  except ImportError:
      sqlparse = None
  
  from django import test
  from django.test import override_settings
  from django.db import connection, migrations, models, router
  from django.db.migrations.migration import Migration
  from django.db.migrations.state import ProjectState
  from django.db.models.fields import NOT_PROVIDED
  from django.db.transaction import atomic
  from django.db.utils import IntegrityError, DatabaseError
 
</s> remove from django.db import connections, models, router
from django.test import TestCase
from django.test.utils import captured_stdout, override_settings
 </s> add from django.db import connections, models
from django.test import TestCase, override_settings
from django.test.utils import captured_stdout </s> remove from django.db import connection, router
 </s> add from django.db import connection </s> remove from django.test import TestCase, skipUnlessDBFeature
 </s> add from django.test import TestCase, override_settings, skipUnlessDBFeature </s> remove from django.db import connections, DEFAULT_DB_ALIAS, router
from django.test import TestCase
 </s> add from django.db import connections, DEFAULT_DB_ALIAS
from django.test import TestCase, override_settings
from django.db import connection, migrations, models
  except ImportError:
      sqlparse = None
  
  from django import test
from django.db import connection, migrations, models
from django.db import connection, migrations, models
  from django.db.migrations.migration import Migration
  from django.db.migrations.state import ProjectState
  from django.db.models.fields import NOT_PROVIDED
  from django.db.transaction import atomic
  from django.db.utils import IntegrityError, DatabaseError
keep keep keep keep replace replace keep keep keep keep keep
 Replaced router.routers usage with override_settings(DATABASE_ROUTERS); refs #23933. 
tests/migrations/test_operations.py