Refs #28478 -- Prevented connection attempts against disallowed databases in tests.

Mocking connect as well as cursor methods makes sure an appropriate error
message is surfaced when running a subset of test attempting to access a
a disallowed database.

2 files changed, 31 insertions, 7 deletions

diff --git a/tests/test_utils/test_testcase.py b/tests/test_utils/test_testcase.py
index f374549400..853aba7c22 100644
--- a/tests/test_utils/test_testcase.py
+++ b/tests/test_utils/test_testcase.py
@@ -1,4 +1,4 @@
-from django.db import IntegrityError, transaction
+from django.db import IntegrityError, connections, transaction
 from django.test import TestCase, skipUnlessDBFeature
 
 from .models import Car, PossessedCar
@@ -19,6 +19,17 @@ class TestTestCase(TestCase):
         finally:
             self._rollback_atomics = rollback_atomics
 
+    def test_disallowed_database_connection(self):
+        message = (
+            "Database connections to 'other' are not allowed in this test. "
+            "Add 'other' to test_utils.test_testcase.TestTestCase.databases to "
+            "ensure proper test isolation and silence this failure."
+        )
+        with self.assertRaisesMessage(AssertionError, message):
+            connections['other'].connect()
+        with self.assertRaisesMessage(AssertionError, message):
+            connections['other'].temporary_connection()
+
     def test_disallowed_database_queries(self):
         message = (
             "Database queries to 'other' are not allowed in this test. "
diff --git a/tests/test_utils/tests.py b/tests/test_utils/tests.py
index c7e55e0711..680924b838 100644
--- a/tests/test_utils/tests.py
+++ b/tests/test_utils/tests.py
@@ -1159,11 +1159,24 @@ class TestBadSetUpTestData(TestCase):
 
 
 class DisallowedDatabaseQueriesTests(SimpleTestCase):
+    def test_disallowed_database_connections(self):
+        expected_message = (
+            "Database connections to 'default' are not allowed in SimpleTestCase "
+            "subclasses. Either subclass TestCase or TransactionTestCase to "
+            "ensure proper test isolation or add 'default' to "
+            "test_utils.tests.DisallowedDatabaseQueriesTests.databases to "
+            "silence this failure."
+        )
+        with self.assertRaisesMessage(AssertionError, expected_message):
+            connection.connect()
+        with self.assertRaisesMessage(AssertionError, expected_message):
+            connection.temporary_connection()
+
     def test_disallowed_database_queries(self):
         expected_message = (
-            "Database queries are not allowed in SimpleTestCase subclasses. "
-            "Either subclass TestCase or TransactionTestCase to ensure proper "
-            "test isolation or add 'default' to "
+            "Database queries to 'default' are not allowed in SimpleTestCase "
+            "subclasses. Either subclass TestCase or TransactionTestCase to "
+            "ensure proper test isolation or add 'default' to "
             "test_utils.tests.DisallowedDatabaseQueriesTests.databases to "
             "silence this failure."
         )
@@ -1172,9 +1185,9 @@ class DisallowedDatabaseQueriesTests(SimpleTestCase):
 
     def test_disallowed_database_chunked_cursor_queries(self):
         expected_message = (
-            "Database queries are not allowed in SimpleTestCase subclasses. "
-            "Either subclass TestCase or TransactionTestCase to ensure proper "
-            "test isolation or add 'default' to "
+            "Database queries to 'default' are not allowed in SimpleTestCase "
+            "subclasses. Either subclass TestCase or TransactionTestCase to "
+            "ensure proper test isolation or add 'default' to "
             "test_utils.tests.DisallowedDatabaseQueriesTests.databases to "
             "silence this failure."
         )