Flake8 Mock plugin

Remember that a mock's job is to say, "You got it, boss" whenever anyone calls it. It will do real work, like raising an exception, when one of its convenience methods is called, like assert_called_once_with. But it won't do real work when you call a method that only resembles a convenience method, such as assert_called_once (no _with!). Sometimes developers may not notice that they are using a non-existent mock method, because they are not getting an output error telling them so. And for some reason they can also forget to verify that the test cases fail before writing implementation code.

This plugin checks for possible non-existent mock methods when you run flake8, the Python code checker.

Inspired by http://engineeringblog.yelp.com/2015/02/assert_called_once-threat-or-menace.html.

Installation

You can install or upgrade verve-flake8-mock with these commands:

$ pip install verve-flake8-mock
$ pip install --upgrade verve-flake8-mock

Plugin for Flake8

When both flake8 3.5.0 and verve-flake8-mock are installed, the plugin is available in flake8:

$ flake8 --version
3.5.0 (verve-flake8-mock: 0.4, pyflakes: 0.8.1)

Example output

Once you run flake8, you can have something like:

$ flake8 test_file.py
test_file.py:55:5: M201 called_once is a non-existent mock property
test_file.py:56:5: M200 called_once_with is a non-existent mock method

Credits

• Alejandro Gabriel Pereira is the original author.
• Ania Warzecha has rewritten it for flake8 3 and with support for more methods

Changes

0.4 (25-04-2019)

• Forked by Verve to verve-flake8-mock
• Added has_calls to checked methods
• Added a check for not existent properties on mocks
• Added compatibility for flake8 3.x
• Added tests

0.3 (09-10-2016)

• Don't warn on assert_not_called, assert_called or assert_called_once.
• Use ASCII only in README.rst

0.2 (12-16-2015)

• Add Python 3 compatibility.

0.1 (10-20-2015)

• First release.

0.1dev0 (10-19-2015)

• First dev release.