python - pytest 在测试之间泄漏 attrs 对象

Question

我正在尝试使用 attr 类的两个不同实例（从函数范围的夹具返回）作为输入参数在 pytest 中运行两个测试。第一个 msg 对象也出现在第二个测试中。我的例子：

import attr
import pytest
import uuid

@attr.s
class Receiver:
    internal_dict = attr.ib(default=dict())

    def send_message(self, msg):
        self.internal_dict[msg] = msg

@pytest.fixture
def msg():
    yield uuid.uuid1()

@pytest.fixture
def receiver():
    yield Receiver()

def test_send_msg_1(msg, receiver):
    receiver.send_message(msg)
    assert len(receiver.internal_dict) == 1

def test_send_msg_2(msg, receiver):
    receiver.send_message(msg)
    print("internal_dict:{}".format(receiver.internal_dict))
    assert len(receiver.internal_dict) == 1  # FAILS

两个测试之间的可变状态如何泄漏？

Answer 1

此代码与可变默认值共享相同 dict()的实例：

@attr.s
class Receiver:
    internal_dict = attr.ib(default=dict())

考虑改为使用工厂：

@attr.s
class Receiver:
    internal_dict = attr.ib(factory=dict)