diff --git a/lms/djangoapps/grades/tests/base.py b/lms/djangoapps/grades/tests/base.py
index 969c61b7af..bf476a9cb4 100644
--- a/lms/djangoapps/grades/tests/base.py
+++ b/lms/djangoapps/grades/tests/base.py
@@ -1,6 +1,8 @@
 """
 Base file for Grades tests
 """
+from __future__ import absolute_import
+
 from crum import set_current_request
 
 from capa.tests.response_xml_factory import MultipleChoiceResponseXMLFactory
diff --git a/lms/djangoapps/grades/tests/integration/test_access.py b/lms/djangoapps/grades/tests/integration/test_access.py
index a7846df75d..923705507f 100644
--- a/lms/djangoapps/grades/tests/integration/test_access.py
+++ b/lms/djangoapps/grades/tests/integration/test_access.py
@@ -1,6 +1,8 @@
 """
 Test grading with access changes.
 """
+from __future__ import absolute_import
+
 from crum import set_current_request
 
 from capa.tests.response_xml_factory import MultipleChoiceResponseXMLFactory
diff --git a/lms/djangoapps/grades/tests/integration/test_events.py b/lms/djangoapps/grades/tests/integration/test_events.py
index f9da063901..829e37a9fa 100644
--- a/lms/djangoapps/grades/tests/integration/test_events.py
+++ b/lms/djangoapps/grades/tests/integration/test_events.py
@@ -2,8 +2,12 @@
 Test grading events across apps.
 """
 
-from mock import call as mock_call, patch
+from __future__ import absolute_import
+
+import six
 from crum import set_current_request
+from mock import call as mock_call
+from mock import patch
 
 from capa.tests.response_xml_factory import MultipleChoiceResponseXMLFactory
 from courseware.tests.test_submitting_problems import ProblemSubmissionTestMixin
@@ -85,11 +89,11 @@ class GradesEventIntegrationTest(ProblemSubmissionTestMixin, SharedModuleStoreTe
                 mock_call(
                     events.PROBLEM_SUBMITTED_EVENT_TYPE,
                     {
-                        'user_id': unicode(self.student.id),
+                        'user_id': six.text_type(self.student.id),
                         'event_transaction_id': event_transaction_id,
                         'event_transaction_type': events.PROBLEM_SUBMITTED_EVENT_TYPE,
-                        'course_id': unicode(self.course.id),
-                        'problem_id': unicode(self.problem.location),
+                        'course_id': six.text_type(self.course.id),
+                        'problem_id': six.text_type(self.problem.location),
                         'weighted_earned': 2.0,
                         'weighted_possible': 2.0,
                     },
@@ -97,15 +101,15 @@ class GradesEventIntegrationTest(ProblemSubmissionTestMixin, SharedModuleStoreTe
                 mock_call(
                     events.COURSE_GRADE_CALCULATED,
                     {
-                        'course_version': unicode(course.course_version),
+                        'course_version': six.text_type(course.course_version),
                         'percent_grade': 0.02,
                         'grading_policy_hash': u'ChVp0lHGQGCevD0t4njna/C44zQ=',
-                        'user_id': unicode(self.student.id),
+                        'user_id': six.text_type(self.student.id),
                         'letter_grade': u'',
                         'event_transaction_id': event_transaction_id,
                         'event_transaction_type': events.PROBLEM_SUBMITTED_EVENT_TYPE,
-                        'course_id': unicode(self.course.id),
-                        'course_edited_timestamp': unicode(course.subtree_edited_on),
+                        'course_id': six.text_type(self.course.id),
+                        'course_edited_timestamp': six.text_type(course.subtree_edited_on),
                     }
                 ),
             ],
@@ -126,10 +130,10 @@ class GradesEventIntegrationTest(ProblemSubmissionTestMixin, SharedModuleStoreTe
         enrollment_tracker.emit.assert_called_with(
             events.STATE_DELETED_EVENT_TYPE,
             {
-                'user_id': unicode(self.student.id),
-                'course_id': unicode(self.course.id),
-                'problem_id': unicode(self.problem.location),
-                'instructor_id': unicode(self.instructor.id),
+                'user_id': six.text_type(self.student.id),
+                'course_id': six.text_type(self.course.id),
+                'problem_id': six.text_type(self.problem.location),
+                'instructor_id': six.text_type(self.instructor.id),
                 'event_transaction_id': event_transaction_id,
                 'event_transaction_type': events.STATE_DELETED_EVENT_TYPE,
             }
@@ -140,13 +144,13 @@ class GradesEventIntegrationTest(ProblemSubmissionTestMixin, SharedModuleStoreTe
             {
                 'percent_grade': 0.0,
                 'grading_policy_hash': u'ChVp0lHGQGCevD0t4njna/C44zQ=',
-                'user_id': unicode(self.student.id),
+                'user_id': six.text_type(self.student.id),
                 'letter_grade': u'',
                 'event_transaction_id': event_transaction_id,
                 'event_transaction_type': events.STATE_DELETED_EVENT_TYPE,
-                'course_id': unicode(self.course.id),
-                'course_edited_timestamp': unicode(course.subtree_edited_on),
-                'course_version': unicode(course.course_version),
+                'course_id': six.text_type(self.course.id),
+                'course_edited_timestamp': six.text_type(course.subtree_edited_on),
+                'course_version': six.text_type(course.course_version),
             }
         )
 
@@ -175,7 +179,7 @@ class GradesEventIntegrationTest(ProblemSubmissionTestMixin, SharedModuleStoreTe
         for args in events_tracker.get_tracker().context.call_args_list:
             self.assertEqual(
                 args[0][1],
-                {'course_id': unicode(self.course.id), 'org_id': unicode(self.course.org)}
+                {'course_id': six.text_type(self.course.id), 'org_id': six.text_type(self.course.org)}
             )
 
         event_transaction_id = events_tracker.emit.mock_calls[0][1][1]['event_transaction_id']
@@ -184,13 +188,13 @@ class GradesEventIntegrationTest(ProblemSubmissionTestMixin, SharedModuleStoreTe
                 mock_call(
                     events.GRADES_RESCORE_EVENT_TYPE,
                     {
-                        'course_id': unicode(self.course.id),
-                        'user_id': unicode(self.student.id),
-                        'problem_id': unicode(self.problem.location),
+                        'course_id': six.text_type(self.course.id),
+                        'user_id': six.text_type(self.student.id),
+                        'problem_id': six.text_type(self.problem.location),
                         'new_weighted_earned': 2,
                         'new_weighted_possible': 2,
                         'only_if_higher': False,
-                        'instructor_id': unicode(self.instructor.id),
+                        'instructor_id': six.text_type(self.instructor.id),
                         'event_transaction_id': event_transaction_id,
                         'event_transaction_type': events.GRADES_RESCORE_EVENT_TYPE,
                     },
@@ -198,15 +202,15 @@ class GradesEventIntegrationTest(ProblemSubmissionTestMixin, SharedModuleStoreTe
                 mock_call(
                     events.COURSE_GRADE_CALCULATED,
                     {
-                        'course_version': unicode(course.course_version),
+                        'course_version': six.text_type(course.course_version),
                         'percent_grade': 0.02,
                         'grading_policy_hash': u'ChVp0lHGQGCevD0t4njna/C44zQ=',
-                        'user_id': unicode(self.student.id),
+                        'user_id': six.text_type(self.student.id),
                         'letter_grade': u'',
                         'event_transaction_id': event_transaction_id,
                         'event_transaction_type': events.GRADES_RESCORE_EVENT_TYPE,
-                        'course_id': unicode(self.course.id),
-                        'course_edited_timestamp': unicode(course.subtree_edited_on),
+                        'course_id': six.text_type(self.course.id),
+                        'course_edited_timestamp': six.text_type(course.subtree_edited_on),
                     },
                 ),
             ],
diff --git a/lms/djangoapps/grades/tests/integration/test_problems.py b/lms/djangoapps/grades/tests/integration/test_problems.py
index 3c249f4abe..c52afb99c4 100644
--- a/lms/djangoapps/grades/tests/integration/test_problems.py
+++ b/lms/djangoapps/grades/tests/integration/test_problems.py
@@ -1,9 +1,14 @@
+# pylint: disable=missing-docstring
+from __future__ import absolute_import
+
 import datetime
 import itertools
 
 import ddt
 import pytz
 from crum import set_current_request
+from six.moves import range
+
 from capa.tests.response_xml_factory import MultipleChoiceResponseXMLFactory
 from courseware.tests.test_submitting_problems import ProblemSubmissionTestMixin
 from lms.djangoapps.course_blocks.api import get_course_blocks
diff --git a/lms/djangoapps/grades/tests/test_course_data.py b/lms/djangoapps/grades/tests/test_course_data.py
index d9a4d35006..372be7aa3d 100644
--- a/lms/djangoapps/grades/tests/test_course_data.py
+++ b/lms/djangoapps/grades/tests/test_course_data.py
@@ -1,8 +1,12 @@
 """
 Tests for CourseData utility class.
 """
-from lms.djangoapps.course_blocks.api import get_course_blocks
+from __future__ import absolute_import
+
+import six
 from mock import patch
+
+from lms.djangoapps.course_blocks.api import get_course_blocks
 from openedx.core.djangoapps.content.block_structure.api import get_course_in_cache
 from student.tests.factories import UserFactory
 from xmodule.modulestore import ModuleStoreEnum
@@ -73,7 +77,7 @@ class CourseDataTest(ModuleStoreTestCase):
             self.assertEquals(course_data.course.id, self.course.id)
             self.assertEquals(course_data.version, self.course.course_version)
             self.assertEquals(course_data.edited_on, expected_edited_on)
-            self.assertIn(u'Course: course_key', unicode(course_data))
+            self.assertIn(u'Course: course_key', six.text_type(course_data))
             self.assertIn(u'Course: course_key', course_data.full_string())
 
     def test_no_data(self):
diff --git a/lms/djangoapps/grades/tests/test_course_grade.py b/lms/djangoapps/grades/tests/test_course_grade.py
index d546706620..534cb6bdd4 100644
--- a/lms/djangoapps/grades/tests/test_course_grade.py
+++ b/lms/djangoapps/grades/tests/test_course_grade.py
@@ -1,7 +1,11 @@
+# pylint: disable=missing-docstring
+from __future__ import absolute_import
+
 import ddt
+import six
+from crum import set_current_request
 from django.conf import settings
 from mock import patch
-from crum import set_current_request
 
 from openedx.core.djangolib.testing.utils import get_mock_request
 from student.models import CourseEnrollment
@@ -35,7 +39,7 @@ class ZeroGradeTest(GradeTestBase):
             chapter_grades = ZeroCourseGrade(self.request.user, course_data).chapter_grades
             for chapter in chapter_grades:
                 for section in chapter_grades[chapter]['sections']:
-                    for score in section.problem_scores.itervalues():
+                    for score in six.itervalues(section.problem_scores):
                         self.assertEqual(score.earned, 0)
                         self.assertEqual(score.first_attempted, None)
                     self.assertEqual(section.all_total.earned, 0)
diff --git a/lms/djangoapps/grades/tests/test_course_grade_factory.py b/lms/djangoapps/grades/tests/test_course_grade_factory.py
index 2a64c2b0fd..40b593c835 100644
--- a/lms/djangoapps/grades/tests/test_course_grade_factory.py
+++ b/lms/djangoapps/grades/tests/test_course_grade_factory.py
@@ -1,16 +1,18 @@
 """
 Tests for the CourseGradeFactory class.
 """
+from __future__ import absolute_import
+
 import itertools
 
 import ddt
-from courseware.access import has_access
 from django.conf import settings
-from lms.djangoapps.grades.config.tests.utils import persistent_grades_feature_flags
 from mock import patch
-from openedx.core.djangoapps.content.block_structure.factory import BlockStructureFactory
 from six import text_type
 
+from courseware.access import has_access
+from lms.djangoapps.grades.config.tests.utils import persistent_grades_feature_flags
+from openedx.core.djangoapps.content.block_structure.factory import BlockStructureFactory
 from student.tests.factories import UserFactory
 from xmodule.modulestore.tests.django_utils import SharedModuleStoreTestCase
 from xmodule.modulestore.tests.factories import CourseFactory
diff --git a/lms/djangoapps/grades/tests/test_models.py b/lms/djangoapps/grades/tests/test_models.py
index bd99823f6c..e174ab2bc6 100644
--- a/lms/djangoapps/grades/tests/test_models.py
+++ b/lms/djangoapps/grades/tests/test_models.py
@@ -1,6 +1,8 @@
 """
 Unit tests for grades models.
 """
+from __future__ import absolute_import
+
 import json
 from base64 import b64encode
 from collections import OrderedDict
@@ -9,6 +11,7 @@ from hashlib import sha1
 
 import ddt
 import pytz
+import six
 from django.db.utils import IntegrityError
 from django.test import TestCase
 from django.utils.timezone import now
@@ -46,7 +49,7 @@ class BlockRecordListTestCase(TestCase):
 
     def test_empty_block_record_set(self):
         empty_json = u'{"blocks":[],"course_key":"%s","version":%s}' % (
-            unicode(self.course_key),
+            six.text_type(self.course_key),
             BLOCK_RECORD_LIST_VERSION,
         )
 
@@ -150,15 +153,15 @@ class VisibleBlocksTest(GradesModelTestCase):
         vblocks = self._create_block_record_list([self.record_a])
         list_of_block_dicts = [self.record_a._asdict()]
         for block_dict in list_of_block_dicts:
-            block_dict['locator'] = unicode(block_dict['locator'])  # BlockUsageLocator is not json-serializable
+            block_dict['locator'] = six.text_type(block_dict['locator'])  # BlockUsageLocator is not json-serializable
         expected_data = {
             'blocks': [{
-                'locator': unicode(self.record_a.locator),
+                'locator': six.text_type(self.record_a.locator),
                 'raw_possible': 10,
                 'weight': 1,
                 'graded': self.record_a.graded,
             }],
-            'course_key': unicode(self.record_a.locator.course_key),
+            'course_key': six.text_type(self.record_a.locator.course_key),
             'version': BLOCK_RECORD_LIST_VERSION,
         }
         expected_json = json.dumps(expected_data, separators=(',', ':'), sort_keys=True)
@@ -334,19 +337,19 @@ class PersistentSubsectionGradeTest(GradesModelTestCase):
         tracker_mock.emit.assert_called_with(
             u'edx.grades.subsection.grade_calculated',
             {
-                'user_id': unicode(grade.user_id),
-                'course_id': unicode(grade.course_id),
-                'block_id': unicode(grade.usage_key),
-                'course_version': unicode(grade.course_version),
+                'user_id': six.text_type(grade.user_id),
+                'course_id': six.text_type(grade.course_id),
+                'block_id': six.text_type(grade.usage_key),
+                'course_version': six.text_type(grade.course_version),
                 'weighted_total_earned': grade.earned_all,
                 'weighted_total_possible': grade.possible_all,
                 'weighted_graded_earned': grade.earned_graded,
                 'weighted_graded_possible': grade.possible_graded,
-                'first_attempted': unicode(grade.first_attempted),
-                'subtree_edited_timestamp': unicode(grade.subtree_edited_timestamp),
-                'event_transaction_id': unicode(get_event_transaction_id()),
-                'event_transaction_type': unicode(get_event_transaction_type()),
-                'visible_blocks_hash': unicode(grade.visible_blocks_id),
+                'first_attempted': six.text_type(grade.first_attempted),
+                'subtree_edited_timestamp': six.text_type(grade.subtree_edited_timestamp),
+                'event_transaction_id': six.text_type(get_event_transaction_id()),
+                'event_transaction_type': six.text_type(get_event_transaction_type()),
+                'visible_blocks_hash': six.text_type(grade.visible_blocks_id),
             }
         )
 
@@ -481,14 +484,14 @@ class PersistentCourseGradesTest(GradesModelTestCase):
         tracker_mock.emit.assert_called_with(
             u'edx.grades.course.grade_calculated',
             {
-                'user_id': unicode(grade.user_id),
-                'course_id': unicode(grade.course_id),
-                'course_version': unicode(grade.course_version),
+                'user_id': six.text_type(grade.user_id),
+                'course_id': six.text_type(grade.course_id),
+                'course_version': six.text_type(grade.course_version),
                 'percent_grade': grade.percent_grade,
-                'letter_grade': unicode(grade.letter_grade),
-                'course_edited_timestamp': unicode(grade.course_edited_timestamp),
-                'event_transaction_id': unicode(get_event_transaction_id()),
-                'event_transaction_type': unicode(get_event_transaction_type()),
-                'grading_policy_hash': unicode(grade.grading_policy_hash),
+                'letter_grade': six.text_type(grade.letter_grade),
+                'course_edited_timestamp': six.text_type(grade.course_edited_timestamp),
+                'event_transaction_id': six.text_type(get_event_transaction_id()),
+                'event_transaction_type': six.text_type(get_event_transaction_type()),
+                'grading_policy_hash': six.text_type(grade.grading_policy_hash),
             }
         )
diff --git a/lms/djangoapps/grades/tests/test_scores.py b/lms/djangoapps/grades/tests/test_scores.py
index 9ac80481a0..c067ca0cf6 100644
--- a/lms/djangoapps/grades/tests/test_scores.py
+++ b/lms/djangoapps/grades/tests/test_scores.py
@@ -1,6 +1,8 @@
 """
 Tests for grades.scores module.
 """
+from __future__ import absolute_import
+
 import itertools
 # pylint: disable=protected-access
 from collections import namedtuple
diff --git a/lms/djangoapps/grades/tests/test_services.py b/lms/djangoapps/grades/tests/test_services.py
index 7d793b88c6..fdec8d49c3 100644
--- a/lms/djangoapps/grades/tests/test_services.py
+++ b/lms/djangoapps/grades/tests/test_services.py
@@ -1,18 +1,23 @@
 """
 Grades Service Tests
 """
+from __future__ import absolute_import
+
 from datetime import datetime
+
 import ddt
 import pytz
+import six
 from freezegun import freeze_time
+from mock import call, patch
+
 from lms.djangoapps.grades.constants import GradeOverrideFeatureEnum
 from lms.djangoapps.grades.models import (
     PersistentSubsectionGrade,
     PersistentSubsectionGradeOverride,
-    PersistentSubsectionGradeOverrideHistory,
+    PersistentSubsectionGradeOverrideHistory
 )
 from lms.djangoapps.grades.services import GradesService
-from mock import patch, call
 from student.tests.factories import UserFactory
 from xmodule.modulestore.tests.django_utils import ModuleStoreTestCase
 from xmodule.modulestore.tests.factories import CourseFactory, ItemFactory
@@ -107,8 +112,8 @@ class GradesServiceTests(ModuleStoreTestCase):
         # test with id strings as parameters instead
         self.assertDictEqual(self.subsection_grade_to_dict(self.service.get_subsection_grade(
             user_id=self.user.id,
-            course_key_or_id=unicode(self.course.id),
-            usage_key_or_id=unicode(self.subsection.location)
+            course_key_or_id=six.text_type(self.course.id),
+            usage_key_or_id=six.text_type(self.subsection.location)
         )), {
             'earned_all': 6.0,
             'earned_graded': 5.0
@@ -136,7 +141,7 @@ class GradesServiceTests(ModuleStoreTestCase):
         # test with course key parameter as string instead
         self.assertDictEqual(self.subsection_grade_override_to_dict(self.service.get_subsection_grade_override(
             user_id=self.user.id,
-            course_key_or_id=unicode(self.course.id),
+            course_key_or_id=six.text_type(self.course.id),
             usage_key_or_id=self.subsection.location
         )), {
             'earned_all_override': override.earned_all_override,
@@ -190,8 +195,8 @@ class GradesServiceTests(ModuleStoreTestCase):
             call(
                 sender=None,
                 user_id=self.user.id,
-                course_id=unicode(self.course.id),
-                usage_id=unicode(self.subsection.location),
+                course_id=six.text_type(self.course.id),
+                usage_id=six.text_type(self.subsection.location),
                 only_if_higher=False,
                 modified=override_obj.modified,
                 score_deleted=False,
@@ -241,8 +246,8 @@ class GradesServiceTests(ModuleStoreTestCase):
             call(
                 sender=None,
                 user_id=self.user.id,
-                course_id=unicode(self.course.id),
-                usage_id=unicode(self.subsection_without_grade.location),
+                course_id=six.text_type(self.course.id),
+                usage_id=six.text_type(self.subsection_without_grade.location),
                 only_if_higher=False,
                 modified=override_obj.modified,
                 score_deleted=False,
@@ -270,8 +275,8 @@ class GradesServiceTests(ModuleStoreTestCase):
             call(
                 sender=None,
                 user_id=self.user.id,
-                course_id=unicode(self.course.id),
-                usage_id=unicode(self.subsection.location),
+                course_id=six.text_type(self.course.id),
+                usage_id=six.text_type(self.subsection.location),
                 only_if_higher=False,
                 modified=datetime.now().replace(tzinfo=pytz.UTC),
                 score_deleted=True,
diff --git a/lms/djangoapps/grades/tests/test_signals.py b/lms/djangoapps/grades/tests/test_signals.py
index bd20ce1793..31c564839e 100644
--- a/lms/djangoapps/grades/tests/test_signals.py
+++ b/lms/djangoapps/grades/tests/test_signals.py
@@ -1,6 +1,8 @@
 """
 Tests for the score change signals defined in the courseware models module.
 """
+from __future__ import absolute_import
+
 import re
 from datetime import datetime
 
@@ -8,8 +10,8 @@ import ddt
 import pytz
 from django.test import TestCase
 from mock import MagicMock, patch
-
 from submissions.models import score_reset, score_set
+
 from util.date_utils import to_timestamp
 
 from ..constants import ScoreDatabaseTableEnum
@@ -17,7 +19,7 @@ from ..signals.handlers import (
     disconnect_submissions_signal_receiver,
     problem_raw_score_changed_handler,
     submissions_score_reset_handler,
-    submissions_score_set_handler,
+    submissions_score_set_handler
 )
 from ..signals.signals import PROBLEM_RAW_SCORE_CHANGED
 
diff --git a/lms/djangoapps/grades/tests/test_subsection_grade.py b/lms/djangoapps/grades/tests/test_subsection_grade.py
index f1cfdfe1d7..2f903491d9 100644
--- a/lms/djangoapps/grades/tests/test_subsection_grade.py
+++ b/lms/djangoapps/grades/tests/test_subsection_grade.py
@@ -1,12 +1,14 @@
 """
 Tests of the SubsectionGrade classes.
 """
+from __future__ import absolute_import
+
 from ddt import data, ddt, unpack
 
 from ..models import PersistentSubsectionGrade
 from ..subsection_grade import CreateSubsectionGrade, ReadSubsectionGrade
-from .utils import mock_get_score
 from .base import GradeTestBase
+from .utils import mock_get_score
 
 
 @ddt
diff --git a/lms/djangoapps/grades/tests/test_subsection_grade_factory.py b/lms/djangoapps/grades/tests/test_subsection_grade_factory.py
index f038642f52..9e9fd3b5d8 100644
--- a/lms/djangoapps/grades/tests/test_subsection_grade_factory.py
+++ b/lms/djangoapps/grades/tests/test_subsection_grade_factory.py
@@ -1,19 +1,18 @@
 """
 Tests for the SubsectionGradeFactory class.
 """
+from __future__ import absolute_import
+
 import ddt
-from mock import patch
 from django.conf import settings
+from mock import patch
 
 from courseware.tests.test_submitting_problems import ProblemSubmissionTestMixin
 from lms.djangoapps.grades.config.tests.utils import persistent_grades_feature_flags
 from student.tests.factories import UserFactory
 
 from ..constants import GradeOverrideFeatureEnum
-from ..models import (
-    PersistentSubsectionGrade,
-    PersistentSubsectionGradeOverride,
-)
+from ..models import PersistentSubsectionGrade, PersistentSubsectionGradeOverride
 from ..subsection_grade_factory import ZeroSubsectionGrade
 from .base import GradeTestBase
 from .utils import mock_get_score
diff --git a/lms/djangoapps/grades/tests/test_tasks.py b/lms/djangoapps/grades/tests/test_tasks.py
index 64b4c214b9..8c64d89a17 100644
--- a/lms/djangoapps/grades/tests/test_tasks.py
+++ b/lms/djangoapps/grades/tests/test_tasks.py
@@ -2,6 +2,8 @@
 Tests for the functionality and infrastructure of grades tasks.
 """
 
+from __future__ import absolute_import
+
 import itertools
 from collections import OrderedDict
 from contextlib import contextmanager
@@ -14,10 +16,11 @@ from django.conf import settings
 from django.db.utils import IntegrityError
 from django.utils import timezone
 from mock import MagicMock, patch
+from six.moves import range
 
 from lms.djangoapps.grades import tasks
 from lms.djangoapps.grades.config.models import PersistentGradesEnabledFlag
-from lms.djangoapps.grades.config.waffle import waffle_flags, ENFORCE_FREEZE_GRADE_AFTER_COURSE_END
+from lms.djangoapps.grades.config.waffle import ENFORCE_FREEZE_GRADE_AFTER_COURSE_END, waffle_flags
 from lms.djangoapps.grades.constants import ScoreDatabaseTableEnum
 from lms.djangoapps.grades.models import PersistentCourseGrade, PersistentSubsectionGrade
 from lms.djangoapps.grades.services import GradesService
@@ -41,7 +44,6 @@ from xmodule.modulestore.django import modulestore
 from xmodule.modulestore.tests.django_utils import ModuleStoreTestCase
 from xmodule.modulestore.tests.factories import CourseFactory, ItemFactory, check_mongo_calls
 
-
 from .utils import mock_get_score
 
 
@@ -90,8 +92,8 @@ class HasCourseWithProblemsMixin(object):
             ('weighted_possible', 2.0),
             ('user_id', self.user.id),
             ('anonymous_user_id', 5),
-            ('course_id', unicode(self.course.id)),
-            ('usage_id', unicode(self.problem.location)),
+            ('course_id', six.text_type(self.course.id)),
+            ('usage_id', six.text_type(self.problem.location)),
             ('only_if_higher', None),
             ('modified', self.frozen_now_datetime),
             ('score_db_table', ScoreDatabaseTableEnum.courseware_student_module),
@@ -101,13 +103,13 @@ class HasCourseWithProblemsMixin(object):
 
         self.recalculate_subsection_grade_kwargs = OrderedDict([
             ('user_id', self.user.id),
-            ('course_id', unicode(self.course.id)),
-            ('usage_id', unicode(self.problem.location)),
+            ('course_id', six.text_type(self.course.id)),
+            ('usage_id', six.text_type(self.problem.location)),
             ('anonymous_user_id', 5),
             ('only_if_higher', None),
             ('expected_modified_time', self.frozen_now_timestamp),
             ('score_deleted', False),
-            ('event_transaction_id', unicode(get_event_transaction_id())),
+            ('event_transaction_id', six.text_type(get_event_transaction_id())),
             ('event_transaction_type', u'edx.grades.problem.submitted'),
             ('score_db_table', ScoreDatabaseTableEnum.courseware_student_module),
         ])
@@ -424,12 +426,12 @@ class ComputeGradesForCourseTest(HasCourseWithProblemsMixin, ModuleStoreTestCase
 
     def setUp(self):
         super(ComputeGradesForCourseTest, self).setUp()
-        self.users = [UserFactory.create() for _ in xrange(12)]
+        self.users = [UserFactory.create() for _ in range(12)]
         self.set_up_course()
         for user in self.users:
             CourseEnrollment.enroll(user, self.course.id)
 
-    @ddt.data(*xrange(0, 12, 3))
+    @ddt.data(*range(0, 12, 3))
     def test_behavior(self, batch_size):
         with mock_get_score(1, 2):
             result = compute_grades_for_course_v2.delay(
@@ -447,7 +449,7 @@ class ComputeGradesForCourseTest(HasCourseWithProblemsMixin, ModuleStoreTestCase
             min(batch_size, 8)  # No more than 8 due to offset
         )
 
-    @ddt.data(*xrange(1, 12, 3))
+    @ddt.data(*range(1, 12, 3))
     def test_course_task_args(self, test_batch_size):
         offset_expected = 0
         for course_key, offset, batch_size in _course_task_args(
@@ -513,7 +515,7 @@ class FreezeGradingAfterCourseEndTest(HasCourseWithProblemsMixin, ModuleStoreTes
     """
     def setUp(self):
         super(FreezeGradingAfterCourseEndTest, self).setUp()
-        self.users = [UserFactory.create() for _ in xrange(12)]
+        self.users = [UserFactory.create() for _ in range(12)]
         self.user = self.users[0]
         self.freeze_grade_flag = waffle_flags()[ENFORCE_FREEZE_GRADE_AFTER_COURSE_END]
 
diff --git a/lms/djangoapps/grades/tests/test_transformer.py b/lms/djangoapps/grades/tests/test_transformer.py
index f90fdaee7f..903241b40d 100644
--- a/lms/djangoapps/grades/tests/test_transformer.py
+++ b/lms/djangoapps/grades/tests/test_transformer.py
@@ -2,12 +2,16 @@
 Test the behavior of the GradesTransformer
 """
 
+from __future__ import absolute_import
+
 import datetime
 import random
 from copy import deepcopy
 
 import ddt
 import pytz
+import six
+from six.moves import range
 
 from lms.djangoapps.course_blocks.api import get_course_blocks
 from lms.djangoapps.course_blocks.transformers.tests.helpers import CourseStructureTestCase
@@ -214,7 +218,7 @@ class GradesTransformerTestCase(CourseStructureTestCase):
         }
         blocks = self.build_complicated_hypothetical_course()
         block_structure = get_course_blocks(self.student, blocks[u'course'].location, self.transformers)
-        for block_ref, expected_subsections in expected_subsections.iteritems():
+        for block_ref, expected_subsections in six.iteritems(expected_subsections):
             actual_subsections = block_structure.get_transformer_block_field(
                 blocks[block_ref].location,
                 self.TRANSFORMER_CLASS_TO_TEST,
@@ -427,7 +431,7 @@ class MultiProblemModulestoreAccessTestCase(CourseStructureTestCase, SharedModul
                 u'#children': [],
             },
         ]
-        for problem_number in xrange(random.randrange(10, 20)):
+        for problem_number in range(random.randrange(10, 20)):
             course[0][u'#children'].append(
                 {
                     u'metadata': {
diff --git a/lms/djangoapps/grades/tests/utils.py b/lms/djangoapps/grades/tests/utils.py
index f02fde8b48..a0b97b8ab1 100644
--- a/lms/djangoapps/grades/tests/utils.py
+++ b/lms/djangoapps/grades/tests/utils.py
@@ -1,11 +1,13 @@
 """
 Utilities for grades related tests
 """
+from __future__ import absolute_import
+
 from contextlib import contextmanager
 from datetime import datetime
 
 import pytz
-from mock import patch, MagicMock
+from mock import MagicMock, patch
 
 from courseware.model_data import FieldDataCache
 from courseware.module_render import get_module