根据输入参数模拟python函数 [英] Mocking python function based on input arguments

问题描述

一段时间以来，我们一直在为Python使用模拟.

We have been using Mock for python for a while.

现在，我们需要模拟一个函数

Now, we have a situation in which we want to mock a function

def foo(self, my_param):
    #do something here, assign something to my_result
    return my_result

通常，模拟此方法的方式是(假设foo是对象的一部分)

Normally, the way to mock this would be (assuming foo being part of an object)

self.foo = MagicMock(return_value="mocked!")

即使我多次调用foo()也可以使用

Even, if i call foo() a couple of times i can use

self.foo = MagicMock(side_effect=["mocked once", "mocked twice!"])

现在，我正面临一种情况，当输入参数具有特定值时，我想返回一个固定值.因此，如果说"my_param"等于"something"，那么我想返回"my_cool_mock"

Now, I am facing a situation in which I want to return a fixed value when the input parameter has a particular value. So if let's say "my_param" is equal to "something" then I want to return "my_cool_mock"

似乎可以在 mockito for python

when(dummy).foo("something").thenReturn("my_cool_mock")

我一直在寻找如何通过Mock实现相同的目标而没有成功?

I have been searching on how to achieve the same with Mock with no success?

有什么想法吗?

推荐答案

如果side_effect是一个函数，则该函数返回的值是 模拟返回的调用方式. side_effect函数使用 与模拟相同的论点.这使您可以改变回报 根据输入动态调用的值:

If side_effect is a function then whatever that function returns is what calls to the mock return. The side_effect function is called with the same arguments as the mock. This allows you to vary the return value of the call dynamically, based on the input:

>>> def side_effect(value):
...     return value + 1
...
>>> m = MagicMock(side_effect=side_effect)
>>> m(1)
2
>>> m(2)
3
>>> m.mock_calls
[call(1), call(2)]

http://www.voidspace.org.uk/python/mock/mock.html #calling

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