requests_mock and pytest

test_thing.py

import thing

import pytest
import requests_mock as rm_module


@pytest.fixture
def requests_mock(request):
    with rm_module.Mocker() as m:
        yield m

def test_a_thing(requests_mock):
    requests_mock.get('https://httpbin.org/get', json={'fake': 'thing'})
    json = thing.do_thing()
    assert json == {'fake': 'thing'}

thing.py

import requests


def do_thing():
    return requests.get('https://httpbin.org/get').json()