INCR-108 (#20058)

* INCR-108: Run python-modernize on openedx/core/lib

* Fixed urlencode import

* Fixed diff quality warnings and six.string_types error

* Fixed pickle import

* Fixed iteritems import

* Fixed ungrouped imports

* Fixed six.moves import issues

openedx/core/lib/api/authentication.py

@@ -1,5 +1,6 @@
 """ Common Authentication Handlers used across projects. """
 
+from __future__ import absolute_import
 import logging
 
 import django.utils.timezone

openedx/core/lib/api/fields.py

@@ -1,4 +1,5 @@
 """Fields useful for edX API implementations."""
+from __future__ import absolute_import
 from rest_framework.serializers import Field, URLField
 
 

openedx/core/lib/api/mixins.py

@@ -1,6 +1,7 @@
 """
 Django Rest Framework view mixins.
 """
+from __future__ import absolute_import
 from django.core.exceptions import ValidationError
 from django.http import Http404
 from rest_framework import status

openedx/core/lib/api/parsers.py

@@ -7,6 +7,7 @@ desired parsers.  See http://www.django-rest-framework.org/api-guide/parsers/
 for details.
 """
 
+from __future__ import absolute_import
 from rest_framework.exceptions import ParseError, UnsupportedMediaType
 from rest_framework.parsers import FileUploadParser, JSONParser
 

openedx/core/lib/api/permissions.py

@@ -2,6 +2,7 @@
 API library for Django REST Framework permissions-oriented workflows
 """
 
+from __future__ import absolute_import
 from django.conf import settings
 from django.http import Http404
 from opaque_keys import InvalidKeyError

openedx/core/lib/api/serializers.py

@@ -2,9 +2,11 @@
 Serializers to be used in APIs.
 """
 
+from __future__ import absolute_import
 from opaque_keys import InvalidKeyError
 from opaque_keys.edx.keys import CourseKey, UsageKey
 from rest_framework import serializers
+import six
 
 
 class CollapsedReferenceSerializer(serializers.HyperlinkedModelSerializer):
@@ -46,7 +48,7 @@ class CourseKeyField(serializers.Field):
 
     def to_representation(self, data):
         """Convert a course key to unicode. """
-        return unicode(data)
+        return six.text_type(data)
 
     def to_internal_value(self, data):
         """Convert unicode to a course key. """
@@ -61,7 +63,7 @@ class UsageKeyField(serializers.Field):
 
     def to_representation(self, data):
         """Convert a usage key to unicode. """
-        return unicode(data)
+        return six.text_type(data)
 
     def to_internal_value(self, data):
         """Convert unicode to a usage key. """

openedx/core/lib/api/test_utils.py

@@ -1,6 +1,7 @@
 """
 Helpers for API tests.
 """
+from __future__ import absolute_import
 import base64
 import json
 import re

openedx/core/lib/api/tests/mixins.py

@@ -1,6 +1,7 @@
 """
 Mixins for JWT auth tests.
 """
+from __future__ import absolute_import
 from time import time
 
 from django.conf import settings

openedx/core/lib/api/tests/test_authentication.py

@@ -5,6 +5,7 @@ Tests for OAuth2.  This module is copied from django-rest-framework-oauth
 
 from __future__ import unicode_literals
 
+from __future__ import absolute_import
 import itertools
 import json
 import unittest

openedx/core/lib/api/tests/test_exceptions.py

@@ -1,9 +1,11 @@
 """
 Test Custom Exceptions
 """
+from __future__ import absolute_import
 import ddt
 from django.test import TestCase
 from rest_framework import exceptions as drf_exceptions
+import six
 
 
 @ddt.ddt
@@ -15,7 +17,7 @@ class TestDictExceptionsAllowDictDetails(TestCase):
     def test_drf_errors_are_not_coerced_to_strings(self):
         # Demonstrate that dictionaries in exceptions are not coerced to strings.
         exc = drf_exceptions.AuthenticationFailed({u'error_code': -1})
-        self.assertNotIsInstance(exc.detail, basestring)
+        self.assertNotIsInstance(exc.detail, six.string_types)
 
     @ddt.data(
         drf_exceptions.AuthenticationFailed,

openedx/core/lib/api/tests/test_fields.py

@@ -1,4 +1,5 @@
 """ Tests for custom DRF fields. """
+from __future__ import absolute_import
 import ddt
 from django.test import TestCase
 

openedx/core/lib/api/tests/test_parsers.py

@@ -2,6 +2,7 @@
 TestCases verifying proper behavior of custom DRF request parsers.
 """
 
+from __future__ import absolute_import
 from collections import namedtuple
 from io import BytesIO
 

openedx/core/lib/api/tests/test_permissions.py

@@ -1,5 +1,6 @@
 """ Tests for API permissions classes. """
 
+from __future__ import absolute_import
 import ddt
 from django.contrib.auth.models import AnonymousUser
 from django.http import Http404

openedx/core/lib/api/view_utils.py

@@ -1,6 +1,7 @@
 """
 Utilities related to API views
 """
+from __future__ import absolute_import
 from collections import Sequence
 from django.core.exceptions import NON_FIELD_ERRORS, ObjectDoesNotExist, ValidationError
 from django.http import Http404
@@ -14,7 +15,7 @@ from rest_framework.mixins import RetrieveModelMixin, UpdateModelMixin
 from rest_framework.permissions import IsAuthenticated
 from rest_framework.request import clone_request
 from rest_framework.response import Response
-from six import text_type
+from six import text_type, iteritems
 
 from openedx.core.lib.api.authentication import OAuth2AuthenticationAllowInactiveUser
 from openedx.core.lib.api.permissions import IsUserInUrl
@@ -129,7 +130,7 @@ def add_serializer_errors(serializer, data, field_errors):
     """Adds errors from serializer validation to field_errors. data is the original data to deserialize."""
     if not serializer.is_valid():
         errors = serializer.errors
-        for key, error in errors.iteritems():
+        for key, error in iteritems(errors):
             field_errors[key] = {
                 'developer_message': u"Value '{field_value}' is not valid for field '{field_name}': {error}".format(
                     field_value=data.get(key, ''), field_name=key, error=error

openedx/core/lib/cache_utils.py

@@ -1,15 +1,18 @@
 """
 Utilities related to caching.
 """
+from __future__ import absolute_import
 import collections
-import cPickle as pickle
 import functools
 import itertools
 import zlib
+import wrapt
 
 from django.utils.encoding import force_text
 from edx_django_utils.cache import RequestCache
-import wrapt
+from six import iteritems
+from six.moves import map
+from six.moves import cPickle as pickle
 
 
 def request_cached(namespace=None, arg_map_function=None, request_cache_getter=None):
@@ -85,10 +88,10 @@ def _func_call_cache_key(func, arg_map_function, *args, **kwargs):
     """
     arg_map_function = arg_map_function or force_text
 
-    converted_args = map(arg_map_function, args)
-    converted_kwargs = map(arg_map_function, _sorted_kwargs_list(kwargs))
+    converted_args = list(map(arg_map_function, args))
+    converted_kwargs = list(map(arg_map_function, _sorted_kwargs_list(kwargs)))
 
-    cache_keys = [func.__module__, func.func_name] + converted_args + converted_kwargs
+    cache_keys = [func.__module__, func.__name__] + converted_args + converted_kwargs
     return u'.'.join(cache_keys)
 
 
@@ -96,7 +99,7 @@ def _sorted_kwargs_list(kwargs):
     """
     Returns a unique and deterministic ordered list from the given kwargs.
     """
-    sorted_kwargs = sorted(kwargs.iteritems())
+    sorted_kwargs = sorted(iteritems(kwargs))
     sorted_kwargs_list = list(itertools.chain(*sorted_kwargs))
     return sorted_kwargs_list
 

openedx/core/lib/celery/routers.py

@@ -3,20 +3,20 @@ Custom routers used by both lms and cms when routing tasks to worker queues.
 
 For more, see https://celery.readthedocs.io/en/latest/userguide/routing.html#routers
 """
+from __future__ import absolute_import
 import logging
 from abc import ABCMeta, abstractproperty
 
 from django.conf import settings
+import six
 
 log = logging.getLogger(__name__)
 
 
-class AlternateEnvironmentRouter(object):
+class AlternateEnvironmentRouter(six.with_metaclass(ABCMeta, object)):
     """
     A custom Router class for use in routing celery tasks to non-default queues.
     """
-    # this is an abstract base class, implementations must provide alternate_env_tasks
-    __metaclass__ = ABCMeta
 
     @abstractproperty
     def alternate_env_tasks(self):

openedx/core/lib/celery/task_utils.py

@@ -1,3 +1,7 @@
+"""
+    Middleware utilities
+"""
+from __future__ import absolute_import
 from contextlib import contextmanager
 
 from crum import CurrentRequestUserMiddleware

openedx/core/lib/command_utils.py

@@ -2,6 +2,7 @@
 Useful utilities for management commands.
 """
 
+from __future__ import absolute_import
 from django.core.management.base import CommandError
 from opaque_keys import InvalidKeyError
 from opaque_keys.edx.keys import CourseKey

openedx/core/lib/course_tabs.py

@@ -1,6 +1,7 @@
 """
 Tabs for courseware.
 """
+from __future__ import absolute_import
 from openedx.core.lib.plugins import PluginManager
 
 # Stevedore extension point namespaces
@@ -39,6 +40,6 @@ class CourseTabPluginManager(PluginManager):
                 return 0
             else:
                 return 1
-        tab_types = cls.get_available_plugins().values()
+        tab_types = list(cls.get_available_plugins().values())
         tab_types.sort(cmp=compare_tabs)
         return tab_types

openedx/core/lib/courses.py

@@ -1,6 +1,7 @@
 """
 Common utility functions related to courses.
 """
+from __future__ import absolute_import
 from django import forms
 from django.conf import settings
 

openedx/core/lib/derived.py

@@ -4,6 +4,7 @@ via callable methods/lambdas. The derivation time can be controlled to happen af
 other settings have been set. The derived setting can also be overridden by setting the
 derived setting to an actual value.
 """
+from __future__ import absolute_import
 import six
 import sys
 

openedx/core/lib/django_require/staticstorage.py

@@ -2,6 +2,7 @@
 :class:`~django_require.staticstorage.OptimizedCachedRequireJsStorage`
 """
 
+from __future__ import absolute_import
 from openedx.core.storage import PipelineForgivingStorage
 from require.storage import OptimizedFilesMixin
 

openedx/core/lib/edx_api_utils.py

@@ -1,6 +1,7 @@
 """Helper functions to get data from APIs"""
 from __future__ import unicode_literals
 
+from __future__ import absolute_import
 import logging
 
 from django.core.cache import cache

openedx/core/lib/exceptions.py

@@ -1,6 +1,7 @@
 """
 Common Purpose Errors
 """
+from __future__ import absolute_import
 from django.core.exceptions import ObjectDoesNotExist
 
 

openedx/core/lib/extract_tar.py

@@ -5,6 +5,7 @@ be, or symlink to a file that is, outside of the directory extracted in.
 Adapted from:
 http://stackoverflow.com/questions/10060069/safely-extract-zip-or-tar-using-python
 """
+from __future__ import absolute_import
 import logging
 from os.path import join as joinpath
 from os.path import abspath, dirname, realpath

openedx/core/lib/gating/api.py

@@ -1,6 +1,7 @@
 """
 API for the gating djangoapp
 """
+from __future__ import absolute_import
 import json
 import logging
 
@@ -19,6 +20,7 @@ from util import milestones_helpers
 from xblock.completable import XBlockCompletionMode as CompletionMode
 from xmodule.modulestore.django import modulestore
 from xmodule.modulestore.exceptions import ItemNotFoundError
+import six
 
 log = logging.getLogger(__name__)
 
@@ -162,7 +164,7 @@ def get_prerequisites(course_key):
         milestone = milestones_by_block_id.get(block.location.block_id)
         if milestone:
             milestone['block_display_name'] = block.display_name
-            milestone['block_usage_key'] = unicode(block.location)
+            milestone['block_usage_key'] = six.text_type(block.location)
             result.append(milestone)
 
     return result
@@ -182,7 +184,7 @@ def add_prerequisite(course_key, prereq_content_key):
     """
     milestone = milestones_api.add_milestone(
         {
-            'name': _(u'Gating milestone for {usage_key}').format(usage_key=unicode(prereq_content_key)),
+            'name': _(u'Gating milestone for {usage_key}').format(usage_key=six.text_type(prereq_content_key)),
             'namespace': "{usage_key}{qualifier}".format(
                 usage_key=prereq_content_key,
                 qualifier=GATING_NAMESPACE_QUALIFIER

openedx/core/lib/gating/services.py

@@ -1,6 +1,7 @@
 """
 A wrapper class to communicate with Gating api
 """
+from __future__ import absolute_import
 from . import api as gating_api
 
 

openedx/core/lib/gating/tests/test_api.py

@@ -1,7 +1,7 @@
 """
 Tests for the gating API
 """
-from __future__ import unicode_literals
+from __future__ import absolute_import, unicode_literals
 
 import unittest
 
@@ -24,6 +24,7 @@ from xmodule.modulestore.tests.factories import CourseFactory, ItemFactory
 from openedx.core.lib.gating import api as gating_api
 from openedx.core.lib.gating.exceptions import GatingValidationError
 from student.tests.factories import UserFactory
+import six
 
 
 @ddt
@@ -78,7 +79,7 @@ class TestGatingApi(ModuleStoreTestCase, MilestonesTestCaseMixin):
 
         self.generic_milestone = {
             'name': 'Test generic milestone',
-            'namespace': unicode(self.seq1.location),
+            'namespace': six.text_type(self.seq1.location),
         }
 
     @patch('openedx.core.lib.gating.api.log.warning')
@@ -148,7 +149,7 @@ class TestGatingApi(ModuleStoreTestCase, MilestonesTestCaseMixin):
         prereqs = gating_api.get_prerequisites(self.course.id)
         self.assertEqual(len(prereqs), 1)
         self.assertEqual(prereqs[0]['block_display_name'], self.seq1.display_name)
-        self.assertEqual(prereqs[0]['block_usage_key'], unicode(self.seq1.location))
+        self.assertEqual(prereqs[0]['block_usage_key'], six.text_type(self.seq1.location))
         self.assertTrue(gating_api.is_prerequisite(self.course.id, self.seq1.location))
 
         gating_api.remove_prerequisite(self.seq1.location)
@@ -165,7 +166,7 @@ class TestGatingApi(ModuleStoreTestCase, MilestonesTestCaseMixin):
         prereq_content_key, min_score, min_completion = gating_api.get_required_content(
             self.course.id, self.seq2.location
         )
-        self.assertEqual(prereq_content_key, unicode(self.seq1.location))
+        self.assertEqual(prereq_content_key, six.text_type(self.seq1.location))
         self.assertEqual(min_score, 100)
         self.assertEqual(min_completion, 100)
 
@@ -194,7 +195,7 @@ class TestGatingApi(ModuleStoreTestCase, MilestonesTestCaseMixin):
         milestone = milestones_api.get_course_content_milestones(self.course.id, self.seq2.location, 'requires')[0]
 
         self.assertEqual(gating_api.get_gated_content(self.course, staff), [])
-        self.assertEqual(gating_api.get_gated_content(self.course, student), [unicode(self.seq2.location)])
+        self.assertEqual(gating_api.get_gated_content(self.course, student), [six.text_type(self.seq2.location)])
 
         milestones_api.add_user_milestone({'id': student.id}, milestone)
 

openedx/core/lib/graph_traversals.py

@@ -109,6 +109,7 @@ to each node's parents.  This requires additional storage space, which
 could be eliminated if DAGs are not supported.
 
 """
+from __future__ import absolute_import
 from collections import deque
 
 
@@ -219,7 +220,7 @@ def traverse_post_order(start_node, get_children, filter_func=None):
 
         # See if there are any additional children for this node.
         try:
-            next_child = current.children.next()
+            next_child = next(current.children)
 
         except StopIteration:
             # Since there are no children left, visit the node and

openedx/core/lib/html_to_text.py

@@ -1,4 +1,5 @@
 """Provides a function to convert html to plaintext."""
+from __future__ import absolute_import
 import logging
 from subprocess import PIPE, Popen
 

openedx/core/lib/json_utils.py

@@ -2,9 +2,11 @@
 Helpers for json serialization
 """
 
+from __future__ import absolute_import
 import datetime
 from django.core.serializers.json import DjangoJSONEncoder
 from opaque_keys.edx.keys import CourseKey, UsageKey
+import six
 
 
 class EdxJSONEncoder(DjangoJSONEncoder):
@@ -16,7 +18,7 @@ class EdxJSONEncoder(DjangoJSONEncoder):
     """
     def default(self, o):  # pylint: disable=method-hidden
         if isinstance(o, (CourseKey, UsageKey)):
-            return unicode(o)
+            return six.text_type(o)
         elif isinstance(o, datetime.datetime):
             if o.tzinfo is not None:
                 if o.utcoffset() is None:

openedx/core/lib/license/mixin.py

@@ -1,6 +1,7 @@
 """
 License mixin for XBlocks and XModules
 """
+from __future__ import absolute_import
 from xblock.core import XBlockMixin
 from xblock.fields import Scope, String
 

openedx/core/lib/log_utils.py

@@ -1,6 +1,7 @@
 """
 Helper functions for logging.
 """
+from __future__ import absolute_import
 import logging
 
 log = logging.getLogger(__name__)

openedx/core/lib/logsettings.py

@@ -1,5 +1,6 @@
 """Get log settings."""
 
+from __future__ import absolute_import
 import logging
 import platform
 import sys

openedx/core/lib/mail_utils.py

@@ -2,6 +2,7 @@
 Utilities related to mailing.
 """
 
+from __future__ import absolute_import
 import textwrap
 
 MAX_LINE_LENGTH = 900

openedx/core/lib/mobile_utils.py

@@ -2,6 +2,7 @@
 Common utilities related to the mobile apps.
 """
 
+from __future__ import absolute_import
 import re
 
 from django.conf import settings

openedx/core/lib/plugins.py

@@ -1,6 +1,7 @@
 """
 Adds support for first class plugins that can be added to the edX platform.
 """
+from __future__ import absolute_import
 from collections import OrderedDict
 
 from stevedore.extension import ExtensionManager

openedx/core/lib/request_utils.py

@@ -1,7 +1,8 @@
 """ Utility functions related to HTTP requests """
+from __future__ import absolute_import
 import logging
 import re
-from urlparse import urlparse
+from six.moves.urllib.parse import urlparse  # pylint: disable=import-error
 
 import crum
 from django.conf import settings
@@ -9,9 +10,9 @@ from django.utils.deprecation import MiddlewareMixin
 from django.test.client import RequestFactory
 
 from openedx.core.djangoapps.waffle_utils import WaffleFlag, WaffleFlagNamespace
+from openedx.core.djangoapps.site_configuration import helpers as configuration_helpers
 from opaque_keys import InvalidKeyError
 from opaque_keys.edx.keys import CourseKey
-from openedx.core.djangoapps.site_configuration import helpers as configuration_helpers
 
 try:
     import newrelic.agent
@@ -119,8 +120,8 @@ class CookieMetricsMiddleware(MiddlewareMixin):
         for name, size in cookie_names_to_size.items():
             metric_name = 'cookies.{}.size'.format(name)
             newrelic.agent.add_custom_parameter(metric_name, size)
-            log.debug("%s = %d", metric_name, size)
+            log.debug(u'%s = %d', metric_name, size)
 
         total_cookie_size = sum(cookie_names_to_size.values())
         newrelic.agent.add_custom_parameter('cookies_total_size', total_cookie_size)
-        log.debug("cookies_total_size = %d", total_cookie_size)
+        log.debug(u'cookies_total_size = %d', total_cookie_size)

openedx/core/lib/rooted_paths.py

@@ -1,5 +1,6 @@
 """Provides rooted_glob, for finding relative glob paths in another director."""
 
+from __future__ import absolute_import
 import glob2
 
 

openedx/core/lib/tempdir.py

@@ -1,5 +1,6 @@
 """Make temporary directories nicely."""
 
+from __future__ import absolute_import
 import atexit
 import os.path
 import shutil

openedx/core/lib/tests/assertions/events.py

@@ -1,7 +1,9 @@
 """Assertions related to event validation"""
 
+from __future__ import absolute_import
 import json
 import pprint
+import six
 
 
 def assert_event_matches(expected, actual, tolerate=None):
@@ -193,7 +195,7 @@ def parse_event_payload(event):
     Note that this may simply return the same event unchanged, or return a new copy of the event with the payload
     parsed. It will never modify the event in place.
     """
-    if 'event' in event and isinstance(event['event'], basestring):
+    if 'event' in event and isinstance(event['event'], six.string_types):
         event = event.copy()
         try:
             event['event'] = json.loads(event['event'])
@@ -217,8 +219,8 @@ def compare_structs(expected, actual, should_strict_compare=None, path=None):
     differences = []
 
     if isinstance(expected, dict) and isinstance(actual, dict):
-        expected_keys = frozenset(expected.keys())
-        actual_keys = frozenset(actual.keys())
+        expected_keys = frozenset(list(expected.keys()))
+        actual_keys = frozenset(list(actual.keys()))
 
         for key in expected_keys - actual_keys:
             differences.append(u'{0}: not found in actual'.format(_path_to_string(path + [key])))

openedx/core/lib/tests/test_cache_utils.py

@@ -2,6 +2,7 @@
 """
 Tests for cache_utils.py
 """
+from __future__ import absolute_import
 from unittest import TestCase
 
 import ddt
@@ -9,6 +10,7 @@ from mock import Mock
 
 from edx_django_utils.cache import RequestCache
 from openedx.core.lib.cache_utils import request_cached
+import six
 
 
 @ddt.ddt
@@ -175,7 +177,7 @@ class TestRequestCachedDecorator(TestCase):
             A dummy function that expects an str and unicode arguments.
             """
             assert isinstance(arg1, str), 'First parameter has to be of type `str`'
-            assert isinstance(arg2, unicode), 'Second parameter has to be of type `unicode`'
+            assert isinstance(arg2, six.text_type), 'Second parameter has to be of type `unicode`'
             return True
 
         self.assertTrue(dummy_function('Hello', u'World'), 'Should be callable with ASCII chars')
@@ -274,7 +276,7 @@ class TestRequestCachedDecorator(TestCase):
             """Simple wrapper to let us decorate our mock."""
             return to_be_wrapped(*args, **kwargs)
 
-        arg_map_function = lambda arg: unicode(arg == 1)
+        arg_map_function = lambda arg: six.text_type(arg == 1)
         wrapped = request_cached(arg_map_function=arg_map_function)(mock_wrapper)
 
         # This will be a miss, and make an underlying call.

openedx/core/lib/tests/test_command_utils.py

@@ -2,6 +2,7 @@
 Tests of management command utility code
 """
 
+from __future__ import absolute_import
 from unittest import TestCase
 
 import ddt

openedx/core/lib/tests/test_course_tab_api.py

@@ -2,6 +2,7 @@
 Tests for the plugin API
 """
 
+from __future__ import absolute_import
 from django.test import TestCase
 
 from openedx.core.lib.plugins import PluginError

openedx/core/lib/tests/test_course_tabs.py

@@ -1,5 +1,6 @@
 """ Tests of specific tabs. """
 
+from __future__ import absolute_import
 from unittest import TestCase
 
 from mock import Mock, patch

openedx/core/lib/tests/test_courses.py

@@ -2,6 +2,7 @@
 Tests for functionality in openedx/core/lib/courses.py.
 """
 
+from __future__ import absolute_import
 import ddt
 from django.test.utils import override_settings
 
@@ -9,6 +10,7 @@ from xmodule.modulestore import ModuleStoreEnum
 from xmodule.modulestore.tests.django_utils import ModuleStoreTestCase
 from xmodule.modulestore.tests.factories import CourseFactory
 
+import six
 from ..courses import course_image_url
 
 
@@ -28,7 +30,7 @@ class CourseImageTestCase(ModuleStoreTestCase):
         """Test image URL formatting."""
         course = CourseFactory.create()
         self.verify_url(
-            unicode(course.id.make_asset_key('asset', course.course_image)),
+            six.text_type(course.id.make_asset_key('asset', course.course_image)),
             course_image_url(course)
         )
 
@@ -37,7 +39,7 @@ class CourseImageTestCase(ModuleStoreTestCase):
         course_image = u'before_\N{SNOWMAN}_after.jpg'
         course = CourseFactory.create(course_image=course_image)
         self.verify_url(
-            unicode(course.id.make_asset_key('asset', course_image.replace(u'\N{SNOWMAN}', '_'))),
+            six.text_type(course.id.make_asset_key('asset', course_image.replace(u'\N{SNOWMAN}', '_'))),
             course_image_url(course)
         )
 
@@ -46,7 +48,7 @@ class CourseImageTestCase(ModuleStoreTestCase):
         course_image = u'before after.jpg'
         course = CourseFactory.create(course_image=u'before after.jpg')
         self.verify_url(
-            unicode(course.id.make_asset_key('asset', course_image.replace(" ", "_"))),
+            six.text_type(course.id.make_asset_key('asset', course_image.replace(" ", "_"))),
             course_image_url(course)
         )
 
@@ -69,7 +71,7 @@ class CourseImageTestCase(ModuleStoreTestCase):
         banner_image = u'banner_image.jpg'
         course = CourseFactory.create(banner_image=banner_image)
         self.verify_url(
-            unicode(course.id.make_asset_key('asset', banner_image)),
+            six.text_type(course.id.make_asset_key('asset', banner_image)),
             course_image_url(course, 'banner_image')
         )
 
@@ -78,6 +80,6 @@ class CourseImageTestCase(ModuleStoreTestCase):
         thumbnail_image = u'thumbnail_image.jpg'
         course = CourseFactory.create(video_thumbnail_image=thumbnail_image)
         self.verify_url(
-            unicode(course.id.make_asset_key('asset', thumbnail_image)),
+            six.text_type(course.id.make_asset_key('asset', thumbnail_image)),
             course_image_url(course, 'video_thumbnail_image')
         )

openedx/core/lib/tests/test_derived.py

@@ -2,6 +2,7 @@
 Tests for derived.py
 """
 
+from __future__ import absolute_import
 import sys
 from unittest import TestCase
 from openedx.core.lib.derived import derived, derived_collection_entry, derive_settings, clear_for_tests

openedx/core/lib/tests/test_edx_api_utils.py

@@ -1,5 +1,6 @@
 """Tests covering edX API utilities."""
 # pylint: disable=missing-docstring
+from __future__ import absolute_import
 import json
 
 import httpretty

openedx/core/lib/tests/test_graph_traversals.py

@@ -2,9 +2,12 @@
 Tests for graph traversal generator functions.
 """
 
+from __future__ import absolute_import
 from collections import defaultdict
 from unittest import TestCase
 
+import six
+from six.moves import range
 from ..graph_traversals import traverse_post_order, traverse_pre_order, traverse_topologically
 
 
@@ -62,7 +65,7 @@ class TestGraphTraversals(TestCase):
                 will be [].
         """
         result = defaultdict(list)
-        for parent, children in parent_to_children_map.iteritems():
+        for parent, children in six.iteritems(parent_to_children_map):
             for child in children:
                 result[child].append(parent)
         return result

openedx/core/lib/tests/test_request_utils.py

@@ -1,5 +1,6 @@
 """Tests for request_utils module."""
 
+from __future__ import absolute_import
 import unittest
 
 from django.conf import settings

openedx/core/lib/tests/test_time_zone_utils.py

@@ -1,5 +1,6 @@
 """Tests covering time zone utilities."""
 
+from __future__ import absolute_import
 from django.test import TestCase
 from freezegun import freeze_time
 from pytz import timezone

openedx/core/lib/tests/test_url_utils.py

@@ -1,6 +1,7 @@
 """
 Tests for url_utils module.
 """
+from __future__ import absolute_import
 from ddt import data, ddt
 from django.test import TestCase
 

openedx/core/lib/tests/test_xblock_utils.py

@@ -9,7 +9,6 @@ import ddt
 from django.test.client import RequestFactory
 from mock import patch
 from web_fragments.fragment import Fragment
-from six import text_type
 
 from opaque_keys.edx.asides import AsideUsageKeyV1, AsideUsageKeyV2
 from openedx.core.lib.url_utils import quote_slashes
@@ -30,6 +29,7 @@ from xmodule.modulestore import ModuleStoreEnum
 from xmodule.modulestore.tests.django_utils import SharedModuleStoreTestCase
 from xmodule.modulestore.tests.factories import CourseFactory, ItemFactory
 from xmodule.modulestore.tests.test_asides import AsideTestType
+import six
 
 
 @ddt.ddt
@@ -106,7 +106,7 @@ class TestXblockUtils(SharedModuleStoreTestCase):
             view='baseview',
             frag=fragment,
             context={"wrap_xblock_data": {"custom-attribute": "custom-value"}},
-            usage_id_serializer=lambda usage_id: quote_slashes(unicode(usage_id)),
+            usage_id_serializer=lambda usage_id: quote_slashes(six.text_type(usage_id)),
             request_token=uuid.uuid1().get_hex()
         )
         self.assertIsInstance(test_wrap_output, Fragment)
@@ -248,4 +248,4 @@ class TestXBlockAside(SharedModuleStoreTestCase):
     @XBlockAside.register_temp_plugin(AsideTestType, 'test_aside')
     def test_get_aside(self):
         """test get aside success"""
-        assert get_aside_from_xblock(self.block, text_type("test_aside")) is not None
+        assert get_aside_from_xblock(self.block, six.text_type("test_aside")) is not None

openedx/core/lib/tests/tools.py

@@ -9,6 +9,7 @@ We define the ``__unittest`` symbol in their module namespace so unittest will
 skip them when printing tracebacks, just as it does for their corresponding
 methods in ``unittest`` proper.
 """
+from __future__ import absolute_import
 import re
 import unittest
 

openedx/core/lib/time_zone_utils.py

@@ -1,6 +1,7 @@
 """
 Utilities related to timezones
 """
+from __future__ import absolute_import
 from datetime import datetime
 
 from pytz import common_timezones, timezone, utc

openedx/core/lib/url_utils.py

@@ -1,6 +1,7 @@
 """
 Contains common utilities for URL escaping.
 """
+from __future__ import absolute_import
 import re
 
 

openedx/core/lib/xblock_builtin/__init__.py

@@ -4,6 +4,7 @@ Helper functions shared by built-in XBlocks.
 """
 
 
+from __future__ import absolute_import
 from django.conf import settings
 
 

openedx/core/lib/xblock_builtin/xblock_discussion/setup.py

@@ -2,6 +2,7 @@
 Setup for discussion-forum XBlock.
 """
 
+from __future__ import absolute_import
 import os
 from setuptools import find_packages, setup
 

openedx/core/lib/xblock_builtin/xblock_discussion/tests.py

@@ -1,5 +1,6 @@
 """ Tests for DiscussionXBLock"""
 from __future__ import print_function
+from __future__ import absolute_import
 from collections import namedtuple
 import ddt
 import itertools
@@ -14,6 +15,7 @@ from openedx.core.lib.xblock_builtin.xblock_discussion.xblock_discussion import
 from xblock.field_data import DictFieldData
 from xblock.fields import ScopeIds, UNIQUE_ID, NO_CACHE_VALUE
 from xblock.runtime import Runtime
+from six.moves import range
 
 
 def attribute_pair_repr(self):
@@ -37,7 +39,7 @@ def _random_string():
     """
     Generates random string
     """
-    return ''.join(random.choice(string.lowercase, ) for _ in xrange(12))
+    return ''.join(random.choice(string.lowercase, ) for _ in range(12))
 
 
 def _make_attribute_test_cases():

openedx/core/lib/xblock_builtin/xblock_discussion/xblock_discussion/__init__.py

@@ -2,9 +2,11 @@
 """
 Discussion XBlock
 """
+from __future__ import absolute_import
 import logging
-import urllib
-
+import six
+from six.moves import urllib
+from six.moves.urllib.parse import urlparse  # pylint: disable=import-error
 from django.contrib.staticfiles.storage import staticfiles_storage
 from django.urls import reverse
 from django.utils.translation import get_language_bidi
@@ -174,7 +176,7 @@ class DiscussionXBlock(XBlock, StudioEditableXBlockMixin, XmlParserMixin):
         login_msg = ''
 
         if not self.django_user.is_authenticated:
-            qs = urllib.urlencode({
+            qs = urllib.parse.urlencode({
                 'course_id': self.course_key,
                 'enrollment_action': 'enroll',
                 'email_opt_in': False,
@@ -252,7 +254,7 @@ class DiscussionXBlock(XBlock, StudioEditableXBlockMixin, XmlParserMixin):
         """
         Applies metadata translations for attributes stored on an inlined XML element.
         """
-        for old_attr, target_attr in cls.metadata_translations.iteritems():
+        for old_attr, target_attr in six.iteritems(cls.metadata_translations):
             if old_attr in node.attrib and hasattr(block, target_attr):
                 setattr(block, target_attr, node.attrib[old_attr])
 
@@ -274,6 +276,6 @@ class DiscussionXBlock(XBlock, StudioEditableXBlockMixin, XmlParserMixin):
         metadata = cls.load_metadata(definition_xml)
         cls.apply_policy(metadata, runtime.get_policy(block.scope_ids.usage_id))
 
-        for field_name, value in metadata.iteritems():
+        for field_name, value in six.iteritems(metadata):
             if field_name in block.fields:
                 setattr(block, field_name, value)

openedx/core/lib/xblock_pipeline/finder.py

@@ -1,6 +1,7 @@
 """
 Django pipeline finder for handling static assets required by XBlocks.
 """
+from __future__ import absolute_import
 import os
 from datetime import datetime
 

openedx/core/lib/xblock_utils/__init__.py

@@ -2,24 +2,24 @@
 Functions that can are used to modify XBlock fragments for use in the LMS and Studio
 """
 
+from __future__ import absolute_import
 import datetime
 import json
 import logging
-import markupsafe
 import re
-import static_replace
 import uuid
+import static_replace
+import markupsafe
 from lxml import html, etree
 from contracts import contract
 
 from django.conf import settings
-from django.contrib.staticfiles.storage import staticfiles_storage
 from django.urls import reverse
-from pytz import UTC
 from django.utils.html import escape
 from django.contrib.auth.models import User
+from django.contrib.staticfiles.storage import staticfiles_storage
+from pytz import UTC
 from edxmako.shortcuts import render_to_string
-from six import text_type
 from web_fragments.fragment import Fragment
 from xblock.core import XBlock
 from xblock.exceptions import InvalidScopeError
@@ -32,6 +32,8 @@ from xmodule.vertical_block import VerticalBlock
 from xmodule.x_module import shim_xmodule_js, XModuleDescriptor, XModule, PREVIEW_VIEWS, STUDIO_VIEW
 
 import webpack_loader.utils
+import six
+from six import text_type
 
 log = logging.getLogger(__name__)
 
@@ -142,7 +144,7 @@ def wrap_xblock(
         'classes': css_classes,
         'display_name': block.display_name_with_default_escaped,  # xss-lint: disable=python-deprecated-display-name
         'data_attributes': u' '.join(u'data-{}="{}"'.format(markupsafe.escape(key), markupsafe.escape(value))
-                                     for key, value in data.iteritems()),
+                                     for key, value in six.iteritems(data)),
     }
 
     if hasattr(frag, 'json_init_args') and frag.json_init_args is not None:
@@ -215,7 +217,7 @@ def wrap_xblock_aside(
         'content': frag.content,
         'classes': css_classes,
         'data_attributes': u' '.join(u'data-{}="{}"'.format(markupsafe.escape(key), markupsafe.escape(value))
-                                     for key, value in data.iteritems()),
+                                     for key, value in six.iteritems(data)),
     }
 
     if hasattr(frag, 'json_init_args') and frag.json_init_args is not None:
@@ -303,7 +305,7 @@ def sanitize_html_id(html_id):
     return sanitized_html_id
 
 
-@contract(user=User, block=XBlock, view=basestring, frag=Fragment, context="dict|None")
+@contract(user=User, block=XBlock, view=six.string_types[0], frag=Fragment, context="dict|None")
 def add_staff_markup(user, disable_staff_debug_info, block, view, frag, context):  # pylint: disable=unused-argument
     """
     Updates the supplied module with a new get_html function that wraps