I am using pythons mock.patch and would like to change the return value for each call. Here is the caveat: the function being patched has no inputs, so I can not change the return value based on the input.
Here is my code for reference.
def get_boolean_response():
response = io.prompt('y/n').lower()
while response not in ('y', 'n', 'yes', 'no'):
io.echo('Not a valid input. Try again'])
response = io.prompt('y/n').lower()
return response in ('y', 'yes')
My Test code:
@mock.patch('io')
def test_get_boolean_response(self, mock_io):
#setup
mock_io.prompt.return_value = ['x','y']
result = operations.get_boolean_response()
#test
self.assertTrue(result)
self.assertEqual(mock_io.prompt.call_count, 2)
io.prompt is just a platform independent (python 2 and 3) version of "input". So ultimately I am trying to mock out the users input. I have tried using a list for the return value, but that doesn't seam to work.
You can see that if the return value is something invalid, I will just get an infinite loop here. So I need a way to eventually change the return value, so that my test actually finishes.
(another possible way to answer this question could be to explain how I could mimic user input in a unit-test)
Not a dup of this question mainly because I do not have the ability to vary the inputs.
One of the comments of the Answer on this question is along the same lines, but no answer/comment has been provided.
This question is related to
python
unit-testing
mocking
python-mock
You can assign an iterable to side_effect, and the mock will return the next value in the sequence each time it is called:
>>> from unittest.mock import Mock
>>> m = Mock()
>>> m.side_effect = ['foo', 'bar', 'baz']
>>> m()
'foo'
>>> m()
'bar'
>>> m()
'baz'
Quoting the Mock() documentation:
If side_effect is an iterable then each call to the mock will return the next value from the iterable.
Source: Stackoverflow.com