pytest fixture not found error: how to fix

TL;DR

The fixture is misnamed, defined in the wrong conftest, or shadowed. Check the name matches exactly, the conftest is at the right level, and no plugin fixture overrides it.

Error

E       fixture 'db_session' not found
>       available fixtures: cache, capfd, ...

Steps

1. Compare the requested name with the definition character by character. Expected: typos found fast.
2. Check conftest.py placement: fixtures apply to their directory and below. Expected: the conftest covers the test file.
3. Check for shadowing: a local fixture or plugin with the same name wins. Expected: the winner identified.
4. Verify the fixture is decorated with @pytest.fixture. Expected: decoration present.
5. Re-run with --fixtures to list what pytest sees. Expected: your fixture appears.

When to use

• fixture 'x' not found at collection.
• After moving test files between directories.

When not to use

• The fixture exists but errors inside (different bug).
• Plugin fixtures missing (install the plugin).

Tool compatibility

• pytest 7/8; conftest.py discovery rules.

Variant phrasings

pytest fixture not available

Same error; check scope and naming.

fixture called directly (newer pytest)

Fixtures cannot be called directly; request them as arguments.

Why it happens

Fixture discovery is directory-scoped and name-exact. Moves, renames, and typos break it silently until collection.

Edge cases

• conftest.py in the rootdir applies everywhere; nested ones override.
• Fixture name clashes with test function arguments confuse the error.
• --import-mode changes conftest discovery; keep it consistent.

Provenance

Resolved from the public thread: https://vectle.com/posts/pst_xJ9LUm1XPs0Vt6XISyeu1g