Refs #27804 -- Used subTest() in several tests.

19 files changed, 324 insertions, 262 deletions

diff --git a/tests/admin_docs/test_views.py b/tests/admin_docs/test_views.py
index 0915e01dc4..b9955717f4 100644
--- a/tests/admin_docs/test_views.py
+++ b/tests/admin_docs/test_views.py
@@ -339,4 +339,5 @@ class AdminDocViewFunctionsTests(SimpleTestCase):
             (r'^a/?$', '/a/'),
         )
         for pattern, output in tests:
-            self.assertEqual(simplify_regex(pattern), output)
+            with self.subTest(pattern=pattern):
+                self.assertEqual(simplify_regex(pattern), output)
diff --git a/tests/admin_views/test_multidb.py b/tests/admin_views/test_multidb.py
index 3687bec16f..9907e16d69 100644
--- a/tests/admin_views/test_multidb.py
+++ b/tests/admin_views/test_multidb.py
@@ -47,32 +47,35 @@ class MultiDatabaseTests(TestCase):
     @mock.patch('django.contrib.admin.options.transaction')
     def test_add_view(self, mock):
         for db in connections:
-            Router.target_db = db
-            self.client.force_login(self.superusers[db])
-            self.client.post(
-                reverse('test_adminsite:admin_views_book_add'),
-                {'name': 'Foobar: 5th edition'},
-            )
-            mock.atomic.assert_called_with(using=db)
+            with self.subTest(db=db):
+                Router.target_db = db
+                self.client.force_login(self.superusers[db])
+                self.client.post(
+                    reverse('test_adminsite:admin_views_book_add'),
+                    {'name': 'Foobar: 5th edition'},
+                )
+                mock.atomic.assert_called_with(using=db)
 
     @mock.patch('django.contrib.admin.options.transaction')
     def test_change_view(self, mock):
         for db in connections:
-            Router.target_db = db
-            self.client.force_login(self.superusers[db])
-            self.client.post(
-                reverse('test_adminsite:admin_views_book_change', args=[self.test_book_ids[db]]),
-                {'name': 'Test Book 2: Test more'},
-            )
-            mock.atomic.assert_called_with(using=db)
+            with self.subTest(db=db):
+                Router.target_db = db
+                self.client.force_login(self.superusers[db])
+                self.client.post(
+                    reverse('test_adminsite:admin_views_book_change', args=[self.test_book_ids[db]]),
+                    {'name': 'Test Book 2: Test more'},
+                )
+                mock.atomic.assert_called_with(using=db)
 
     @mock.patch('django.contrib.admin.options.transaction')
     def test_delete_view(self, mock):
         for db in connections:
-            Router.target_db = db
-            self.client.force_login(self.superusers[db])
-            self.client.post(
-                reverse('test_adminsite:admin_views_book_delete', args=[self.test_book_ids[db]]),
-                {'post': 'yes'},
-            )
-            mock.atomic.assert_called_with(using=db)
+            with self.subTest(db=db):
+                Router.target_db = db
+                self.client.force_login(self.superusers[db])
+                self.client.post(
+                    reverse('test_adminsite:admin_views_book_delete', args=[self.test_book_ids[db]]),
+                    {'post': 'yes'},
+                )
+                mock.atomic.assert_called_with(using=db)
diff --git a/tests/auth_tests/test_admin_multidb.py b/tests/auth_tests/test_admin_multidb.py
index 6b36b50a16..f86ea86dd8 100644
--- a/tests/auth_tests/test_admin_multidb.py
+++ b/tests/auth_tests/test_admin_multidb.py
@@ -42,11 +42,12 @@ class MultiDatabaseTests(TestCase):
     @mock.patch('django.contrib.auth.admin.transaction')
     def test_add_view(self, mock):
         for db in connections:
-            Router.target_db = db
-            self.client.force_login(self.superusers[db])
-            self.client.post(reverse('test_adminsite:auth_user_add'), {
-                'username': 'some_user',
-                'password1': 'helloworld',
-                'password2': 'helloworld',
-            })
-            mock.atomic.assert_called_with(using=db)
+            with self.subTest(db_connection=db):
+                Router.target_db = db
+                self.client.force_login(self.superusers[db])
+                self.client.post(reverse('test_adminsite:auth_user_add'), {
+                    'username': 'some_user',
+                    'password1': 'helloworld',
+                    'password2': 'helloworld',
+                })
+                mock.atomic.assert_called_with(using=db)
diff --git a/tests/auth_tests/test_hashers.py b/tests/auth_tests/test_hashers.py
index aec7021cab..cf12fd4168 100644
--- a/tests/auth_tests/test_hashers.py
+++ b/tests/auth_tests/test_hashers.py
@@ -300,13 +300,14 @@ class TestUtilsHashPass(SimpleTestCase):
     def test_upgrade(self):
         self.assertEqual('pbkdf2_sha256', get_hasher('default').algorithm)
         for algo in ('sha1', 'md5'):
-            encoded = make_password('lètmein', hasher=algo)
-            state = {'upgraded': False}
+            with self.subTest(algo=algo):
+                encoded = make_password('lètmein', hasher=algo)
+                state = {'upgraded': False}
 
-            def setter(password):
-                state['upgraded'] = True
-            self.assertTrue(check_password('lètmein', encoded, setter))
-            self.assertTrue(state['upgraded'])
+                def setter(password):
+                    state['upgraded'] = True
+                self.assertTrue(check_password('lètmein', encoded, setter))
+                self.assertTrue(state['upgraded'])
 
     def test_no_upgrade(self):
         encoded = make_password('lètmein')
@@ -327,13 +328,14 @@ class TestUtilsHashPass(SimpleTestCase):
     def test_no_upgrade_on_incorrect_pass(self):
         self.assertEqual('pbkdf2_sha256', get_hasher('default').algorithm)
         for algo in ('sha1', 'md5'):
-            encoded = make_password('lètmein', hasher=algo)
-            state = {'upgraded': False}
+            with self.subTest(algo=algo):
+                encoded = make_password('lètmein', hasher=algo)
+                state = {'upgraded': False}
 
-            def setter():
-                state['upgraded'] = True
-            self.assertFalse(check_password('WRONG', encoded, setter))
-            self.assertFalse(state['upgraded'])
+                def setter():
+                    state['upgraded'] = True
+                self.assertFalse(check_password('WRONG', encoded, setter))
+                self.assertFalse(state['upgraded'])
 
     def test_pbkdf2_upgrade(self):
         hasher = get_hasher('default')
diff --git a/tests/auth_tests/test_models.py b/tests/auth_tests/test_models.py
index 142fbcc39c..e546d61c64 100644
--- a/tests/auth_tests/test_models.py
+++ b/tests/auth_tests/test_models.py
@@ -161,7 +161,7 @@ class AbstractBaseUserTests(TestCase):
         # The normalization happens in AbstractBaseUser.clean()
         ohm_username = 'iamtheΩ'  # U+2126 OHM SIGN
         for model in ('auth.User', 'auth_tests.CustomUser'):
-            with self.settings(AUTH_USER_MODEL=model):
+            with self.subTest(model=model), self.settings(AUTH_USER_MODEL=model):
                 User = get_user_model()
                 user = User(**{User.USERNAME_FIELD: ohm_username, 'password': 'foo'})
                 user.clean()
diff --git a/tests/auth_tests/test_validators.py b/tests/auth_tests/test_validators.py
index e9dc1f7f3f..068dec9981 100644
--- a/tests/auth_tests/test_validators.py
+++ b/tests/auth_tests/test_validators.py
@@ -214,17 +214,21 @@ class UsernameValidatorsTests(TestCase):
         ]
         v = validators.UnicodeUsernameValidator()
         for valid in valid_usernames:
-            v(valid)
+            with self.subTest(valid=valid):
+                v(valid)
         for invalid in invalid_usernames:
-            with self.assertRaises(ValidationError):
-                v(invalid)
+            with self.subTest(invalid=invalid):
+                with self.assertRaises(ValidationError):
+                    v(invalid)
 
     def test_ascii_validator(self):
         valid_usernames = ['glenn', 'GLEnN', 'jean-marc']
         invalid_usernames = ["o'connell", 'Éric', 'jean marc', "أحمد"]
         v = validators.ASCIIUsernameValidator()
         for valid in valid_usernames:
-            v(valid)
+            with self.subTest(valid=valid):
+                v(valid)
         for invalid in invalid_usernames:
-            with self.assertRaises(ValidationError):
-                v(invalid)
+            with self.subTest(invalid=invalid):
+                with self.assertRaises(ValidationError):
+                    v(invalid)
diff --git a/tests/auth_tests/test_views.py b/tests/auth_tests/test_views.py
index 40c48b7e9e..7dbf74928d 100644
--- a/tests/auth_tests/test_views.py
+++ b/tests/auth_tests/test_views.py
@@ -108,10 +108,11 @@ class AuthViewNamedURLTests(AuthViewsTestCase):
             ('password_reset_complete', [], {}),
         ]
         for name, args, kwargs in expected_named_urls:
-            try:
-                reverse(name, args=args, kwargs=kwargs)
-            except NoReverseMatch:
-                self.fail("Reversal of url named '%s' failed with NoReverseMatch" % name)
+            with self.subTest(name=name):
+                try:
+                    reverse(name, args=args, kwargs=kwargs)
+                except NoReverseMatch:
+                    self.fail("Reversal of url named '%s' failed with NoReverseMatch" % name)
 
 
 class PasswordResetTest(AuthViewsTestCase):
@@ -559,48 +560,54 @@ class LoginTest(AuthViewsTestCase):
     def test_security_check(self):
         login_url = reverse('login')
 
-        # Those URLs should not pass the security check
-        for bad_url in ('http://example.com',
-                        'http:///example.com',
-                        'https://example.com',
-                        'ftp://example.com',
-                        '///example.com',
-                        '//example.com',
-                        'javascript:alert("XSS")'):
-
-            nasty_url = '%(url)s?%(next)s=%(bad_url)s' % {
-                'url': login_url,
-                'next': REDIRECT_FIELD_NAME,
-                'bad_url': quote(bad_url),
-            }
-            response = self.client.post(nasty_url, {
-                'username': 'testclient',
-                'password': 'password',
-            })
-            self.assertEqual(response.status_code, 302)
-            self.assertNotIn(bad_url, response.url,
-                             "%s should be blocked" % bad_url)
+        # These URLs should not pass the security check.
+        bad_urls = (
+            'http://example.com',
+            'http:///example.com',
+            'https://example.com',
+            'ftp://example.com',
+            '///example.com',
+            '//example.com',
+            'javascript:alert("XSS")',
+        )
+        for bad_url in bad_urls:
+            with self.subTest(bad_url=bad_url):
+                nasty_url = '%(url)s?%(next)s=%(bad_url)s' % {
+                    'url': login_url,
+                    'next': REDIRECT_FIELD_NAME,
+                    'bad_url': quote(bad_url),
+                }
+                response = self.client.post(nasty_url, {
+                    'username': 'testclient',
+                    'password': 'password',
+                })
+                self.assertEqual(response.status_code, 302)
+                self.assertNotIn(bad_url, response.url, '%s should be blocked' % bad_url)
 
-        # These URLs *should* still pass the security check
-        for good_url in ('/view/?param=http://example.com',
-                         '/view/?param=https://example.com',
-                         '/view?param=ftp://example.com',
-                         'view/?param=//example.com',
-                         'https://testserver/',
-                         'HTTPS://testserver/',
-                         '//testserver/',
-                         '/url%20with%20spaces/'):  # see ticket #12534
-            safe_url = '%(url)s?%(next)s=%(good_url)s' % {
-                'url': login_url,
-                'next': REDIRECT_FIELD_NAME,
-                'good_url': quote(good_url),
-            }
-            response = self.client.post(safe_url, {
-                'username': 'testclient',
-                'password': 'password',
-            })
-            self.assertEqual(response.status_code, 302)
-            self.assertIn(good_url, response.url, "%s should be allowed" % good_url)
+        # These URLs should pass the security check.
+        good_urls = (
+            '/view/?param=http://example.com',
+            '/view/?param=https://example.com',
+            '/view?param=ftp://example.com',
+            'view/?param=//example.com',
+            'https://testserver/',
+            'HTTPS://testserver/',
+            '//testserver/',
+            '/url%20with%20spaces/',
+        )
+        for good_url in good_urls:
+            with self.subTest(good_url=good_url):
+                safe_url = '%(url)s?%(next)s=%(good_url)s' % {
+                    'url': login_url,
+                    'next': REDIRECT_FIELD_NAME,
+                    'good_url': quote(good_url),
+                }
+                response = self.client.post(safe_url, {
+                    'username': 'testclient',
+                    'password': 'password',
+                })
+                self.assertEqual(response.status_code, 302)
+                self.assertIn(good_url, response.url, '%s should be allowed' % good_url)
 
     def test_security_check_https(self):
         login_url = reverse('login')
@@ -988,45 +995,52 @@ class LogoutTest(AuthViewsTestCase):
     def test_security_check(self):
         logout_url = reverse('logout')
 
-        # Those URLs should not pass the security check
-        for bad_url in ('http://example.com',
-                        'http:///example.com',
-                        'https://example.com',
-                        'ftp://example.com',
-                        '///example.com',
-                        '//example.com',
-                        'javascript:alert("XSS")'):
-            nasty_url = '%(url)s?%(next)s=%(bad_url)s' % {
-                'url': logout_url,
-                'next': REDIRECT_FIELD_NAME,
-                'bad_url': quote(bad_url),
-            }
-            self.login()
-            response = self.client.get(nasty_url)
-            self.assertEqual(response.status_code, 302)
-            self.assertNotIn(bad_url, response.url,
-                             "%s should be blocked" % bad_url)
-            self.confirm_logged_out()
+        # These URLs should not pass the security check.
+        bad_urls = (
+            'http://example.com',
+            'http:///example.com',
+            'https://example.com',
+            'ftp://example.com',
+            '///example.com',
+            '//example.com',
+            'javascript:alert("XSS")',
+        )
+        for bad_url in bad_urls:
+            with self.subTest(bad_url=bad_url):
+                nasty_url = '%(url)s?%(next)s=%(bad_url)s' % {
+                    'url': logout_url,
+                    'next': REDIRECT_FIELD_NAME,
+                    'bad_url': quote(bad_url),
+                }
+                self.login()
+                response = self.client.get(nasty_url)
+                self.assertEqual(response.status_code, 302)
+                self.assertNotIn(bad_url, response.url, '%s should be blocked' % bad_url)
+                self.confirm_logged_out()
 
-        # These URLs *should* still pass the security check
-        for good_url in ('/view/?param=http://example.com',
-                         '/view/?param=https://example.com',
-                         '/view?param=ftp://example.com',
-                         'view/?param=//example.com',
-                         'https://testserver/',
-                         'HTTPS://testserver/',
-                         '//testserver/',
-                         '/url%20with%20spaces/'):  # see ticket #12534
-            safe_url = '%(url)s?%(next)s=%(good_url)s' % {
-                'url': logout_url,
-                'next': REDIRECT_FIELD_NAME,
-                'good_url': quote(good_url),
-            }
-            self.login()
-            response = self.client.get(safe_url)
-            self.assertEqual(response.status_code, 302)
-            self.assertIn(good_url, response.url, "%s should be allowed" % good_url)
-            self.confirm_logged_out()
+        # These URLs should pass the security check.
+        good_urls = (
+            '/view/?param=http://example.com',
+            '/view/?param=https://example.com',
+            '/view?param=ftp://example.com',
+            'view/?param=//example.com',
+            'https://testserver/',
+            'HTTPS://testserver/',
+            '//testserver/',
+            '/url%20with%20spaces/',
+        )
+        for good_url in good_urls:
+            with self.subTest(good_url=good_url):
+                safe_url = '%(url)s?%(next)s=%(good_url)s' % {
+                    'url': logout_url,
+                    'next': REDIRECT_FIELD_NAME,
+                    'good_url': quote(good_url),
+                }
+                self.login()
+                response = self.client.get(safe_url)
+                self.assertEqual(response.status_code, 302)
+                self.assertIn(good_url, response.url, '%s should be allowed' % good_url)
+                self.confirm_logged_out()
 
     def test_security_check_https(self):
         logout_url = reverse('logout')
diff --git a/tests/cache/tests.py b/tests/cache/tests.py
index 203f2f5152..e14c72754d 100644
--- a/tests/cache/tests.py
+++ b/tests/cache/tests.py
@@ -169,8 +169,9 @@ class DummyCacheTests(SimpleTestCase):
             'ascii2': {'x': 1}
         }
         for (key, value) in stuff.items():
-            cache.set(key, value)
-            self.assertIsNone(cache.get(key))
+            with self.subTest(key=key):
+                cache.set(key, value)
+                self.assertIsNone(cache.get(key))
 
     def test_set_many(self):
         "set_many does nothing for the dummy cache backend"
@@ -420,21 +421,24 @@ class BaseCacheTests:
         }
         # Test `set`
         for (key, value) in stuff.items():
-            cache.set(key, value)
-            self.assertEqual(cache.get(key), value)
+            with self.subTest(key=key):
+                cache.set(key, value)
+                self.assertEqual(cache.get(key), value)
 
         # Test `add`
         for (key, value) in stuff.items():
-            cache.delete(key)
-            cache.add(key, value)
-            self.assertEqual(cache.get(key), value)
+            with self.subTest(key=key):
+                cache.delete(key)
+                cache.add(key, value)
+                self.assertEqual(cache.get(key), value)
 
         # Test `set_many`
         for (key, value) in stuff.items():
             cache.delete(key)
         cache.set_many(stuff)
         for (key, value) in stuff.items():
-            self.assertEqual(cache.get(key), value)
+            with self.subTest(key=key):
+                self.assertEqual(cache.get(key), value)
 
     def test_binary_string(self):
         # Binary strings should be cacheable
@@ -1151,9 +1155,10 @@ class BaseMemcachedTests(BaseCacheTests):
             'server1.tld,server2:11211',
         ]
         for location in locations:
-            params = {'BACKEND': self.base_params['BACKEND'], 'LOCATION': location}
-            with self.settings(CACHES={'default': params}):
-                self.assertEqual(cache._servers, ['server1.tld', 'server2:11211'])
+            with self.subTest(location=location):
+                params = {'BACKEND': self.base_params['BACKEND'], 'LOCATION': location}
+                with self.settings(CACHES={'default': params}):
+                    self.assertEqual(cache._servers, ['server1.tld', 'server2:11211'])
 
     def test_invalid_key_characters(self):
         """
@@ -1250,7 +1255,8 @@ class MemcachedCacheTests(BaseMemcachedTests, TestCase):
     def test_memcached_uses_highest_pickle_version(self):
         # Regression test for #19810
         for cache_key in settings.CACHES:
-            self.assertEqual(caches[cache_key]._cache.pickleProtocol, pickle.HIGHEST_PROTOCOL)
+            with self.subTest(cache_key=cache_key):
+                self.assertEqual(caches[cache_key]._cache.pickleProtocol, pickle.HIGHEST_PROTOCOL)
 
     @override_settings(CACHES=caches_setting_for_tests(
         base=MemcachedCache_params,
@@ -1521,11 +1527,12 @@ class CacheUtils(SimpleTestCase):
             ('Cookie    ,     Accept-Encoding', ('Accept-Encoding', 'cookie'), 'Cookie, Accept-Encoding'),
         )
         for initial_vary, newheaders, resulting_vary in headers:
-            response = HttpResponse()
-            if initial_vary is not None:
-                response['Vary'] = initial_vary
-            patch_vary_headers(response, newheaders)
-            self.assertEqual(response['Vary'], resulting_vary)
+            with self.subTest(initial_vary=initial_vary, newheaders=newheaders):
+                response = HttpResponse()
+                if initial_vary is not None:
+                    response['Vary'] = initial_vary
+                patch_vary_headers(response, newheaders)
+                self.assertEqual(response['Vary'], resulting_vary)
 
     def test_get_cache_key(self):
         request = self.factory.get(self.path)
@@ -1605,12 +1612,13 @@ class CacheUtils(SimpleTestCase):
         cc_delim_re = re.compile(r'\s*,\s*')
 
         for initial_cc, newheaders, expected_cc in tests:
-            response = HttpResponse()
-            if initial_cc is not None:
-                response['Cache-Control'] = initial_cc
-            patch_cache_control(response, **newheaders)
-            parts = set(cc_delim_re.split(response['Cache-Control']))
-            self.assertEqual(parts, expected_cc)
+            with self.subTest(initial_cc=initial_cc, newheaders=newheaders):
+                response = HttpResponse()
+                if initial_cc is not None:
+                    response['Cache-Control'] = initial_cc
+                patch_cache_control(response, **newheaders)
+                parts = set(cc_delim_re.split(response['Cache-Control']))
+                self.assertEqual(parts, expected_cc)
 
 
 @override_settings(
@@ -2179,12 +2187,13 @@ class TestWithTemplateResponse(SimpleTestCase):
             ('Cookie    ,     Accept-Encoding', ('Accept-Encoding', 'cookie'), 'Cookie, Accept-Encoding'),
         )
         for initial_vary, newheaders, resulting_vary in headers:
-            template = engines['django'].from_string("This is a test")
-            response = TemplateResponse(HttpRequest(), template)
-            if initial_vary is not None:
-                response['Vary'] = initial_vary
-            patch_vary_headers(response, newheaders)
-            self.assertEqual(response['Vary'], resulting_vary)
+            with self.subTest(initial_vary=initial_vary, newheaders=newheaders):
+                template = engines['django'].from_string("This is a test")
+                response = TemplateResponse(HttpRequest(), template)
+                if initial_vary is not None:
+                    response['Vary'] = initial_vary
+                patch_vary_headers(response, newheaders)
+                self.assertEqual(response['Vary'], resulting_vary)
 
     def test_get_cache_key(self):
         request = self.factory.get(self.path)
diff --git a/tests/contenttypes_tests/test_views.py b/tests/contenttypes_tests/test_views.py
index d1165c6818..cdfa1e0961 100644
--- a/tests/contenttypes_tests/test_views.py
+++ b/tests/contenttypes_tests/test_views.py
@@ -45,9 +45,10 @@ class ContentTypesViewsTests(TestCase):
     def test_shortcut_with_absolute_url(self):
         "Can view a shortcut for an Author object that has a get_absolute_url method"
         for obj in Author.objects.all():
-            short_url = '/shortcut/%s/%s/' % (ContentType.objects.get_for_model(Author).id, obj.pk)
-            response = self.client.get(short_url)
-            self.assertRedirects(response, 'http://testserver%s' % obj.get_absolute_url(), target_status_code=404)
+            with self.subTest(obj=obj):
+                short_url = '/shortcut/%s/%s/' % (ContentType.objects.get_for_model(Author).id, obj.pk)
+                response = self.client.get(short_url)
+                self.assertRedirects(response, 'http://testserver%s' % obj.get_absolute_url(), target_status_code=404)
 
     def test_shortcut_with_absolute_url_including_scheme(self):
         """
@@ -55,9 +56,10 @@ class ContentTypesViewsTests(TestCase):
         the tested URLs are: "http://...", "https://..." and "//..."
         """
         for obj in SchemeIncludedURL.objects.all():
-            short_url = '/shortcut/%s/%s/' % (ContentType.objects.get_for_model(SchemeIncludedURL).id, obj.pk)
-            response = self.client.get(short_url)
-            self.assertRedirects(response, obj.get_absolute_url(), fetch_redirect_response=False)
+            with self.subTest(obj=obj):
+                short_url = '/shortcut/%s/%s/' % (ContentType.objects.get_for_model(SchemeIncludedURL).id, obj.pk)
+                response = self.client.get(short_url)
+                self.assertRedirects(response, obj.get_absolute_url(), fetch_redirect_response=False)
 
     def test_shortcut_no_absolute_url(self):
         """
@@ -65,9 +67,10 @@ class ContentTypesViewsTests(TestCase):
         404.
         """
         for obj in Article.objects.all():
-            short_url = '/shortcut/%s/%s/' % (ContentType.objects.get_for_model(Article).id, obj.pk)
-            response = self.client.get(short_url)
-            self.assertEqual(response.status_code, 404)
+            with self.subTest(obj=obj):
+                short_url = '/shortcut/%s/%s/' % (ContentType.objects.get_for_model(Article).id, obj.pk)
+                response = self.client.get(short_url)
+                self.assertEqual(response.status_code, 404)
 
     def test_wrong_type_pk(self):
         short_url = '/shortcut/%s/%s/' % (ContentType.objects.get_for_model(Author).id, 'nobody/expects')
diff --git a/tests/custom_managers/tests.py b/tests/custom_managers/tests.py
index 54f3b58a79..d095036f10 100644
--- a/tests/custom_managers/tests.py
+++ b/tests/custom_managers/tests.py
@@ -42,41 +42,44 @@ class CustomManagerTests(TestCase):
         default Manager.
         """
         for manager_name in self.custom_manager_names:
-            manager = getattr(Person, manager_name)
+            with self.subTest(manager_name=manager_name):
+                manager = getattr(Person, manager_name)
 
-            # Public methods are copied
-            manager.public_method()
-            # Private methods are not copied
-            with self.assertRaises(AttributeError):
-                manager._private_method()
+                # Public methods are copied
+                manager.public_method()
+                # Private methods are not copied
+                with self.assertRaises(AttributeError):
+                    manager._private_method()
 
     def test_manager_honors_queryset_only(self):
         for manager_name in self.custom_manager_names:
-            manager = getattr(Person, manager_name)
-            # Methods with queryset_only=False are copied even if they are private.
-            manager._optin_private_method()
-            # Methods with queryset_only=True aren't copied even if they are public.
-            with self.assertRaises(AttributeError):
-                manager.optout_public_method()
+            with self.subTest(manager_name=manager_name):
+                manager = getattr(Person, manager_name)
+                # Methods with queryset_only=False are copied even if they are private.
+                manager._optin_private_method()
+                # Methods with queryset_only=True aren't copied even if they are public.
+                with self.assertRaises(AttributeError):
+                    manager.optout_public_method()
 
     def test_manager_use_queryset_methods(self):
         """
         Custom manager will use the queryset methods
         """
         for manager_name in self.custom_manager_names:
-            manager = getattr(Person, manager_name)
-            queryset = manager.filter()
-            self.assertQuerysetEqual(queryset, ["Bugs Bunny"], str)
-            self.assertIs(queryset._filter_CustomQuerySet, True)
+            with self.subTest(manager_name=manager_name):
+                manager = getattr(Person, manager_name)
+                queryset = manager.filter()
+                self.assertQuerysetEqual(queryset, ["Bugs Bunny"], str)
+                self.assertIs(queryset._filter_CustomQuerySet, True)
 
-            # Specialized querysets inherit from our custom queryset.
-            queryset = manager.values_list('first_name', flat=True).filter()
-            self.assertEqual(list(queryset), ["Bugs"])
-            self.assertIs(queryset._filter_CustomQuerySet, True)
+                # Specialized querysets inherit from our custom queryset.
+                queryset = manager.values_list('first_name', flat=True).filter()
+                self.assertEqual(list(queryset), ["Bugs"])
+                self.assertIs(queryset._filter_CustomQuerySet, True)
 
-            self.assertIsInstance(queryset.values(), CustomQuerySet)
-            self.assertIsInstance(queryset.values().values(), CustomQuerySet)
-            self.assertIsInstance(queryset.values_list().values(), CustomQuerySet)
+                self.assertIsInstance(queryset.values(), CustomQuerySet)
+                self.assertIsInstance(queryset.values().values(), CustomQuerySet)
+                self.assertIsInstance(queryset.values_list().values(), CustomQuerySet)
 
     def test_init_args(self):
         """
diff --git a/tests/db_typecasts/tests.py b/tests/db_typecasts/tests.py
index 56d37c112d..4d65ca8d4d 100644
--- a/tests/db_typecasts/tests.py
+++ b/tests/db_typecasts/tests.py
@@ -54,9 +54,9 @@ class DBTypeCasts(unittest.TestCase):
     def test_typeCasts(self):
         for k, v in TEST_CASES.items():
             for inpt, expected in v:
-                got = getattr(typecasts, k)(inpt)
-                self.assertEqual(
-                    got,
-                    expected,
-                    "In %s: %r doesn't match %r. Got %r instead." % (k, inpt, expected, got)
-                )
+                with self.subTest(k=k, inpt=inpt):
+                    got = getattr(typecasts, k)(inpt)
+                    self.assertEqual(
+                        got, expected,
+                        "In %s: %r doesn't match %r. Got %r instead." % (k, inpt, expected, got)
+                    )
diff --git a/tests/forms_tests/field_tests/test_filepathfield.py b/tests/forms_tests/field_tests/test_filepathfield.py
index cbdf97b4c2..56bf0e9fda 100644
--- a/tests/forms_tests/field_tests/test_filepathfield.py
+++ b/tests/forms_tests/field_tests/test_filepathfield.py
@@ -38,8 +38,9 @@ class FilePathFieldTest(SimpleTestCase):
             ('/django/forms/widgets.py', 'widgets.py')
         ]
         for exp, got in zip(expected, fix_os_paths(f.choices)):
-            self.assertEqual(exp[1], got[1])
-            self.assertTrue(got[0].endswith(exp[0]))
+            with self.subTest(expected=exp):
+                self.assertEqual(exp[1], got[1])
+                self.assertTrue(got[0].endswith(exp[0]))
         msg = "'Select a valid choice. fields.py is not one of the available choices.'"
         with self.assertRaisesMessage(ValidationError, msg):
             f.clean('fields.py')
@@ -61,8 +62,9 @@ class FilePathFieldTest(SimpleTestCase):
             ('/django/forms/widgets.py', 'widgets.py')
         ]
         for exp, got in zip(expected, fix_os_paths(f.choices)):
-            self.assertEqual(exp[1], got[1])
-            self.assertTrue(got[0].endswith(exp[0]))
+            with self.subTest(expected=exp):
+                self.assertEqual(exp[1], got[1])
+                self.assertTrue(got[0].endswith(exp[0]))
 
     def test_filepathfield_4(self):
         path = os.path.dirname(os.path.abspath(forms.__file__)) + '/'
@@ -80,8 +82,9 @@ class FilePathFieldTest(SimpleTestCase):
             ('/django/forms/widgets.py', 'widgets.py')
         ]
         for exp, got in zip(expected, fix_os_paths(f.choices)):
-            self.assertEqual(exp[1], got[1])
-            self.assertTrue(got[0].endswith(exp[0]))
+            with self.subTest(expected=exp):
+                self.assertEqual(exp[1], got[1])
+                self.assertTrue(got[0].endswith(exp[0]))
 
     def test_filepathfield_folders(self):
         path = os.path.abspath(os.path.join(__file__, '..', '..')) + '/tests/filepath_test_files/'
@@ -93,8 +96,9 @@ class FilePathFieldTest(SimpleTestCase):
         actual = fix_os_paths(f.choices)
         self.assertEqual(len(expected), len(actual))
         for exp, got in zip(expected, actual):
-            self.assertEqual(exp[1], got[1])
-            self.assertTrue(got[0].endswith(exp[0]))
+            with self.subTest(expected=exp):
+                self.assertEqual(exp[1], got[1])
+                self.assertTrue(got[0].endswith(exp[0]))
 
         f = FilePathField(path=path, allow_folders=True, allow_files=True)
         f.choices.sort()
@@ -110,5 +114,6 @@ class FilePathFieldTest(SimpleTestCase):
         actual = fix_os_paths(f.choices)
         self.assertEqual(len(expected), len(actual))
         for exp, got in zip(expected, actual):
-            self.assertEqual(exp[1], got[1])
-            self.assertTrue(got[0].endswith(exp[0]))
+            with self.subTest(expected=exp):
+                self.assertEqual(exp[1], got[1])
+                self.assertTrue(got[0].endswith(exp[0]))
diff --git a/tests/forms_tests/field_tests/test_urlfield.py b/tests/forms_tests/field_tests/test_urlfield.py
index 715e8e99e0..2ecf189112 100644
--- a/tests/forms_tests/field_tests/test_urlfield.py
+++ b/tests/forms_tests/field_tests/test_urlfield.py
@@ -127,8 +127,9 @@ class URLFieldTest(FormFieldAssertionsMixin, SimpleTestCase):
             'http://العربية.idn.icann.org/',
         )
         for url in urls:
-            # Valid IDN
-            self.assertEqual(url, f.clean(url))
+            with self.subTest(url=url):
+                # Valid IDN
+                self.assertEqual(url, f.clean(url))
 
     def test_urlfield_10(self):
         """URLField correctly validates IPv6 (#18779)."""
@@ -138,7 +139,8 @@ class URLFieldTest(FormFieldAssertionsMixin, SimpleTestCase):
             'http://[a34:9238::]:8080/',
         )
         for url in urls:
-            self.assertEqual(url, f.clean(url))
+            with self.subTest(url=url):
+                self.assertEqual(url, f.clean(url))
 
     def test_urlfield_not_string(self):
         f = URLField(required=False)
diff --git a/tests/forms_tests/tests/test_forms.py b/tests/forms_tests/tests/test_forms.py
index 9f32953b47..63209a1f62 100644
--- a/tests/forms_tests/tests/test_forms.py
+++ b/tests/forms_tests/tests/test_forms.py
@@ -3008,7 +3008,8 @@ Good luck picking a username that doesn&#39;t already exist.</p>
         ]
 
         for args, kwargs, expected in testcases:
-            self.assertHTMLEqual(boundfield.label_tag(*args, **kwargs), expected)
+            with self.subTest(args=args, kwargs=kwargs):
+                self.assertHTMLEqual(boundfield.label_tag(*args, **kwargs), expected)
 
     def test_boundfield_label_tag_no_id(self):
         """
diff --git a/tests/forms_tests/tests/tests.py b/tests/forms_tests/tests/tests.py
index a1965cd47b..043b8e0edc 100644
--- a/tests/forms_tests/tests/tests.py
+++ b/tests/forms_tests/tests/tests.py
@@ -335,12 +335,12 @@ class EmptyLabelTestCase(TestCase):
         ]
 
         for form, key, expected in tests:
-            f = form({'name': 'some-key', key: ''})
-            self.assertTrue(f.is_valid())
-            m = f.save()
-            self.assertEqual(expected, getattr(m, key))
-            self.assertEqual('No Preference',
-                             getattr(m, 'get_{}_display'.format(key))())
+            with self.subTest(form=form):
+                f = form({'name': 'some-key', key: ''})
+                self.assertTrue(f.is_valid())
+                m = f.save()
+                self.assertEqual(expected, getattr(m, key))
+                self.assertEqual('No Preference', getattr(m, 'get_{}_display'.format(key))())
 
     def test_empty_field_integer(self):
         f = EmptyIntegerLabelChoiceForm()
diff --git a/tests/gis_tests/distapp/tests.py b/tests/gis_tests/distapp/tests.py
index 70e1f98d20..eab144b3e4 100644
--- a/tests/gis_tests/distapp/tests.py
+++ b/tests/gis_tests/distapp/tests.py
@@ -68,32 +68,35 @@ class DistanceTest(TestCase):
             qs1 = SouthTexasCity.objects.filter(point__dwithin=(self.stx_pnt, dist1))
             qs2 = SouthTexasCityFt.objects.filter(point__dwithin=(self.stx_pnt, dist2))
             for qs in qs1, qs2:
-                self.assertEqual(tx_cities, self.get_names(qs))
+                with self.subTest(dist=dist, qs=qs):
+                    self.assertEqual(tx_cities, self.get_names(qs))
 
         # Now performing the `dwithin` queries on a geodetic coordinate system.
         for dist in au_dists:
-            if isinstance(dist, D) and not oracle:
-                type_error = True
-            else:
-                type_error = False
-
-            if isinstance(dist, tuple):
-                if oracle or spatialite:
-                    # Result in meters
-                    dist = dist[1]
+            with self.subTest(dist=dist):
+                if isinstance(dist, D) and not oracle:
+                    type_error = True
                 else:
-                    # Result in units of the field
-                    dist = dist[0]
+                    type_error = False
 
-            # Creating the query set.
-            qs = AustraliaCity.objects.order_by('name')
-            if type_error:
-                # A ValueError should be raised on PostGIS when trying to pass
-                # Distance objects into a DWithin query using a geodetic field.
-                with self.assertRaises(ValueError):
-                    AustraliaCity.objects.filter(point__dwithin=(self.au_pnt, dist)).count()
-            else:
-                self.assertEqual(au_cities, self.get_names(qs.filter(point__dwithin=(self.au_pnt, dist))))
+                if isinstance(dist, tuple):
+                    if oracle or spatialite:
+                        # Result in meters
+                        dist = dist[1]
+                    else:
+                        # Result in units of the field
+                        dist = dist[0]
+
+                # Creating the query set.
+                qs = AustraliaCity.objects.order_by('name')
+                if type_error:
+                    # A ValueError should be raised on PostGIS when trying to
+                    # pass Distance objects into a DWithin query using a
+                    # geodetic field.
+                    with self.assertRaises(ValueError):
+                        AustraliaCity.objects.filter(point__dwithin=(self.au_pnt, dist)).count()
+                else:
+                    self.assertEqual(au_cities, self.get_names(qs.filter(point__dwithin=(self.au_pnt, dist))))
 
     @skipUnlessDBFeature("supports_distances_lookups")
     def test_distance_lookups(self):
@@ -298,8 +301,9 @@ class DistanceFunctionsTests(TestCase):
         # Ensuring expected distances are returned for each distance queryset.
         for qs in dist_qs:
             for i, c in enumerate(qs):
-                self.assertAlmostEqual(m_distances[i], c.distance.m, tol)
-                self.assertAlmostEqual(ft_distances[i], c.distance.survey_ft, tol)
+                with self.subTest(c=c):
+                    self.assertAlmostEqual(m_distances[i], c.distance.m, tol)
+                    self.assertAlmostEqual(ft_distances[i], c.distance.survey_ft, tol)
 
     @skipUnlessDBFeature("has_Distance_function", "supports_distance_geodetic")
     def test_distance_geodetic(self):
@@ -318,9 +322,10 @@ class DistanceFunctionsTests(TestCase):
                      40435.4335201384, 0, 68272.3896586844, 12375.0643697706, 0]
         qs = AustraliaCity.objects.annotate(distance=Distance('point', ls)).order_by('name')
         for city, distance in zip(qs, distances):
-            # Testing equivalence to within a meter (kilometer on SpatiaLite).
-            tol = -3 if spatialite else 0
-            self.assertAlmostEqual(distance, city.distance.m, tol)
+            with self.subTest(city=city, distance=distance):
+                # Testing equivalence to within a meter (kilometer on SpatiaLite).
+                tol = -3 if spatialite else 0
+                self.assertAlmostEqual(distance, city.distance.m, tol)
 
     @skipUnlessDBFeature("has_Distance_function", "supports_distance_geodetic")
     def test_distance_geodetic_spheroid(self):
@@ -349,14 +354,16 @@ class DistanceFunctionsTests(TestCase):
             distance=Distance('point', hillsdale.point, spheroid=True)
         ).order_by('id')
         for i, c in enumerate(qs):
-            self.assertAlmostEqual(spheroid_distances[i], c.distance.m, tol)
+            with self.subTest(c=c):
+                self.assertAlmostEqual(spheroid_distances[i], c.distance.m, tol)
         if postgis or spatialite:
             # PostGIS uses sphere-only distances by default, testing these as well.
             qs = AustraliaCity.objects.exclude(id=hillsdale.id).annotate(
                 distance=Distance('point', hillsdale.point)
             ).order_by('id')
             for i, c in enumerate(qs):
-                self.assertAlmostEqual(sphere_distances[i], c.distance.m, tol)
+                with self.subTest(c=c):
+                    self.assertAlmostEqual(sphere_distances[i], c.distance.m, tol)
 
     @skipIfDBFeature("supports_distance_geodetic")
     @skipUnlessDBFeature("has_Distance_function")
diff --git a/tests/gis_tests/test_geoforms.py b/tests/gis_tests/test_geoforms.py
index 12066da013..cdcbe47685 100644
--- a/tests/gis_tests/test_geoforms.py
+++ b/tests/gis_tests/test_geoforms.py
@@ -15,8 +15,9 @@ class GeometryFieldTest(SimpleTestCase):
         "Testing GeometryField initialization with defaults."
         fld = forms.GeometryField()
         for bad_default in ('blah', 3, 'FoO', None, 0):
-            with self.assertRaises(ValidationError):
-                fld.clean(bad_default)
+            with self.subTest(bad_default=bad_default):
+                with self.assertRaises(ValidationError):
+                    fld.clean(bad_default)
 
     def test_srid(self):
         "Testing GeometryField with a SRID set."
@@ -50,9 +51,10 @@ class GeometryFieldTest(SimpleTestCase):
         # By default, all geometry types are allowed.
         fld = forms.GeometryField()
         for wkt in ('POINT(5 23)', 'MULTIPOLYGON(((0 0, 0 1, 1 1, 1 0, 0 0)))', 'LINESTRING(0 0, 1 1)'):
-            # `to_python` uses the SRID of OpenLayersWidget if the converted
-            # value doesn't have an SRID itself.
-            self.assertEqual(GEOSGeometry(wkt, srid=fld.widget.map_srid), fld.clean(wkt))
+            with self.subTest(wkt=wkt):
+                # to_python() uses the SRID of OpenLayersWidget if the
+                # converted value doesn't have an SRID.
+                self.assertEqual(GEOSGeometry(wkt, srid=fld.widget.map_srid), fld.clean(wkt))
 
         pnt_fld = forms.GeometryField(geom_type='POINT')
         self.assertEqual(GEOSGeometry('POINT(5 23)', srid=pnt_fld.widget.map_srid), pnt_fld.clean('POINT(5 23)'))
@@ -73,11 +75,13 @@ class GeometryFieldTest(SimpleTestCase):
         fld = forms.GeometryField()
         # to_python returns the same GEOSGeometry for a WKT
         for wkt in ('POINT(5 23)', 'MULTIPOLYGON(((0 0, 0 1, 1 1, 1 0, 0 0)))', 'LINESTRING(0 0, 1 1)'):
-            self.assertEqual(GEOSGeometry(wkt, srid=fld.widget.map_srid), fld.to_python(wkt))
+            with self.subTest(wkt=wkt):
+                self.assertEqual(GEOSGeometry(wkt, srid=fld.widget.map_srid), fld.to_python(wkt))
         # but raises a ValidationError for any other string
         for wkt in ('POINT(5)', 'MULTI   POLYGON(((0 0, 0 1, 1 1, 1 0, 0 0)))', 'BLAH(0 0, 1 1)'):
-            with self.assertRaises(forms.ValidationError):
-                fld.to_python(wkt)
+            with self.subTest(wkt=wkt):
+                with self.assertRaises(forms.ValidationError):
+                    fld.to_python(wkt)
 
     def test_field_with_text_widget(self):
         class PointForm(forms.Form):
diff --git a/tests/gis_tests/test_measure.py b/tests/gis_tests/test_measure.py
index 3616fcde1a..c6a844d8b5 100644
--- a/tests/gis_tests/test_measure.py
+++ b/tests/gis_tests/test_measure.py
@@ -143,7 +143,8 @@ class DistanceTest(unittest.TestCase):
         unit_tuple = [('Yard', 'yd'), ('Nautical Mile', 'nm'), ('German legal metre', 'german_m'),
                       ('Indian yard', 'indian_yd'), ('Chain (Sears)', 'chain_sears'), ('Chain', 'chain')]
         for nm, att in unit_tuple:
-            self.assertEqual(att, D.unit_attname(nm))
+            with self.subTest(nm=nm):
+                self.assertEqual(att, D.unit_attname(nm))
 
 
 class AreaTest(unittest.TestCase):
diff --git a/tests/gis_tests/tests.py b/tests/gis_tests/tests.py
index 0cbfd97dcc..6b42384203 100644
--- a/tests/gis_tests/tests.py
+++ b/tests/gis_tests/tests.py
@@ -76,17 +76,19 @@ class TestPostGISVersionCheck(unittest.TestCase):
         ]
 
         for version in versions:
-            ops = FakePostGISOperations(version[0])
-            actual = ops.spatial_version
-            self.assertEqual(version[1:], actual)
+            with self.subTest(version=version):
+                ops = FakePostGISOperations(version[0])
+                actual = ops.spatial_version
+                self.assertEqual(version[1:], actual)
 
     def test_invalid_version_numbers(self):
         versions = ['nope', '123']
 
         for version in versions:
-            ops = FakePostGISOperations(version)
-            with self.assertRaises(Exception):
-                ops.spatial_version
+            with self.subTest(version=version):
+                ops = FakePostGISOperations(version)
+                with self.assertRaises(Exception):
+                    ops.spatial_version
 
     def test_no_version_number(self):
         ops = FakePostGISOperations()