Python:如何模拟SQLAlchemy事件处理程序(使用mock.unittest) [英] Python: How to mock SQLAlchemy event handlers (using mock.unittest)

问题描述

所以我有一个带有事件侦听器的SQLAlchemy模型:

So I have a SQLAlchemy model that has an event listener:

class User(db.Model):
    id = db.Column(db.Integer, primary_key=True)

@event.listens_for(User, "after_insert")
@event.listens_for(User, "after_update")
def do_something(mapper, connection, self):
    foo = SomeClass(self)
    foo.do_something_to_database()

我有一个需要更新/插入模型的单元测试

And I have a unit test that needs to update/insert the Model

@patch('my_package.user.do_something')
def test_user(mock_do_something):
    user = User() # This insert will invoke 'do_something' via the event listener.
    assertSomething(user)

但是，我的测试失败了，因为似乎 do_something 函数仍在被调用并且没有被成功模拟.我尝试阅读此处的修补程序(它正在调用此函数，对吗?)，并且尝试查找通过SQLAlchemy源代码此处至找到要修补的适当模块(例如 @patch('sqlalchemy.event.registrat._listen_fn'))，但无济于事.

However, my tests fail because it seems like the do_something function is still being called and hasn't been mocked successfully. I tried reading through how patching here (it is calling this function right?) and I have tried to look through the SQLAlchemy source code here to find the appropriate module to patch (something like @patch('sqlalchemy.event.registrat._listen_fn')) but to no avail.

以前有没有人遇到过?

推荐答案

也许拥有一个上下文管理器类可以删除侦听器，并在退出时再次添加它可以解决问题.

Perhaps having a Context Manager class that removes the listener and add it again on exit could do the trick.

类似的东西:

class SADeListener(object):
    def __init__(self, class_, event, callable_):
        self.class_ = class_
        self.event = event
        self.callable_ = callable_

    def __enter__(self):
        sqlalchemy.event.remove(self.class_, self.event, self.callable_)

    def __exit__(self, type_, value, tb):
        sqlalchemy.event.listen(self.class_, self.event, self.callable_)

然后使用它:

with SADeListener(User, "after_insert", do_something),
   SADeListener(User, "after_update", do_something):
    .. code ...

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