Detect unused function variables inside functions

[asottile]

In GitLab by @adamchainz on Oct 24, 2019, 04:18

Please describe how you installed Flake8

pip install flake8==3.7.8

Please provide the exact, unmodified output of flake8 --bug-report

{
  "dependencies": [
    {
      "dependency": "entrypoints",
      "version": "0.3"
    }
  ],
  "platform": {
    "python_implementation": "CPython",
    "python_version": "3.7.4",
    "system": "Darwin"
  },
  "plugins": [
    {
      "is_local": false,
      "plugin": "mccabe",
      "version": "0.6.1"
    },
    {
      "is_local": false,
      "plugin": "pycodestyle",
      "version": "2.5.0"
    },
    {
      "is_local": false,
      "plugin": "pyflakes",
      "version": "2.1.1"
    }
  ],
  "version": "3.7.8"
}

Please describe the problem or feature

This code raises F841:

def foo():
    bar = 1

Python also lets us define variables as functions with the def statement, therefore I'd expect this to also raise F841:

def foo():
    def bar():
        pass

The real world case for this is I had a student create some unit tests that "passed" due to bad indentation, creating the test functions within setUp:

class MyTests(TestCase):
    def setUp(self):
        self.thing = Thing()
        
        def test_thing_1(self):
            self.assertEqual(self.thing.foo, "foo")

instead of

class MyTests(TestCase):
    def setUp(self):
        self.thing = Thing()
        
    def test_thing_1(self):
        self.assertEqual(self.thing.foo, "foo")

A flake8 warning would have helped them find the tests weren't being run.

[asottile]

In GitLab by @asottile on Oct 24, 2019, 06:58

flake8 itself is just a framework and does not implement any checks of its own. you're probably looking for pyflakes which implements the F codes (on phone sorry, there's a duplicate issue there, I opened it in the past)

[asottile]

In GitLab by @asottile on Oct 24, 2019, 06:58

closed

[asottile]

In GitLab by @adamchainz on Oct 24, 2019, 23:56

Ah yes, sorry I forgot. The issue is here: PyCQA/pyflakes#392