Moved sys.path-extending decorator to django.test.utils and used throughout test suite.

Thanks Aymeric for the suggestion.

django/test/utils.py

@@ -526,3 +526,15 @@ class TransRealMixin(object):
 requires_tz_support = skipUnless(TZ_SUPPORT,
         "This test relies on the ability to run a program in an arbitrary "
         "time zone, but your operating system isn't able to do that.")
+
+
+
+@contextmanager
+def extend_sys_path(*paths):
+    """Context manager to temporarily add paths to sys.path."""
+    _orig_sys_path = sys.path[:]
+    sys.path.extend(paths)
+    try:
+        yield
+    finally:
+        sys.path = _orig_sys_path

tests/app_loading/tests.py

 from __future__ import unicode_literals
 
 import os
-import sys
 
 from django.apps import apps
 from django.test import TestCase
+from django.test.utils import extend_sys_path
 from django.utils._os import upath
 from django.utils import six
 
@@ -12,17 +12,15 @@ from django.utils import six
 class EggLoadingTest(TestCase):
 
     def setUp(self):
-        self.old_path = sys.path[:]
         self.egg_dir = '%s/eggs' % os.path.dirname(upath(__file__))
 
     def tearDown(self):
         apps.clear_cache()
-        sys.path = self.old_path
 
     def test_egg1(self):
         """Models module can be loaded from an app in an egg"""
         egg_name = '%s/modelapp.egg' % self.egg_dir
-        sys.path.append(egg_name)
+        with extend_sys_path(egg_name):
             with self.settings(INSTALLED_APPS=['app_with_models']):
                 models_module = apps.get_app_config('app_with_models').models_module
                 self.assertIsNotNone(models_module)
@@ -31,7 +29,7 @@ class EggLoadingTest(TestCase):
     def test_egg2(self):
         """Loading an app from an egg that has no models returns no models (and no error)"""
         egg_name = '%s/nomodelapp.egg' % self.egg_dir
-        sys.path.append(egg_name)
+        with extend_sys_path(egg_name):
             with self.settings(INSTALLED_APPS=['app_no_models']):
                 models_module = apps.get_app_config('app_no_models').models_module
                 self.assertIsNone(models_module)
@@ -40,7 +38,7 @@ class EggLoadingTest(TestCase):
     def test_egg3(self):
         """Models module can be loaded from an app located under an egg's top-level package"""
         egg_name = '%s/omelet.egg' % self.egg_dir
-        sys.path.append(egg_name)
+        with extend_sys_path(egg_name):
             with self.settings(INSTALLED_APPS=['omelet.app_with_models']):
                 models_module = apps.get_app_config('app_with_models').models_module
                 self.assertIsNotNone(models_module)
@@ -49,7 +47,7 @@ class EggLoadingTest(TestCase):
     def test_egg4(self):
         """Loading an app with no models from under the top-level egg package generates no error"""
         egg_name = '%s/omelet.egg' % self.egg_dir
-        sys.path.append(egg_name)
+        with extend_sys_path(egg_name):
             with self.settings(INSTALLED_APPS=['omelet.app_no_models']):
                 models_module = apps.get_app_config('app_no_models').models_module
                 self.assertIsNone(models_module)
@@ -58,7 +56,7 @@ class EggLoadingTest(TestCase):
     def test_egg5(self):
         """Loading an app from an egg that has an import error in its models module raises that error"""
         egg_name = '%s/brokenapp.egg' % self.egg_dir
-        sys.path.append(egg_name)
+        with extend_sys_path(egg_name):
             with six.assertRaisesRegex(self, ImportError, 'modelz'):
                 with self.settings(INSTALLED_APPS=['broken_app']):
                     pass

tests/apps/tests.py

 from __future__ import absolute_import, unicode_literals
 
-from contextlib import contextmanager
 import os
 import sys
 from unittest import skipUnless
@@ -10,6 +9,7 @@ from django.apps.registry import Apps
 from django.core.exceptions import ImproperlyConfigured
 from django.db import models
 from django.test import TestCase, override_settings
+from django.test.utils import extend_sys_path
 from django.utils._os import upath
 from django.utils import six
 
@@ -189,21 +189,11 @@ class NamespacePackageAppTests(TestCase):
     other_location = os.path.join(HERE, 'namespace_package_other_base')
     app_path = os.path.join(base_location, 'nsapp')
 
-    @contextmanager
-    def add_to_path(self, *paths):
-        """Context manager to temporarily add paths to sys.path."""
-        _orig_sys_path = sys.path[:]
-        sys.path.extend(paths)
-        try:
-            yield
-        finally:
-            sys.path = _orig_sys_path
-
     def test_single_path(self):
         """
         A Py3.3+ namespace package can be an app if it has only one path.
         """
-        with self.add_to_path(self.base_location):
+        with extend_sys_path(self.base_location):
             with self.settings(INSTALLED_APPS=['nsapp']):
                 app_config = apps.get_app_config('nsapp')
                 self.assertEqual(app_config.path, upath(self.app_path))
@@ -218,7 +208,7 @@ class NamespacePackageAppTests(TestCase):
         """
         # Temporarily add two directories to sys.path that both contain
         # components of the "nsapp" package.
-        with self.add_to_path(self.base_location, self.other_location):
+        with extend_sys_path(self.base_location, self.other_location):
             with self.assertRaises(ImproperlyConfigured):
                 with self.settings(INSTALLED_APPS=['nsapp']):
                     pass
@@ -229,7 +219,7 @@ class NamespacePackageAppTests(TestCase):
         """
         # Temporarily add two directories to sys.path that both contain
         # components of the "nsapp" package.
-        with self.add_to_path(self.base_location, self.other_location):
+        with extend_sys_path(self.base_location, self.other_location):
             with self.settings(INSTALLED_APPS=['nsapp.apps.NSAppConfig']):
                 app_config = apps.get_app_config('nsapp')
                 self.assertEqual(app_config.path, upath(self.app_path))

tests/proxy_model_inheritance/tests.py

 from __future__ import absolute_import, unicode_literals
 
 import os
-import sys
 
 from django.core.management import call_command
 from django.test import TestCase, TransactionTestCase
-from django.test.utils import override_system_checks
+from django.test.utils import override_system_checks, extend_sys_path
 from django.utils._os import upath
 
 from .models import (ConcreteModel, ConcreteModelSubclass,
@@ -20,17 +19,11 @@ class ProxyModelInheritanceTests(TransactionTestCase):
     """
     available_apps = []
 
-    def setUp(self):
-        self.old_sys_path = sys.path[:]
-        sys.path.append(os.path.dirname(os.path.abspath(upath(__file__))))
-
-    def tearDown(self):
-        sys.path = self.old_sys_path
-
     # `auth` app is imported, but not installed in this test, so we need to
     # exclude checks registered by this app.
     @override_system_checks([])
     def test_table_exists(self):
+        with extend_sys_path(os.path.dirname(os.path.abspath(upath(__file__)))):
             with self.modify_settings(INSTALLED_APPS={'append': ['app1', 'app2']}):
                 call_command('migrate', verbosity=0)
                 from app1.models import ProxyModel

tests/template_tests/tests.py

@@ -22,7 +22,8 @@ from django.template import (base as template_base, loader, Context,
 from django.template.loaders import app_directories, filesystem, cached
 from django.test import RequestFactory, TestCase
 from django.test.utils import (setup_test_template_loader,
-    restore_template_loaders, override_settings, TransRealMixin)
+    restore_template_loaders, override_settings, TransRealMixin,
+    extend_sys_path)
 from django.utils.encoding import python_2_unicode_compatible
 from django.utils.formats import date_format
 from django.utils._os import upath
@@ -1857,13 +1858,11 @@ class TemplateTests(TransRealMixin, TestCase):
 class TemplateTagLoading(TestCase):
 
     def setUp(self):
-        self.old_path = sys.path[:]
         self.egg_dir = '%s/eggs' % os.path.dirname(upath(__file__))
         self.old_tag_modules = template_base.templatetags_modules
         template_base.templatetags_modules = []
 
     def tearDown(self):
-        sys.path = self.old_path
         template_base.templatetags_modules = self.old_tag_modules
 
     def test_load_error(self):
@@ -1878,7 +1877,7 @@ class TemplateTagLoading(TestCase):
     def test_load_error_egg(self):
         ttext = "{% load broken_egg %}"
         egg_name = '%s/tagsegg.egg' % self.egg_dir
-        sys.path.append(egg_name)
+        with extend_sys_path(egg_name):
             with self.assertRaises(template.TemplateSyntaxError):
                 with self.settings(INSTALLED_APPS=['tagsegg']):
                     template.Template(ttext)
@@ -1892,7 +1891,7 @@ class TemplateTagLoading(TestCase):
     def test_load_working_egg(self):
         ttext = "{% load working_egg %}"
         egg_name = '%s/tagsegg.egg' % self.egg_dir
-        sys.path.append(egg_name)
+        with extend_sys_path(egg_name):
             with self.settings(INSTALLED_APPS=['tagsegg']):
                 template.Template(ttext)
 

tests/utils_tests/test_module_loading.py

@@ -7,6 +7,7 @@ from zipimport import zipimporter
 
 from django.core.exceptions import ImproperlyConfigured
 from django.test import SimpleTestCase, modify_settings
+from django.test.utils import extend_sys_path
 from django.utils import six
 from django.utils.module_loading import autodiscover_modules, import_by_path, module_has_submodule
 from django.utils._os import upath
@@ -54,11 +55,9 @@ class DefaultLoader(unittest.TestCase):
 
 class EggLoader(unittest.TestCase):
     def setUp(self):
-        self.old_path = sys.path[:]
         self.egg_dir = '%s/eggs' % os.path.dirname(upath(__file__))
 
     def tearDown(self):
-        sys.path = self.old_path
         sys.path_importer_cache.clear()
 
         sys.modules.pop('egg_module.sub1.sub2.bad_module', None)
@@ -72,7 +71,7 @@ class EggLoader(unittest.TestCase):
     def test_shallow_loader(self):
         "Module existence can be tested inside eggs"
         egg_name = '%s/test_egg.egg' % self.egg_dir
-        sys.path.append(egg_name)
+        with extend_sys_path(egg_name):
             egg_module = import_module('egg_module')
 
             # An importable child
@@ -91,7 +90,7 @@ class EggLoader(unittest.TestCase):
     def test_deep_loader(self):
         "Modules deep inside an egg can still be tested for existence"
         egg_name = '%s/test_egg.egg' % self.egg_dir
-        sys.path.append(egg_name)
+        with extend_sys_path(egg_name):
             egg_module = import_module('egg_module.sub1.sub2')
 
             # An importable child