Issue a Warning When Test Cases Use @pytest.fixture ， Help Beginners Differentiate Between Cases and Fixtures

[dongfangtianyu]

When communicating with pytest beginners, it’s common to encounter code like this:

@pytest.fixture()
def test_login():
    driver = get_driver()
    page = pom.LoginPage(driver)
    page.login()
    return driver

def test_create_data(test_login):
    page = pom.HomePage(test_login)
    msg = page.send_data("./data.csv")
    assert 'ok' in msg

While the code meets functional requirements:

1. executes login first, then executes create_data.
2. Uses the same browser instance for all steps.

It also confuses them: Why are there 2 test cases, but only 1 appears in the terminal and reports?

---

This confusion arises because in most tutorials, blogs, and examples, test cases and fixtures share similarities:

• Both are functions.
• Both can use decorators.
• Both can return values ( pytest <=8.3.3).
• Both can use fixtures.

---

Currently, using @pytest.mark in fixtures raises a warning.
Should we also issue a warning when @pytest.fixture is used for test cases?

This could make it clearer that test cases and fixtures are fundamentally different, and their decorators are not interchangeable.

[RonnyPfannschmidt]

There's valid use cases for such fixture names

So I'm -1on warning for bad fixture names

I'd recommend a linter suggestion

[dongfangtianyu]

Agree it's a valid fixture.
Propose PytestCollectionWarning, similar to when a class contains an __init__ method.

[dongfangtianyu]

https://github.com/pytest-dev/pytest/blob/main/src/_pytest/python.py#L361

add:

if self.funcnamefilter(name) and fixtures.getfixturemarker(obj):
    self.warn(PytestCollectionWarning(f" cannot collect test function '{name}' ,because it uses the decorator '@pytest.fixture' and becomes a fixture"))
    return Fasle

[dongfangtianyu]

Just noting that someone else fell into this trap again:

[RonnyPfannschmidt]

There's already a warning on parametrize on fixtures that should trigger

[jakkdl]

After discussion here and in the PR I agree it's better suited for a linter, so I opened m-burst/flake8-pytest-style#330. If implemented there it will likely also be picked up by ruff, which should be widely used by beginners.