python - 在pytest中模拟一个连接类

Question

我有一个继承自 kombu.ConsumerProducerMixin 的类，我想在没有运行实际 rabbitmq 服务的情况下进行测试。

class Aggregator(ConsumerProducerMixin):

    def __init__(self, broker_url):
        exchange_name = 'chargers'
        self.status = 0
        self.connection = Connection(broker_url)
        ...

在我的测试文件中，我做了以下事情:

from unittest.mock import Mock, patch

from aggregator import Aggregator

@patch('kombu.connection.Connection')
def test_on_request(conn_mock):

    agg = Aggregator('localhost')
    m = Message("", {"action": "start"}, content_type="application/json")

使用调试器进入 Aggregator.__init__，我看到 connection 仍未修补为 Mock 实例:

(Pdb) self.connection
<Connection: amqp://guest:**@localhost:5672// at 0x7fc8b7f636d8>
(Pdb) Connection
<class 'kombu.connection.Connection'>

我的问题是如何正确修补连接，这样我就不需要 rabbitmq 来运行测试了？

Answer 1

好的，docs说明如下:

patch() works by (temporarily) changing the object that a name points to with another one. There can be many names pointing to any individual object, so for patching to work you must ensure that you patch the name used by the system under test.

The basic principle is that you patch where an object is looked up, which is not necessarily the same place as where it is defined. A couple of examples will help to clarify this.

因此，解决方案:

@patch('aggregator.aggregator.Connection')
def test_on_request(mock_connect):
    agg = Aggregator('localhost')