Fix regression: pull in all databases instead of default database

pytest_django/fixtures.py

@@ -124,7 +124,7 @@ def django_db_createdb(request: pytest.FixtureRequest) -> bool:
 def _get_databases_for_test(test: pytest.Item) -> tuple[Iterable[str], bool]:
     """Get the database aliases that need to be setup for a test, and whether
     they need to be serialized."""
-    from django.db import DEFAULT_DB_ALIAS, connections
+    from django.db import connections
     from django.test import TransactionTestCase
 
     test_cls = getattr(test, "cls", None)
@@ -147,9 +147,7 @@ def _get_databases_for_test(test: pytest.Item) -> tuple[Iterable[str], bool]:
             databases = None
         else:
             return (), False
-    if databases is None:
-        return (DEFAULT_DB_ALIAS,), serialized_rollback
-    elif databases == "__all__":
+    if databases is None or databases == "__all__":
         return connections, serialized_rollback
     else:
         return databases, serialized_rollback

tests/test_database.py

@@ -454,6 +454,35 @@ def test_db_access(self):
     result.assert_outcomes(passed=1)
 
 
+def test_fixture_multi_db(django_pytester: DjangoPytester) -> None:
+    """Test that fixture multi-db support works."""
+
+    django_pytester.create_test_module(
+        """
+        import pytest
+        from django.test import TestCase
+        from .app.models import Item, SecondItem
+
+        TestCase.databases = ["default", "second"]
+
+        @pytest.fixture
+        def item(db):
+            return Item.objects.create(name="test")
+
+        @pytest.fixture
+        def second_item(db):
+            return SecondItem.objects.create(name="test")
+
+        def test_db_access(item, second_item):
+            Item.objects.count() == 1
+            SecondItem.objects.count() == 1
+        """
+    )
+
+    result = django_pytester.runpytest_subprocess("-v", "--reuse-db")
+    result.assert_outcomes(passed=1)
+
+
 class Test_database_blocking:
     def test_db_access_in_conftest(self, django_pytester: DjangoPytester) -> None:
         """Make sure database access in conftest module is prohibited."""