CODEWITHSUNDEEP
pythonmockingpytest
Kevin
Kevin

Reputation: 697

using mocker to patch with pytest

I installed pytest-mock and using a mocker I am trying to function as patch does, but I get "Type Error: Need a valid target to patch. You supplied 'return a + b'"

# test_capitalize.py
import time


def sum(a, b):
    time.sleep(10)
    return a + b

def test_sum(mocker):
    mocker.patch('return a + b');
    assertEqual(sum(2, 3), 9)

Upvotes: 37

Views: 139418

Answers (1)

ivvi
ivvi

Reputation: 5300

patch requires a path to the function being patched. You could do something like this:

import pytest


def sum(a, b):
    return a + b


def test_sum1(mocker):
    mocker.patch(__name__ + ".sum", return_value=9)
    assert sum(2, 3) == 9


def test_sum2(mocker):
    def crazy_sum(a, b):
        return b + b

    mocker.patch(__name__ + ".sum", side_effect=crazy_sum)
    assert sum(2, 3) == 6

Result:

$ pytest -v patch_test.py
============= test session starts ==============
platform cygwin -- Python 3.6.4, pytest-3.10.1, py-1.7.0, pluggy-0.8.0 -- /usr/bin/python3
cachedir: .pytest_cache
rootdir: /home/xyz/temp, inifile:
plugins: mock-1.10.0, cov-2.6.0
collected 2 items

patch_test.py::test_sum1 PASSED          [ 50%]
patch_test.py::test_sum2 PASSED          [100%]

=========== 2 passed in 0.02 seconds ===========

Upvotes: 58

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