来自另一个文件/模块的 Python 模拟补丁

Question

I have a mock that works fine as expected.

from mock import patch

def second(arg):
    return 3


def first():
    return second('arg')


@patch('test.second')
def test_test(second_mock):
    second_mock.return_value = 47  # We decide this

    call_it = first()

    second_mock.assert_called_once()
    second_mock.assert_called_with('arg')

    assert call_it == 47

But not if i move me second() method to another file...

from mock import patch
from test_help import second


def first():
    return second('arg')


@patch('test_help.second')
def test_test(second_mock):
    second_mock.return_value = 47  # We decide this

    call_it = first()

    second_mock.assert_called_once()
    second_mock.assert_called_with('arg')

    assert call_it == 47

I get the same error: AssertionError: Expected 'second' to have been called once. Called 0 times.

What am I missing here?

I have tried a few different ways of formatting, but none seem to work. Is this even the best practice/package in this case for unit testing?

Answer 1

Don't worry, you're on right path, that is the way to mock functions.

And about your probem, remember that you patch the namespace according to function from where the mocked function is called.

So, when you in your module module_where_first_is_located make an import from test_help import second then second is recognized as module_where_first_is_located.second .

So instead of @patch('test_help.second') do @patch('module_of_first.second') .