From f10df353d2fa68d84da725b9b855aac02bcc88be Mon Sep 17 00:00:00 2001
From: David Ormsbee <dave@edx.org>
Date: Mon, 2 Dec 2013 16:07:56 -0500
Subject: [PATCH] Add basic tests of gradeset iteration.

---
 .../courseware/tests/test_grades.py           | 122 ++++++++++++++++++
 1 file changed, 122 insertions(+)
 create mode 100644 lms/djangoapps/courseware/tests/test_grades.py

diff --git a/lms/djangoapps/courseware/tests/test_grades.py b/lms/djangoapps/courseware/tests/test_grades.py
new file mode 100644
index 0000000000..5ee6953161
--- /dev/null
+++ b/lms/djangoapps/courseware/tests/test_grades.py
@@ -0,0 +1,122 @@
+"""
+Test grade calculation.
+"""
+from django.http import Http404
+from django.test.utils import override_settings
+from mock import patch
+
+from courseware.tests.modulestore_config import TEST_DATA_MIXED_MODULESTORE
+from student.tests.factories import UserFactory
+from xmodule.modulestore.tests.factories import CourseFactory
+from xmodule.modulestore.tests.django_utils import ModuleStoreTestCase
+
+from courseware.grades import grade, iterate_grades_for
+
+
+def _grade_with_errors(student, request, course, keep_raw_scores=False):
+    """This fake grade method will throw exceptions for student3 and
+    student4, but allow any other students to go through normal grading.
+
+    It's meant to simulate when something goes really wrong while trying to
+    grade a particular student, so we can test that we won't kill the entire
+    course grading run.
+    """
+    if student.username in ['student3', 'student4']:
+        raise Exception("I don't like {}".format(student.username))
+
+    return grade(student, request, course, keep_raw_scores=keep_raw_scores)
+
+
+@override_settings(MODULESTORE=TEST_DATA_MIXED_MODULESTORE)
+class TestGradeIteration(ModuleStoreTestCase):
+    """
+    Test iteration through student gradesets.
+    """
+    COURSE_NUM = "1000"
+    COURSE_NAME = "grading_test_course"
+
+    def setUp(self):
+        """
+        Create a course and a handful of users to assign grades
+        """
+        self.course = CourseFactory.create(
+            display_name=self.COURSE_NAME,
+            number=self.COURSE_NUM
+        )
+        self.students = [
+            UserFactory.create(username='student1'),
+            UserFactory.create(username='student2'),
+            UserFactory.create(username='student3'),
+            UserFactory.create(username='student4'),
+            UserFactory.create(username='student5'),
+        ]
+
+    def test_empty_student_list(self):
+        """If we don't pass in any students, it should return a zero-length
+        iterator, but it shouldn't error."""
+        gradeset_results = list(iterate_grades_for(self.course.id, []))
+        self.assertEqual(gradeset_results, [])
+
+    def test_nonexistent_course(self):
+        """If the course we want to get grades for does not exist, a `Http404`
+        should be raised. This is a horrible crossing of abstraction boundaries
+        and should be fixed, but for now we're just testing the behavior. :-("""
+        with self.assertRaises(Http404):
+            gradeset_results = iterate_grades_for("I/dont/exist", [])
+            gradeset_results.next()
+
+    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)
+        self.assertEqual(len(all_errors), 0)
+        for gradeset in all_gradesets.values():
+            self.assertIsNone(gradeset['grade'])
+            self.assertEqual(gradeset['percent'], 0.0)
+
+    @patch('courseware.grades.grade', _grade_with_errors)
+    def test_grading_exception(self):
+        """Test that we correctly capture exception messages that bubble up from
+        grading. Note that we only see errors at this level if the grading
+        process for this student fails entirely due to an unexpected event --
+        having errors in the problem sets will not trigger this.
+
+        We patch the grade() method with our own, which will generate the errors
+        for student3 and student4.
+        """
+        all_gradesets, all_errors = self._gradesets_and_errors_for(self.course.id, self.students)
+        student1, student2, student3, student4, student5 = self.students
+        self.assertEqual(
+            all_errors,
+            {
+                student3: "I don't like student3",
+                student4: "I don't like student4"
+            }
+        )
+
+        # But we should still have five gradesets
+        self.assertEqual(len(all_gradesets), 5)
+
+        # Even though two will simply be empty
+        self.assertFalse(all_gradesets[student3])
+        self.assertFalse(all_gradesets[student4])
+
+        # The rest will have grade information in them
+        self.assertTrue(all_gradesets[student1])
+        self.assertTrue(all_gradesets[student2])
+        self.assertTrue(all_gradesets[student5])
+
+    ################################# Helpers #################################
+    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
+        their respective error messages."""
+        students_to_gradesets = {}
+        students_to_errors = {}
+
+        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
+
+        return students_to_gradesets, students_to_errors