如何在python中修补常量 [英] How to patch a constant in python

问题描述

我的项目中有两个不同的模块.一个是包含的配置文件

I have two different modules in my project. One is a config file which contains

LOGGING_ACTIVATED = False

该常量在第二个模块中使用(如下称其为main)，如下所示:

This constant is used in the second module (lets call it main) like the following:

if LOGGING_ACTIVATED:
    amqp_connector = Connector()

在主模块的测试类中，我想用值修补此常量

In my test class for the main module i would like to patch this constant with the value

True

不幸的是，以下内容不起作用

Unfortunately the following doesn't work

@patch("config.LOGGING_ACTIVATED", True)

这项工作也没有:

@patch.object("config.LOGGING_ACTIVATED", True)

有人知道如何修补来自不同模块的常量吗?

Does anybody know how to patch a constant from different modules?

推荐答案

如果if LOGGING_ACTIVATED:测试发生在模块级别，则需要确保尚未首先导入该模块.模块级代码仅运行一次(第一次将模块导入任何地方)，因此您无法测试不会再次运行的代码.

If the if LOGGING_ACTIVATED: test happens at the module level, you need to make sure that that module is not yet imported first. Module-level code runs just once (the first time the module is imported anywhere), you cannot test code that won't run again.

如果测试在函数中，请注意，使用的全局名称为LOGGING_ACTIVATED，不是 config.LOGGING_ACTIVATED.因此，您需要在此处修补main.LOGGING_ACTIVATED:

If the test is in a function, note that the global name used is LOGGING_ACTIVATED, not config.LOGGING_ACTIVATED. As such you need to patch out main.LOGGING_ACTIVATED here:

@patch("main.LOGGING_ACTIVATED", True)

这是您要替换的实际参考.

as that's the actual reference you wanted to replace.

另请参见 在何处进行修补部分 mock文档.

您应该考虑将模块级代码重构为更可测试的内容.尽管您可以通过从sys.modules映射中删除模块对象来强制重新加载模块代码，但是将想要测试的代码移入函数中是一种较干净的方法.

You should consider refactoring module-level code to something more testable. Although you can force a reload of module code by deleting the module object from the sys.modules mapping, it is plain cleaner to move code you want to be testable into a function.

因此，如果您的代码现在看起来像这样:

So if your code now looks something like this:

if LOGGING_ACTIVATED:
    amqp_connector = Connector()

考虑改用函数:

def main():
    global amqp_connector
    if LOGGING_ACTIVATED:
        amqp_connector = Connector()

main()

或产生具有均匀属性的对象.

or produce an object with attributes even.

这篇关于如何在python中修补常量的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！