option 1', 'Option 2'],
+                        'correct_option': 'Option 1',
+                        'num_responses': 2}
+        problem_xml = factory.build_xml(**factory_args)
+        ItemFactory.create(parent_location=self.problem_section.location,
+                           template="i4x://edx/templates/problem/Blank_Common_Problem",
+                           display_name=str(problem_url_name),
+                           data=problem_xml)
+
+    def redefine_option_problem(self, problem_url_name):
+        """Change the problem definition so the answer is Option 2"""
+        factory = OptionResponseXMLFactory()
+        factory_args = {'question_text': 'The correct answer is Option 2',
+                        'options': ['Option 1', 'Option 2'],
+                        'correct_option': 'Option 2',
+                        'num_responses': 2}
+        problem_xml = factory.build_xml(**factory_args)
+        location = TestRegrading.problem_location(problem_url_name)
+        self.module_store.update_item(location, problem_xml)
+
+    def render_problem(self, username, problem_url_name):
+        """
+        Use ajax interface to request html for a problem.
+        """
+        # make sure that the requested user is logged in, so that the ajax call works
+        # on the right problem:
+        if self.current_user != username:
+            self.login_username(username)
+        # make ajax call:
+        modx_url = reverse('modx_dispatch',
+                            kwargs={
+                                'course_id': self.course.id,
+                                'location': TestRegrading.problem_location(problem_url_name),
+                                'dispatch': 'problem_get', })
+        resp = self.client.post(modx_url, {})
+        return resp
+
+    def submit_student_answer(self, username, problem_url_name, responses):
+        """
+        Use ajax interface to submit a student answer.
+
+        Assumes the input list of responses has two values.
+        """
+        def get_input_id(response_id):
+            return 'input_i4x-{0}-{1}-problem-{2}_{3}'.format(TEST_COURSE_ORG.lower(),
+                                                              TEST_COURSE_NUMBER.replace('.', '_'),
+                                                              problem_url_name, response_id)
+
+        # make sure that the requested user is logged in, so that the ajax call works
+        # on the right problem:
+        if self.current_user != username:
+            self.login_username(username)
+        # make ajax call:
+        modx_url = reverse('modx_dispatch',
+                            kwargs={
+                                'course_id': self.course.id,
+                                'location': TestRegrading.problem_location(problem_url_name),
+                                'dispatch': 'problem_check', })
+
+        resp = self.client.post(modx_url, {
+            get_input_id('2_1'): responses[0],
+            get_input_id('3_1'): responses[1],
+        })
+        return resp
+
+    def _create_task_request(self, requester_username):
+        """Generate request that can be used for submitting tasks"""
+        request = Mock()
+        request.user = User.objects.get(username=requester_username)
+        request.get_host = Mock(return_value="testhost")
+        request.META = {'REMOTE_ADDR': '0:0:0:0', 'SERVER_NAME': 'testhost'}
+        request.is_secure = Mock(return_value=False)
+        return request
+
+    def regrade_all_student_answers(self, instructor, problem_url_name):
+        """Submits the current problem for regrading"""
+        return submit_regrade_problem_for_all_students(self._create_task_request(instructor), self.course.id,
+                                                       TestRegradingBase.problem_location(problem_url_name))
+
+    def regrade_one_student_answer(self, instructor, problem_url_name, student):
+        """Submits the current problem for regrading for a particular student"""
+        return submit_regrade_problem_for_student(self._create_task_request(instructor), self.course.id,
+                                                  TestRegradingBase.problem_location(problem_url_name),
+                                                  student)
+
+    def show_correct_answer(self, problem_url_name):
+        modx_url = reverse('modx_dispatch',
+                            kwargs={
+                                'course_id': self.course.id,
+                                'location': TestRegradingBase.problem_location(problem_url_name),
+                                'dispatch': 'problem_show', })
+        return self.client.post(modx_url, {})
+
+    def get_student_module(self, username, descriptor):
+        return StudentModule.objects.get(course_id=self.course.id,
+                                         student=User.objects.get(username=username),
+                                         module_type=descriptor.location.category,
+                                         module_state_key=descriptor.location.url(),
+                                         )
+
+    def check_state(self, username, descriptor, expected_score, expected_max_score, expected_attempts):
+        module = self.get_student_module(username, descriptor)
+        self.assertEqual(module.grade, expected_score, "Scores were not equal")
+        self.assertEqual(module.max_grade, expected_max_score, "Max scores were not equal")
+        state = json.loads(module.state)
+        attempts = state['attempts']
+        self.assertEqual(attempts, expected_attempts, "Attempts were not equal")
+        if attempts > 0:
+            self.assertTrue('correct_map' in state)
+            self.assertTrue('student_answers' in state)
+            self.assertGreater(len(state['correct_map']), 0)
+            self.assertGreater(len(state['student_answers']), 0)
+
+
+class TestRegrading(TestRegradingBase):
+
+    def setUp(self):
+        self.initialize_course()
+        self.create_instructor('instructor')
+        self.create_student('u1')
+        self.create_student('u2')
+        self.create_student('u3')
+        self.create_student('u4')
+        self.logout()
+
+    def testRegradingOptionProblem(self):
+        '''Run regrade scenario on option problem'''
+        # get descriptor:
+        problem_url_name = 'H1P1'
+        self.define_option_problem(problem_url_name)
+        location = TestRegrading.problem_location(problem_url_name)
+        descriptor = self.module_store.get_instance(self.course.id, location)
+
+        # first store answers for each of the separate users:
+        self.submit_student_answer('u1', problem_url_name, ['Option 1', 'Option 1'])
+        self.submit_student_answer('u2', problem_url_name, ['Option 1', 'Option 2'])
+        self.submit_student_answer('u3', problem_url_name, ['Option 2', 'Option 1'])
+        self.submit_student_answer('u4', problem_url_name, ['Option 2', 'Option 2'])
+
+        self.check_state('u1', descriptor, 2, 2, 1)
+        self.check_state('u2', descriptor, 1, 2, 1)
+        self.check_state('u3', descriptor, 1, 2, 1)
+        self.check_state('u4', descriptor, 0, 2, 1)
+
+        # update the data in the problem definition
+        self.redefine_option_problem(problem_url_name)
+        # confirm that simply rendering the problem again does not result in a change
+        # in the grade:
+        self.render_problem('u1', problem_url_name)
+        self.check_state('u1', descriptor, 2, 2, 1)
+
+        # regrade the problem for only one student -- only that student's grade should change:
+        self.regrade_one_student_answer('instructor', problem_url_name, User.objects.get(username='u1'))
+        self.check_state('u1', descriptor, 0, 2, 1)
+        self.check_state('u2', descriptor, 1, 2, 1)
+        self.check_state('u3', descriptor, 1, 2, 1)
+        self.check_state('u4', descriptor, 0, 2, 1)
+
+        # regrade the problem for all students
+        self.regrade_all_student_answers('instructor', problem_url_name)
+        self.check_state('u1', descriptor, 0, 2, 1)
+        self.check_state('u2', descriptor, 1, 2, 1)
+        self.check_state('u3', descriptor, 1, 2, 1)
+        self.check_state('u4', descriptor, 2, 2, 1)
+
+    def define_code_response_problem(self, problem_url_name):
+        factory = CodeResponseXMLFactory()
+        grader_payload = json.dumps({"grader": "ps04/grade_square.py"})
+        problem_xml = factory.build_xml(initial_display="def square(x):",
+                                        answer_display="answer",
+                                        grader_payload=grader_payload,
+                                        num_responses=2)
+        ItemFactory.create(parent_location=self.problem_section.location,
+                           template="i4x://edx/templates/problem/Blank_Common_Problem",
+                           display_name=str(problem_url_name),
+                           data=problem_xml)
+
+    def testRegradingFailure(self):
+        """Simulate a failure in regrading a problem"""
+        problem_url_name = 'H1P1'
+        self.define_option_problem(problem_url_name)
+        self.submit_student_answer('u1', problem_url_name, ['Option 1', 'Option 1'])
+
+        expected_message = "bad things happened"
+        with patch('capa.capa_problem.LoncapaProblem.regrade_existing_answers') as mock_regrade:
+            mock_regrade.side_effect = ZeroDivisionError(expected_message)
+            course_task_log = self.regrade_all_student_answers('instructor', problem_url_name)
+
+        # check task_log returned
+        self.assertEqual(course_task_log.task_state, 'FAILURE')
+        self.assertEqual(course_task_log.student, None)
+        self.assertEqual(course_task_log.requester.username, 'instructor')
+        self.assertEqual(course_task_log.task_name, 'regrade_problem')
+        self.assertEqual(course_task_log.task_args, TestRegrading.problem_location(problem_url_name))
+        status = json.loads(course_task_log.task_progress)
+        self.assertEqual(status['exception'], 'ZeroDivisionError')
+        self.assertEqual(status['message'], expected_message)
+
+        # check status returned:
+        mock_request = Mock()
+        response = course_task_log_status(mock_request, task_id=course_task_log.task_id)
+        status = json.loads(response.content)
+        self.assertEqual(status['message'], expected_message)
+
+    def testRegradingNonProblem(self):
+        """confirm that a non-problem will not submit"""
+        problem_url_name = self.problem_section.location.url()
+        with self.assertRaises(NotImplementedError):
+            self.regrade_all_student_answers('instructor', problem_url_name)
+
+    def testRegradingNonexistentProblem(self):
+        """confirm that a non-existent problem will not submit"""
+        problem_url_name = 'NonexistentProblem'
+        with self.assertRaises(ItemNotFoundError):
+            self.regrade_all_student_answers('instructor', problem_url_name)
+
+    def testRegradingCodeProblem(self):
+        '''Run regrade scenario on problem with code submission'''
+        problem_url_name = 'H1P2'
+        self.define_code_response_problem(problem_url_name)
+        # we fully create the CodeResponse problem, but just pretend that we're queuing it:
+        with patch('capa.xqueue_interface.XQueueInterface.send_to_queue') as mock_send_to_queue:
+            mock_send_to_queue.return_value = (0, "Successfully queued")
+            self.submit_student_answer('u1', problem_url_name, ["answer1", "answer2"])
+
+        course_task_log = self.regrade_all_student_answers('instructor', problem_url_name)
+        self.assertEqual(course_task_log.task_state, 'FAILURE')
+        status = json.loads(course_task_log.task_progress)
+        self.assertEqual(status['exception'], 'NotImplementedError')
+        self.assertEqual(status['message'], "Problem's definition does not support regrading")
+
+        mock_request = Mock()
+        response = course_task_log_status(mock_request, task_id=course_task_log.task_id)
+        status = json.loads(response.content)
+        self.assertEqual(status['message'], "Problem's definition does not support regrading")