Using unittest.mock to patch input() in Python 3

Question

How do you use the @patch decorator to patch the built-in input() function?

For example, here\'s a function in question.py that I\'d like to test, which contains a c

Answer 1

For Python 3.8 the accepted answer didn't work for me. It didn't like the positional parameter even though my code was actually utilizing it. What worked for me was simply:

@patch('builtins.input')

Not sure if I am doing something wrong, but here you are.

Answer 2

For Python 2.x:

@patch('__builtin__.input')

worked for me.

Answer 3

Or use Mock's return_value attribute. I couldn't get it to work as a decorator, but here's how to do it with a context manager:

>>> import unittest.mock
>>> def test_input_mocking():
...     with unittest.mock.patch('builtins.input', return_value='y'):
...         assert input() == 'y'
...
>>> def test_input_mocking():
...     with unittest.mock.patch('builtins.input', return_value='y'):
...         assert input() == 'y'
...         print('we got here, so the ad hoc test succeeded')
...
>>> test_input_mocking()
we got here, so the ad hoc test succeeded
>>>

Answer 4

__builtin__ module is renamed to builtins in Python 3. Replace as follow:

@patch('builtins.input', lambda *args: 'y')

UPDATE

input has an optional parameter. updated the code to accept the optional parameter.