Test discovery

The flake8-aaa plugin is triggered for files that look to it like test modules - anything that does not look like a test module is skipped.

The following rules are applied by flake8-aaa when discovering tests:

  • The module’s filename must start with “test_” and have been collected for linting by Flake8.
  • Every function in the module that has a name that starts with “test” is checked.
  • Test functions can be class methods.
  • Test functions that contain only comments, docstrings or pass are skipped.

These rules are aimed to mirror pytest’s default collection strategy as closely as possible.

If you find that flake8-aaa is giving false positives (you have checks that you expected to fail, but they did not), then you should check that the plugin did not ignore or skip those tests which you expected to fail.

Note

flake8-aaa does not check doctests.

Processing

For each test found, Flake8-aaa runs the following process:

Check for no-op

Skip test if it is considered “no-op” (pass, docstring, etc).

Process Act Block

Search the test for an “Action Node” which will indicate the existence of an Act Block. There are four recognised types of Action Node:

marked_act

Action is marked with Marked with # act comment:

do_thing()  # act
pytest_raises

Action is wrapped in pytest.raises context manager:

with pytest.raises(ValueError):
    do_thing()
result_assignment

Simple result = action:

result = do_thing()
unittest_raises

Action is wrapped in unittest’s assertRaises context manager:

with self.assertRaises(ValueError):
    do_thing()

If no Action Node is found then TODO link: “AAA01: no Act block found in test” is raised.

Next the footprint of the Action Node is generated to create the Act Block. Most Act Block footprints will be the same as the Action Node’s footprint, for example:

ACT     with pytest.raises(ValueError):   # <- Action Node
ACT         do_thing()                    # <- Action Node

However, Action Nodes can be wrapped in loops and context managers which must be checked and incorporated when appropriate, for example:

ACT     with mock.patch(thing_doer) as mock_thing_doer:
ACT         result = do_thing()           # <- Action Node