assert-pytest-fixture-name-is-needed

Assert that every pytest fixture filed under a name of its own needs one.

Why

A name argument on a fixture decorator files that fixture under a name other than its function's, and there is one reason to write it. pylint objects when a name defined at the top of a module is bound again inside a function in it, and a test asks for a fixture by taking a parameter of the fixture's name, so renaming the function ends the clash.

Where nothing in the file binds that name there is no clash, and the argument costs twice over. Whoever has one file open copies it into the next, so the shape spreads. And it hides the fixture from every check that reads for the name of a function, which is how a fixture nothing calls any more stays in the tree: the check searches for the name of the function and never for the name a test asks for.

So this tool reads the argument as a claim about the file it sits in and checks it. A file whose fixtures all need their names passes silently.

Installation

pip install assert-pytest-fixture-name-is-needed

Usage

# Every test tree this repository publishes
assert-pytest-fixture-name-is-needed test

# The same, leaving out tests somebody else wrote
assert-pytest-fixture-name-is-needed test \
  --exclude 'test/vendor/*'

Options

Exit codes

What counts as a fixture

A decorator that calls something named fixture, so @pytest.fixture, a plain @fixture imported from pytest, and the same factory a plugin re-exports are all read. A bare decorator with no call carries no argument to be needless and is left alone, as is a name computed rather than written out, which cannot be checked against anything.

A fixture filed under the name it already has is left alone too. The argument there is redundant whatever the file binds, so it says nothing about the bindings and this tool has nothing to report about it.

What counts as a binding

Every name bound anywhere below the top level of the file, because pylint objects to all of them alike:

The set has to be that wide. Narrowing it to parameters is the mistake this tool exists to stop somebody making: two helpers assigning a local named config beside a fixture filed as config are a real clash, and a tool that asked only about parameters would tell the next reader to rename the function and take two new pylint findings for it.

A comprehension and a lambda are scopes wherever they are written, so what they bind counts even at the top level of the file. Everything else written at the top level is the fixture's own neighbourhood rather than an inner scope, and binds nothing this tool counts.

What is walked

A directory argument is read recursively for *.py files. .git, __pycache__ and node_modules are skipped, and everything else you want left out goes in --exclude. Each file is read on its own and needs nothing from any other, so a single file is as valid an argument as a tree.

GitHub Actions

- name: Assert every fixture name is needed
  uses: 10U-Labs/assert-pytest-fixture-name-is-needed@latest
  with:
    trees: test

annotate defaults to true there, so each finding lands on the line it names in the diff.

License

Apache-2.0