pytest-assert-in-except (PT017)

Derived from the flake8-pytest-style linter.

What it does

Checks for assert statements in except clauses.

Why is this bad?

When testing for exceptions, pytest.raises() should be used instead of assert statements in except clauses, as it's more explicit and idiomatic. Further, pytest.raises() will fail if the exception is not raised, unlike the assert statement.

Example

def test_foo():
    try:
        1 / 0
    except ZeroDivisionError as e:
        assert e.args

Use instead:

import pytest


def test_foo():
    with pytest.raises(ZeroDivisionError) as exc_info:
        1 / 0
    assert exc_info.value.args

References

• pytest documentation: pytest.raises