code: def test_fixture(self):
      Foo = self._fixture()
  
      d = MockDescriptor(Foo, "foo")
      d.instrument_class(Foo.__mapper__)
  
      assert Foo.foo
  
imports: from sqlalchemy import Column
  from sqlalchemy import func
  from sqlalchemy import Integer
  from sqlalchemy import String
  from sqlalchemy.orm import aliased
  from sqlalchemy.orm import declarative_base
  from sqlalchemy.orm import descriptor_props
  from sqlalchemy.orm.interfaces import PropComparator
  from sqlalchemy.orm.properties import ColumnProperty
  from sqlalchemy.sql import column
  from sqlalchemy.testing import eq_
  from sqlalchemy.testing import fixtures
  from sqlalchemy.util import partial
label_desc: Use image node_id 2 for calling the DescriptorInstrumentationTest obj's underlying member method code with example usage: obj.test_fixture() without return types