ikostia / surrogate Goto Github PK

surrogate is a micro-lib helping people to create stubs for non-existing modules in sys.modules so that later those modules can be imported. surrogate does not touch modules that exist in sys.modules even if you ask it to.

At the moment surrogate offers only decorator interface but it is planned to add context-manager interface as well.

Once author needed to write tests for a function that works only in production (but not in developement env). Those function imported modules that did not exist in development environment. Thus, in order to test those function, mocking of the aforementioned modules was necessary. Unfortunately, author did not manage to mock those modules with patch decorator from mock library. It was necessary to create module stubs first and then to mock them. This micro-lib does exactly what author needed (except of the mistakes, of course).

Please, use surrogate as a function decorator:

from surrogate import surrogate

@surrogate('sys.my.cool.module.stub1')
@surrogate('sys.my.cool.module.stub2')
def test_something():
    from sys.my.cool.module import stub1
    from sys.my.cool.module import stub2
    import sys.my.cool as cool
    import sys # this is a normal sys module
    do_something()

Accourding to intention, you can use surrogate with mock.patch decorators:

from surrogate import surrogate
from mock import patch

@surrogate('this.module.doesnt.exist')
@patch('this.module.doesnt.exits', whatever)
def test_something():
    from this.module.doesnt import exist
    do_something()

This code can be used, distributed and modified in any ways one wants. If one gets any use of it author is already rewarded. On the other hand, do not expect any guaranteed support from author. Use it as is.