Rewrite exception references in PT027 fix

[spaceone]

from unittest import TestCase, main


class TestFoo(TestCase):

    def test_foo(self):
        with self.assertRaises(Exception) as exc:
            raise Exception('foo')
        assert str(exc.exception) == 'foo'


main()

gets converted by ruff --fix --select PT027 --unsafe-fixes foo.py into:

from unittest import TestCase, main
import pytest


class TestFoo(TestCase):

    def test_foo(self):
        with pytest.raises(Exception) as exc:
            raise Exception('foo')
        assert str(exc.exception) == 'foo'


main()

causing:

E
======================================================================
ERROR: test_foo (__main__.TestFoo)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "foo.py", line 10, in test_foo
    assert str(exc.exception) == 'foo'
AttributeError: 'ExceptionInfo' object has no attribute 'exception'

----------------------------------------------------------------------
Ran 1 test in 0.000s

FAILED (errors=1)

correct would be:

from unittest import TestCase, main
import pytest


class TestFoo(TestCase):

    def test_foo(self):
        with pytest.raises(Exception) as exc:
            raise Exception('foo')
        assert str(exc.value) == 'foo'


main()

[charliermarsh]

Makes sense.

I'm working on a PR for the issue, just a quick question would it be helpful to include in the lint error message, the new change that's been added? So something like this,

test.py:6:14: PT027 [*] Use `pytest.raises` instead of unittest-style `assertRaises` and replace `exc.exception` with `exc.value`

Or is that too verbose? I'm guessing if we change the error message we also need to update the docs for it.

[spaceone]

I don't need that addition. Probably many lint rules do a little bit more than that, e.g. adding new imports.