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9.1.1: nested conftest fixtures are not found when file arguments interleave a nested directory with its parent #14971
Description
Passing test files on the command line in the order nested/a.py parent/top.py nested/b.py makes fixtures defined in nested/conftest.py invisible to the last file on pytest 9.1.1. The same command passes on pytest 8.4.2, and passes on 9.1.1 when the two nested files are adjacent or when the directory is given instead of the files.
Minimal reproduction (Python 3.10.19, macOS, no plugins beyond the defaults):
tests/conftest.py
import pytest
@pytest.fixture
def root_fixture():
return "root"
tests/services/conftest.py
import pytest
@pytest.fixture
def nested_fixture():
return "nested"
tests/services/test_a.py
def test_a(nested_fixture):
assert nested_fixture == "nested"
tests/services/test_b.py
def test_b(nested_fixture):
assert nested_fixture == "nested"
tests/test_top.py
def test_top(root_fixture):
assert root_fixture == "root"
$ python -m pytest tests/services/test_a.py tests/test_top.py tests/services/test_b.py -q -p no:cacheprovider
pytest 9.1.1 -> 2 passed, 1 error (ERROR at setup of test_b: fixture 'nested_fixture' not found)
pytest 8.4.2 -> 3 passed
What we traced (please treat as a pointer, not a diagnosis): with a bare file argument directly under an ancestor directory, Session.collect sets handle_dupes=False, so _collect_one_node bypasses its cache and re-collects tests/services, producing a second Directory node instance for the same path. Since 9.x matches fixture visibility by node identity in FixtureManager._matchfactories rather than by nodeid prefix, fixtures registered on the first tests/services instance are invisible to items collected under the second one. Two real projects hit this from developers running a hand-picked file list; pytest tests/ is unaffected.
Activity
test: every fixture lives in the root conftests and a gate test fails…
kokhlo commentedon Sep 7, 2026
Hi! I can take this one.
Trace confirms the pointer:
Session.collectpasseshandle_dupes=Falsefor bare file args, so_collect_one_nodere-collectstests/servicesand creates a secondDirectorynode for the same path.FixtureManager._matchfactoriesthen matches by node identity (nodeid equality of the collected parent chain), so fixtures defined innested/conftest.pyand registered under the firstDirectoryinstance are invisible to items collected under the second one.Plan:
nested/a.py parent/top.py nested/b.py).handle_dupes=Falsepath reuse the existing cachedDirectorynode when it already exists, or match fixtures by nodeid prefix in_matchfactoriesinstead of node identity.I'll follow the contributor guidelines and aim to keep the diff minimal.
kokhlo commentedon Sep 7, 2026
Update after verification — retracting my claim, this is already fixed on main.
Verified on a clean venv: the repro fails on 9.1.1 exactly as reported (
2 passed, 1 error, fixture lost on the interleaved run), but passes 3/3 on current main (built from source).The fix is #14635 (commit
fc8f56bd2, merged 2026-07-22):_collect_one_nodenow reconciles re-collected Directory children with cached ones so fixture registration keyed by node identity stays valid — precisely the mechanism traced in this report. It landed after the 9.1.1 release (2026-06-19), which is why the reporter still sees it; there is no 9.1.x maintenance branch, so it ships with 9.2.0.Sorry for the noise on the claim — hope the verification still saves a triage round. Thanks for the excellent root-cause tracing, it made this a five-minute check.
RonnyPfannschmidt commentedon Sep 11, 2026
#14968 is the backport
rennf93 commentedon Sep 11, 2026
Tyvm @RonnyPfannschmidt @kokhlo !
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