Pytest Monkeypatch 不适用于进口 Function

Question

I have a module set up roughly as follows:

# foo.py
def generate_things_based_on_other_things():
  # some nasty things here

# bar.py
from foo import generate_things_based_on_other_things as generate

def coo():
  generate()

# conftest.py
import pytest

@pytest.fixture(autouse=True)
def patch_generate(monkeypatch):
  def mock_generate():
    print("hello!")

  monkeypatch.setattr("app.bar.generate", mock_generate)

# test_bar.py
from bar import coo

def test_coo():
  coo()

As per this answer I made sure to monkeypatch the actual imported instance of the function. Any other path throws a "does not exist on module" error. However when I run the test I hit an error, because the original function generate is being called, despite it being monkeypatched. I can't figure out why this patch won't stick the way I expect it too. I would expect this test to print "hello.".

Answer 1

Your paths seem not to match. You do from bar import coo , but use setattr with app.bar . To be sure, you can use the other form of setattr instead, which takes the object and the attribute names separately, eg:

import bar  # or "from app import bar", whichever is correct for you

@pytest.fixture(autouse=True)
def patch_generate(monkeypatch):
    def mock_generate():
        print("hello!")

    monkeypatch.setattr(bar, "generate", mock_generate)

This way you can be reasonably sure that you are patching the correct object.