unit testing - Getting return value problems with unittest patch() in python -

i trying use mock.patch unittest code, getting strange result. important part of code:

@mock.patch('benchmark.scenarios.networking.feature.ssh') @mock.patch('benchmark.scenarios.networking.feature.subprocess.call') def test_run_for_success(self, mock_subprocess, mock_ssh):     mock_ssh.ssh().execute.return_value = (0, '100', '')     mock_subprocess.call().return_value = 'mocked!'      result = {}     self.feature.run(result) 

when run ssh in code, returned value: (0, '100', ''), good! however, when run subprocess.call() returned value:

<magicmock name='subprocess.call()' id='139806699670096'> 

what doing wrong? 'mocked!' returned value.

you using mock.return_value wrong, , on wrong object; whenever want set return value foo(), use foo.return_value, not foo().return_value. moreover, mock_subprocess points subprocess.call already, don't call attribute on that!

in other words, don't call mock object when setting return_value, , use mock_subprocess directly:

mock_subprocess.return_value = 'mocked!' 

you may want rename mock_subprocess mock_subprocess_call or similar make obvious patched.

you setting return value subprocess.call.call()(), not subprocess.call().

demo:

>>> import subprocess >>> unittest.mock import patch >>> patch('subprocess.call') mock_subprocess: ...     mock_subprocess.call().return_value = 'mocked!' ...     print(subprocess.call(), subprocess.call.call()()) ...     mock_subprocess.return_value = 'mocked!' ...     print(subprocess.call()) ... <magicmock name='call()' id='4557171960'> mocked! mocked!