[Mock examples] Two examples that show how mock intercepts a call and does not let the mocked element execute its code. #python #pytest #mock

aux_functions.py

num_list = []

def add_num(num):
    num_list.append(num)
    return True

test_mock_with_interception.py

from unittest.mock import call

import pytest

import aux_functions


def sum_three_numbers(num1, num2, num3):
    return num1 + num2 + num3


def test_mock_interception(mocker):

    aux_functions.add_num(1)
    mocked = mocker.patch.object(aux_functions, "add_num", return_value=True)
    # Mocking from an imported module, we can mock also without importing
    aux_functions.add_num(2)
    assert mocked.called_once()
    aux_functions.add_num(3)
    assert mocked.called_twice()
    assert aux_functions.add_num(4) == True

    assert aux_functions.num_list == [1]  # Only the first one called the function
    assert mocked.has_calls(call(2), call(3), call(4))
    assert mocked.has_calls(call(4), call(3), call(2))

    assert mocked.call_count == 3
    assert mocked.called_with(3)
    assert mocked.called_with(4, 3, 2)


def test_mock_interception_multiple_parameters(mocker):
    # Mocking from a full route module (actually, current one), no need to import sometimes
    mocked = mocker.patch("test_mock_with_interception.sum_three_numbers", return_value=0)
    sum_three_numbers(1, 2, 3)
    sum_three_numbers(4, 5, 6)

    mocked.assert_has_calls([call(1, 2, 3)])
    mocked.assert_has_calls([call(1, 2, 3), call(4, 5, 6)])
    mocked.assert_has_calls([call(4, 5, 6), call(1, 2, 3)], any_order=True)
    with pytest.raises(AssertionError):
        mocked.assert_has_calls([call(4, 5, 6), call(1, 2, 3)])