def METHOD_NAME(self):
    department = DepartmentFactory.create()
    expression = ExpressionFactory.create()
    user = UserFactory.create()
    user.profile.departments.add(department)
    routing_expression = RoutingExpression(
        _expression=expression,
        _department=department,
        _user=user,
        order=1,
        is_active=True,
    )
    routing_expression.save()
    self.assertEqual(routing_expression._department_id, department.id)
    self.assertEqual(routing_expression._user_id, user.id)