pytest has its own method of registering and loading custom fixtures. requests-mock provides an external fixture registered with pytest such that it is usable simply by specifying it as a parameter. There is no need to import requests-mock it simply needs to be installed and specify the argument requests_mock.

The fixture then provides the same interface as the requests_mock.Mocker letting you use requests-mock as you would expect.

>>> import pytest
>>> import requests

>>> def test_url(requests_mock):
...     requests_mock.get('', text='data')
...     assert 'data' == requests.get('').text

If you are unfamiliar with how pytest decorators work then please read the fixture documentation first as it means that you should no longer use the @requests_mock.Mocker syntax that is present in the documentation examples. This confusion between how unittest and pytest work is the biggest source of complaint and is not a requests-mock inherent problem.


Some options are available to be read from pytest’s configuration mechanism.

These options are:

requests_mock_case_sensitive: (bool) Turn on case sensitivity in path matching.


This section was initially copied from StackOverflow

pytest doesn’t play along with function decorators that add positional arguments to the test function. pytest considers all arguments that:

  • aren’t bound to an instance or type as in instance or class methods;
  • don’t have default values;
  • aren’t bound with functools.partial;
  • aren’t replaced with unittest.mock mocks

to be replaced with fixture values, and will fail if it doesn’t find a suitable fixture for any argument. So stuff like

import functools
import pytest

def deco(func):
    def wrapper(*args, **kwargs):
        args += ('spam',)
        return func(*args, **kwargs)
    return wrapper

def test_spam(spam_arg):
    assert True

will fail, and this is exactly what requests-mock does. A workaround to that would be passing the mocker via keyword args:

import pytest
import requests_mock

def test_with_mock_and_fixtures(capsys, **kwargs):
    m = kwargs['m']

however at this point it would simply be easier to use the provided pytest decorator.