Refactor and add tests for new grade report.

* Handle grading errors

lms/djangoapps/courseware/grades.py

@@ -229,7 +229,13 @@ def _grade(student, request, course, keep_raw_scores):
                         graded = False
 
                     scores.append(
-                        Score(correct, total, graded, module_descriptor.display_name_with_default, module_descriptor.location)
+                        Score(
+                            correct,
+                            total,
+                            graded,
+                            module_descriptor.display_name_with_default,
+                            module_descriptor.location
+                        )
                     )
 
                 _, graded_total = graders.aggregate_scores(scores, section_name)

lms/djangoapps/courseware/tests/test_grades.py

@@ -68,7 +68,7 @@ class TestGradeIteration(ModuleStoreTestCase):
 
     def test_all_empty_grades(self):
         """No students have grade entries"""
-        all_gradesets, all_errors = self._gradesets_and_errors_for(self.course.id, self.students, keep_raw_scores=True)
+        all_gradesets, all_errors = self._gradesets_and_errors_for(self.course.id, self.students)
         self.assertEqual(len(all_errors), 0)
         for gradeset in all_gradesets.values():
             self.assertIsNone(gradeset['grade'])
@@ -107,7 +107,7 @@ class TestGradeIteration(ModuleStoreTestCase):
         self.assertTrue(all_gradesets[student5])
 
     ################################# Helpers #################################
-    def _gradesets_and_errors_for(self, course_id, students, keep_raw_scores=False):
+    def _gradesets_and_errors_for(self, course_id, students):
         """Simple helper method to iterate through student grades and give us
         two dictionaries -- one that has all students and their respective
         gradesets, and one that has only students that could not be graded and
@@ -115,7 +115,7 @@ class TestGradeIteration(ModuleStoreTestCase):
         students_to_gradesets = {}
         students_to_errors = {}
 
-        for student, gradeset, err_msg in iterate_grades_for(course_id, students, keep_raw_scores):
+        for student, gradeset, err_msg in iterate_grades_for(course_id, students):
             students_to_gradesets[student] = gradeset
             if err_msg:
                 students_to_errors[student] = err_msg