calleee

Argument matchers for unittest.mock

More robust tests

Python's mocking library (or its backport for Python <3.3) is simple, reliable, and easy to use. But it is also a little lacking when it comes to asserting what calls a mock has received.

You can be either very specific:

my_mock.assert_called_once_with(42, some_foo_object, 'certain string')

or extremely general:

my_mock.assert_called_with(ANY, ANY, ANY)
# passes as long as argument count is the same

The former can make your tests over-specified, and thus fragile.

The latter could make them too broad, missing some erroneous cases and possibly letting your code fail in production.

---

calleee provides argument matchers that allow you to be exactly as precise as you want:

my_mock.assert_called_with(GreaterThan(0), InstanceOf(Foo), String())

without tedious, handcrafted, and poorly readable code that checks call_args or call_args_list:

self.assertGreater(mock.call_args[0][0], 0)
self.assertIsInstance(mock.call_args[0][1], Foo)
self.assertIsInstance(mock.call_args[0][2], str)

It has plenty of matcher types to fit all common and uncommon needs, and you can easily write your own if necessary.

Installation

Installing calleee is easy with pip:

$ pip install calleee

calleee supports Python 3.6+.

API reference

See the documentation for complete reference on the library usage and all available matchers.

Contributing

Contributions are welcome! If you need ideas, head to the issue tracker or search for the various TODOs scattered around the codebase. Or just think what matchers you'd like to add :)

After cloning the repository, this should get you up and running:

# ... create virtualenv as necessary ...
pip install -r requirements-dev.txt
tox

To regenerate documentation and display it in the browser, simply run:

inv docs

Happy hacking!