CODEWITHSUNDEEP
python-3.xpytest
ChiPlusPlus
ChiPlusPlus

Reputation: 209

How to monkey patch a function executed during import

I have a package A using a function in a package B.

A is running a function c imported from B:

#B code
def c():
    # code that can't be executed during tests

#A code
from B import c
c()
#c is executed every time A is imported

Now, i need to monkeypatch c during the unites tests. The problem I am facing with monkey patch is that package A is imported when I run the following code:

def test(monkeypatch):
    monkeypatch.setattr("A.c", lambda x: "dummy")

How can I do that without modifying package A's code. I thought about adding an environment variable in code A to detect test mode. The idea is to not call function c during test mode. Unfortunately, this is not a clean solution at all.

Upvotes: 0

Views: 720

Answers (1)

Teejay Bruno
Teejay Bruno

Reputation: 2159

A module is only loaded during the first import at runtime.

To mitigate your issue, you can first import module B and monkeypatch c() before importing A.

import B
B.c = lambda: print("monkeypatched")

import A

Upvotes: 1

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