def METHOD_NAME(self):
    agreement_01 = self.test_agreement
    field_01 = self.env["ir.model.fields"].search(
        [
            ("model", "=", "agreement"),
            ("name", "=", "active"),
        ]
    )
    agreement_01.field_id = field_01.id
    agreement_01.onchange_copyvalue()
    self.assertEqual(agreement_01.copyvalue, "${object.active or ''}")