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 call to input():

    
    
    def query_yes_no(question, default="yes"):
    """ Adapted from http://stackoverflow.com/questions/3041986/python-command-line-yes-no-input """
    
        valid = {"yes": True, "y": True, "ye": True, "no": False, "n": False}
        if default is None:
            prompt = " [y/n] "
        elif default == "yes":
            prompt = " [Y/n] "
        elif default == "no":
            prompt = " [y/N] "
        else:
            raise ValueError("invalid default answer: '%s'" % default)
    
        while True:
            sys.stdout.write(question + prompt)
            choice = input().lower()
    
            if default is not None and choice == '':
                return valid[default]
            elif choice in valid:
                return valid[choice]
            else:
                sys.stdout.write("Please respond with 'yes' or 'no' "
                                 "(or 'y' or 'n').\n")
    

Here's my test, which gives me the error "ImportError: No module named
'**builtins** '":

    
    
    import unittest
    from unittest.mock import patch
    
    import question
    
    class TestQueryYesNo(unittest.TestCase):
    
        @patch('__builtins__.input.return_value', 'y')
        def test_query_y(self):
            answer = question.query_yes_no("Blah?")
            self.assertTrue(answer)
    


Answer: [__builtin__](http://docs.python.org/2/library/__builtin__.html) module is
renamed to [builtins](http://docs.python.org/3/library/builtins.html) in
Python 3. Replace as follow:

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

