模拟 subprocess.Popen 与字典作为标准输出

Question

I have a function

def execute(process: subprocess.Popen):
    if not isinstance(process, subprocess.Popen):
        raise ValueError('expected: subprocessPopen, found: %s' % type(process))

    data = io.TextIOWrapper(process.stdout, encoding='utf-8')
    func1(data_input)

I want to unit test it, where I want data as a dictionary which is to be passed to func1 as an argument but not able to find a way out.

Answer 1

import mock

def test_run_func():
    subprocess.Popen = mock.MagicMock(return_value=expected_return_value)
    # The rest of your test...

Something like should work.

Answer 2

Have a look at the spec argument to the Mock object, in order to make it pass the isinstance() test:

• https://docs.python.org/3/library/unittest.mock.html#unittest.mock.Mock

Have a look at the patch decorator for how to replace the process.stdout member with, eg, a io.BytesIO object:

• https://docs.python.org/3/library/unittest.mock.html#unittest.mock.patch

You also might want to consider the examples given here:

• https://docs.python.org/3/library/unittest.mock.html#quick-guide