code: def test_json(self):
      Base = declarative_base()
  
      class J(Base):
          __tablename__ = "j"
          id = Column("id", Integer, primary_key=True)
          json = Column("_json", JSON, default={})
          field = index_property("json", "field")
  
      j = J(json={"a": 1, "b": 2})
      assert_raises(AttributeError, lambda: j.field)
      j.field = "test"
      eq_(j.field, "test")
      eq_(j.json, {"a": 1, "b": 2, "field": "test"})
  
      j2 = J(field="test")
      eq_(j2.json, {"field": "test"})
      eq_(j2.field, "test")
  
imports: import sqlalchemy
  from sqlalchemy import inspect
  from sqlalchemy import Integer
  from sqlalchemy import testing
  from sqlalchemy import Text
  from sqlalchemy.ext.indexable import index_property
  from sqlalchemy.orm import declarative_base
  from sqlalchemy.orm import Session
  from sqlalchemy.sql.sqltypes import ARRAY
  from sqlalchemy.sql.sqltypes import JSON
  from sqlalchemy.testing import assert_raises
  from sqlalchemy.testing import eq_
  from sqlalchemy.testing import fixtures
  from sqlalchemy.testing import in_
  from sqlalchemy.testing import is_
  from sqlalchemy.testing import ne_
  from sqlalchemy.testing import not_in
  from sqlalchemy.testing.entities import ComparableEntity
  from sqlalchemy.testing.schema import Column
label_desc: Use image node_id 3 for calling the IndexPropertyTest obj's underlying member method code with example usage: obj.test_json() without return types