[LTI Provider] Grade passback for non-leaf blocks.

This change allows graded assignments to be added to a campus LMS
regardless of the granularity at which the problem sits. Previously
a grade could only be returned if the usage ID for the problem itself
was specified in the LTI launch.

The code assumes that courses taking advantage of this functionality
are arranged in a hiearchy (with sections being parents to verticals,
and verticals being parents to problems). When a grading event occurs
it traverses the parent hiearchy to identify any previous graded LTI
launches for which the new scoring event should generate a grade
update. It then calculates and sends scores to each of those outcome
services.

Since grade calculation is an expensive operation, the code optimizes
the case where a problem has been added only once as a leaf unit. In
that case it is able to behave as before, just taking the grade from
the signal without having to calculate grades for the whole course.

lms/djangoapps/courseware/grades.py

@@ -122,6 +122,51 @@ def get(self, location):
         return max_score
 
 
+class ProgressSummary(object):
+    """
+    Wrapper class for the computation of a user's scores across a course.
+
+    Attributes
+       chapters: a summary of all sections with problems in the course. It is
+       organized as an array of chapters, each containing an array of sections,
+       each containing an array of scores. This contains information for graded
+       and ungraded problems, and is good for displaying a course summary with
+       due dates, etc.
+
+       weighted_scores: a dictionary mapping module locations to weighted Score
+       objects.
+
+       locations_to_children: a dictionary mapping module locations to their
+       direct descendants.
+    """
+    def __init__(self, chapters, weighted_scores, locations_to_children):
+        self.chapters = chapters
+        self.weighted_scores = weighted_scores
+        self.locations_to_children = locations_to_children
+
+    def score_for_module(self, location):
+        """
+        Calculate the aggregate weighted score for any location in the course.
+        This method returns a tuple containing (earned_score, possible_score).
+
+        If the location is of 'problem' type, this method will return the
+        possible and earned scores for that problem. If the location refers to a
+        composite module (a vertical or section ) the scores will be the sums of
+        all scored problems that are children of the chosen location.
+        """
+        if location in self.weighted_scores:
+            score = self.weighted_scores[location]
+            return score.earned, score.possible
+        children = self.locations_to_children[location]
+        earned = 0.0
+        possible = 0.0
+        for child in children:
+            child_earned, child_possible = self.score_for_module(child)
+            earned += child_earned
+            possible += child_possible
+        return earned, possible
+
+
 def descriptor_affects_grading(block_types_affecting_grading, descriptor):
     """
     Returns True if the descriptor could have any impact on grading, else False.
@@ -452,6 +497,21 @@ def progress_summary(student, request, course, field_data_cache=None, scores_cli
     in case there are unanticipated errors.
     """
     with manual_transaction():
+        progress = _progress_summary(student, request, course, field_data_cache, scores_client)
+        if progress:
+            return progress.chapters
+        else:
+            return None
+
+
+@transaction.commit_manually
+def get_weighted_scores(student, course, field_data_cache=None, scores_client=None):
+    """
+    Uses the _progress_summary method to return a ProgressSummmary object
+    containing details of a students weighted scores for the course.
+    """
+    with manual_transaction():
+        request = _get_mock_request(student)
         return _progress_summary(student, request, course, field_data_cache, scores_client)
 
 
@@ -502,14 +562,15 @@ def _progress_summary(student, request, course, field_data_cache=None, scores_cl
     max_scores_cache.fetch_from_remote(field_data_cache.scorable_locations)
 
     chapters = []
+    locations_to_children = defaultdict(list)
+    locations_to_weighted_scores = {}
     # Don't include chapters that aren't displayable (e.g. due to error)
     for chapter_module in course_module.get_display_items():
         # Skip if the chapter is hidden
         if chapter_module.hide_from_toc:
             continue
 
         sections = []
-
         for section_module in chapter_module.get_display_items():
             # Skip if the section is hidden
             with manual_transaction():
@@ -524,7 +585,7 @@ def _progress_summary(student, request, course, field_data_cache=None, scores_cl
                 for module_descriptor in yield_dynamic_descriptor_descendants(
                         section_module, student.id, module_creator
                 ):
-                    course_id = course.id
+                    locations_to_children[module_descriptor.parent].append(module_descriptor.location)
                     (correct, total) = get_score(
                         student,
                         module_descriptor,
@@ -536,16 +597,17 @@ def _progress_summary(student, request, course, field_data_cache=None, scores_cl
                     if correct is None and total is None:
                         continue
 
-                    scores.append(
-                        Score(
-                            correct,
-                            total,
-                            graded,
-                            module_descriptor.display_name_with_default,
-                            module_descriptor.location
-                        )
+                    weighted_location_score = Score(
+                        correct,
+                        total,
+                        graded,
+                        module_descriptor.display_name_with_default,
+                        module_descriptor.location
                     )
 
+                    scores.append(weighted_location_score)
+                    locations_to_weighted_scores[module_descriptor.location] = weighted_location_score
+
                 scores.reverse()
                 section_total, _ = graders.aggregate_scores(
                     scores, section_module.display_name_with_default)
@@ -570,7 +632,7 @@ def _progress_summary(student, request, course, field_data_cache=None, scores_cl
 
     max_scores_cache.push_to_remote()
 
-    return chapters
+    return ProgressSummary(chapters, locations_to_weighted_scores, locations_to_children)
 
 
 def weighted_score(raw_correct, raw_total, weight):
@@ -698,15 +760,10 @@ def iterate_grades_for(course_or_id, students, keep_raw_scores=False):
     else:
         course = course_or_id
 
-    # We make a fake request because grading code expects to be able to look at
-    # the request. We have to attach the correct user to the request before
-    # grading that student.
-    request = RequestFactory().get('/')
-
     for student in students:
         with dog_stats_api.timer('lms.grades.iterate_grades_for', tags=[u'action:{}'.format(course.id)]):
             try:
-                request.user = student
+                request = _get_mock_request(student)
                 # Grading calls problem rendering, which calls masquerading,
                 # which checks session vars -- thus the empty session dict below.
                 # It's not pretty, but untangling that is currently beyond the
@@ -725,3 +782,14 @@ def iterate_grades_for(course_or_id, students, keep_raw_scores=False):
                     exc.message
                 )
                 yield student, {}, exc.message
+
+
+def _get_mock_request(student):
+    """
+    Make a fake request because grading code expects to be able to look at
+    the request. We have to attach the correct user to the request before
+    grading that student.
+    """
+    request = RequestFactory().get('/')
+    request.user = student
+    return request

lms/djangoapps/courseware/tests/test_grades.py

@@ -2,13 +2,15 @@
 Test grade calculation.
 """
 from django.http import Http404
+from django.test import TestCase
 from django.test.client import RequestFactory
 
-from mock import patch
+from mock import patch, MagicMock
 from nose.plugins.attrib import attr
 from opaque_keys.edx.locations import SlashSeparatedCourseKey
+from opaque_keys.edx.locator import CourseLocator, BlockUsageLocator
 
-from courseware.grades import field_data_cache_for_grading, grade, iterate_grades_for, MaxScoresCache
+from courseware.grades import field_data_cache_for_grading, grade, iterate_grades_for, MaxScoresCache, ProgressSummary
 from student.tests.factories import UserFactory
 from student.models import CourseEnrollment
 from xmodule.modulestore.tests.factories import CourseFactory, ItemFactory
@@ -194,3 +196,125 @@ def test_field_data_cache_scorable_locations(self):
         self.assertNotIn('html', block_types)
         self.assertNotIn('discussion', block_types)
         self.assertIn('problem', block_types)
+
+
+class TestProgressSummary(TestCase):
+    """
+    Test the method that calculates the score for a given block based on the
+    cumulative scores of its children. This test class uses a hard-coded block
+    hierarchy with scores as follows:
+                                                a
+                                       +--------+--------+
+                                       b                 c
+                        +--------------+-----------+     |
+                        d              e           f     g
+                     +-----+     +-----+-----+     |     |
+                     h     i     j     k     l     m     n
+                   (2/5) (3/5) (0/1)   -   (1/3)   -   (3/10)
+
+    """
+    def setUp(self):
+        super(TestProgressSummary, self).setUp()
+        self.course_key = CourseLocator(
+            org='some_org',
+            course='some_course',
+            run='some_run'
+        )
+        self.loc_a = self.create_location('chapter', 'a')
+        self.loc_b = self.create_location('section', 'b')
+        self.loc_c = self.create_location('section', 'c')
+        self.loc_d = self.create_location('vertical', 'd')
+        self.loc_e = self.create_location('vertical', 'e')
+        self.loc_f = self.create_location('vertical', 'f')
+        self.loc_g = self.create_location('vertical', 'g')
+        self.loc_h = self.create_location('problem', 'h')
+        self.loc_i = self.create_location('problem', 'i')
+        self.loc_j = self.create_location('problem', 'j')
+        self.loc_k = self.create_location('html', 'k')
+        self.loc_l = self.create_location('problem', 'l')
+        self.loc_m = self.create_location('html', 'm')
+        self.loc_n = self.create_location('problem', 'n')
+
+        weighted_scores = {
+            self.loc_h: self.create_score(2, 5),
+            self.loc_i: self.create_score(3, 5),
+            self.loc_j: self.create_score(0, 1),
+            self.loc_l: self.create_score(1, 3),
+            self.loc_n: self.create_score(3, 10),
+        }
+        locations_to_scored_children = {
+            self.loc_a: [self.loc_h, self.loc_i, self.loc_j, self.loc_l, self.loc_n],
+            self.loc_b: [self.loc_h, self.loc_i, self.loc_j, self.loc_l],
+            self.loc_c: [self.loc_n],
+            self.loc_d: [self.loc_h, self.loc_i],
+            self.loc_e: [self.loc_j, self.loc_l],
+            self.loc_f: [],
+            self.loc_g: [self.loc_n],
+            self.loc_k: [],
+            self.loc_m: [],
+        }
+        self.progress_summary = ProgressSummary(
+            None, weighted_scores, locations_to_scored_children
+        )
+
+    def create_score(self, earned, possible):
+        """
+        Create a new mock Score object with specified earned and possible values
+        """
+        score = MagicMock()
+        score.possible = possible
+        score.earned = earned
+        return score
+
+    def create_location(self, block_type, block_id):
+        """
+        Create a new BlockUsageLocation with the given type and ID.
+        """
+        return BlockUsageLocator(
+            course_key=self.course_key, block_type=block_type, block_id=block_id
+        )
+
+    def test_score_chapter(self):
+        earned, possible = self.progress_summary.score_for_module(self.loc_a)
+        self.assertEqual(earned, 9)
+        self.assertEqual(possible, 24)
+
+    def test_score_section_many_leaves(self):
+        earned, possible = self.progress_summary.score_for_module(self.loc_b)
+        self.assertEqual(earned, 6)
+        self.assertEqual(possible, 14)
+
+    def test_score_section_one_leaf(self):
+        earned, possible = self.progress_summary.score_for_module(self.loc_c)
+        self.assertEqual(earned, 3)
+        self.assertEqual(possible, 10)
+
+    def test_score_vertical_two_leaves(self):
+        earned, possible = self.progress_summary.score_for_module(self.loc_d)
+        self.assertEqual(earned, 5)
+        self.assertEqual(possible, 10)
+
+    def test_score_vertical_two_leaves_one_unscored(self):
+        earned, possible = self.progress_summary.score_for_module(self.loc_e)
+        self.assertEqual(earned, 1)
+        self.assertEqual(possible, 4)
+
+    def test_score_vertical_no_score(self):
+        earned, possible = self.progress_summary.score_for_module(self.loc_f)
+        self.assertEqual(earned, 0)
+        self.assertEqual(possible, 0)
+
+    def test_score_vertical_one_leaf(self):
+        earned, possible = self.progress_summary.score_for_module(self.loc_g)
+        self.assertEqual(earned, 3)
+        self.assertEqual(possible, 10)
+
+    def test_score_leaf(self):
+        earned, possible = self.progress_summary.score_for_module(self.loc_h)
+        self.assertEqual(earned, 2)
+        self.assertEqual(possible, 5)
+
+    def test_score_leaf_no_score(self):
+        earned, possible = self.progress_summary.score_for_module(self.loc_m)
+        self.assertEqual(earned, 0)
+        self.assertEqual(possible, 0)

lms/djangoapps/courseware/tests/test_submitting_problems.py

@@ -136,6 +136,36 @@ def show_question_answer(self, problem_url_name):
         resp = self.client.post(modx_url)
         return resp
 
+
+class TestSubmittingProblems(ModuleStoreTestCase, LoginEnrollmentTestCase, ProblemSubmissionTestMixin):
+    """
+    Check that a course gets graded properly.
+    """
+
+    # arbitrary constant
+    COURSE_SLUG = "100"
+    COURSE_NAME = "test_course"
+
+    def setUp(self):
+
+        super(TestSubmittingProblems, self).setUp(create_user=False)
+        # Create course
+        self.course = CourseFactory.create(display_name=self.COURSE_NAME, number=self.COURSE_SLUG)
+        assert self.course, "Couldn't load course %r" % self.COURSE_NAME
+
+        # create a test student
+        self.student = 'view@test.com'
+        self.password = 'foo'
+        self.create_account('u1', self.student, self.password)
+        self.activate_user(self.student)
+        self.enroll(self.course)
+        self.student_user = User.objects.get(email=self.student)
+        self.factory = RequestFactory()
+        # Disable the score change signal to prevent other components from being pulled into tests.
+        signal_patch = patch('courseware.module_render.SCORE_CHANGED.send')
+        signal_patch.start()
+        self.addCleanup(signal_patch.stop)
+
     def add_dropdown_to_section(self, section_location, name, num_inputs=2):
         """
         Create and return a dropdown problem.

lms/djangoapps/instructor/tests/test_enrollment.py

@@ -393,7 +393,10 @@ def test_delete_student_attempts(self):
                 module_state_key=msk
             ).count(), 0)
 
-    def test_delete_submission_scores(self):
+    # Disable the score change signal to prevent other components from being
+    # pulled into tests.
+    @mock.patch('courseware.module_render.SCORE_CHANGED.send')
+    def test_delete_submission_scores(self, _lti_mock):
         user = UserFactory()
         problem_location = self.course_key.make_usage_key('dummy', 'module')