A run that dies during collection

Showing pytest 9.1.1 pytest 9.1.0 pytest 9.0.3 pytest 9.0.2 pytest 9.0.1 pytest 9.0.0 pytest 8.4.2 pytest 8.4.1 pytest 8.4.0 pytest 8.3.5 pytest 8.3.4 pytest 8.3.3 pytest 8.3.2 pytest 8.3.1 pytest 8.3.0 pytest 8.2.2 pytest 8.2.1 pytest 8.2.0 pytest 8.1.2 pytest 8.1.1 pytest 8.0.2 pytest 8.0.1 pytest 8.0.0 pytest 7.4.4 pytest 7.4.3 pytest 7.4.2 pytest 7.4.1 pytest 7.4.0 pytest 7.3.2 pytest 7.3.1 pytest 7.3.0 pytest 7.2.2 pytest 7.2.1 pytest 7.2.0 pytest 7.1.3 pytest 7.1.2 pytest 7.1.1 pytest 7.1.0 pytest 7.0.1 pytest 7.0.0 pytest 6.2.5 pytest 6.2.4 pytest 6.2.3 pytest 6.2.2 pytest 6.2.1 pytest 6.2.0 pytest 6.1.2 pytest 6.1.1 pytest 6.1.0 pytest 6.0.2 pytest 6.0.1 pytest 6.0.0

pytest 8.1.1 - 9.1.1 - What pytest does when a hook implementation raises.

These 20 releases produced an identical flow, so they share one page. Identical as far as this scenario can measure - a scenario exercising more hooks may tell them apart.

The conftest.py here raises from pytest_collection_modifyitems. Nothing catches it, so pytest abandons the session and reports an internal error.

No test ever runs, so the whole run-test phase is missing from this diagram - which is the point. It shows how little of a session happens when a hook implementation fails early, and which hooks still get their chance to clean up.

How this was produced

• Source: scenarios/internal-error/ - the project this diagram was traced from
• Invocation: pytest . -q
• Traced against: pytest 9.1.1, pluggy 1.6.0, Python 3.12.3
• Covers: 20 releases - pytest 8.1.1 - 9.1.1, which produced an identical flow
• Observed: 116 hook calls, 22 distinct hooks

The project is conftest.py, test_never_runs.py. Browse it in the repository rather than inline here - scenarios grow directory trees, and GitHub renders them better than a collapsed block can.

The whole run

Phases left to right, steps top to bottom. Colour says which phase a hook belongs to; how dark a step is says how often it was called. Click a column heading to jump to that phase in full detail, or any hook to open its pytest documentation. Why it looks like this

Startup and configuration

Everything before collection begins: initial conftests are loaded, plugins register, and the session is configured.

Collection

Finding tests. Note that pytest_make_collect_report recurses - directories contain directories contain files.

Session finish

Summary reporting and teardown of the session.

Every hook observed

Hook	Calls	Semantics	Implemented by, in call order
pytest_cmdline_main	1	firstresult	_pytest.setupplan [tryfirst] _pytest.setuponly [tryfirst] _pytest.mark [tryfirst] _pytest.helpconfig _pytest.fixtures _pytest.main 1
pytest_collect_directory	1	firstresult	_pytest.python _pytest.main
pytest_collect_file	4		_pytest.doctest _pytest.python
pytest_collection	1	firstresult	_pytest.logging.LoggingPlugin (logging-plugin) [wrapper, tryfirst] _pytest.warnings [wrapper, tryfirst] _pytest.config.Config (pytestconfig) [wrapper] _pytest.terminal.TerminalReporter _pytest.assertion _pytest.main
pytest_collection_finish	1		_pytest.fixtures.FixtureManager (funcmanage) _pytest.terminal.TerminalReporter 2
pytest_collection_modifyitems	1		_pytest.fixtures.FixtureManager (funcmanage) conftest.py _pytest.main _pytest.mark
pytest_collectreport	3		_pytest.main.Session.pytest_runtest_logreport (session) [tryfirst] _pytest.terminal.TerminalReporter
pytest_collectstart	3		_pytest.main.Session [tryfirst]
pytest_configure	1	historic	_pytest.subtests _pytest.faulthandler _pytest.warnings _pytest.threadexception _pytest.unraisableexception _pytest.junitxml _pytest.assertion _pytest.tmpdir _pytest.legacypath _pytest.skipping _pytest.unittest _pytest.debugging _pytest.terminal _pytest.python _pytest.mark _pytest.config.PytestPluginManager (<anonymous>) _pytest.pastebin [trylast] _pytest.logging [trylast] 3
pytest_generate_tests	1		_pytest.fixtures.FixtureManager (funcmanage) _pytest.python
pytest_ignore_collect	5	firstresult	_pytest.main
pytest_internalerror	1		_pytest.capture.CaptureManager [tryfirst] _pytest.terminal.TerminalReporter
pytest_itemcollected	1		-
pytest_load_initial_conftests	1		_pytest.warnings [wrapper] _pytest.capture [wrapper] _pytest.legacypath [tryfirst] _pytest.config.Config (pytestconfig) [trylast] 4
pytest_make_collect_report	3	firstresult	_pytest.fixtures.FixtureManager (funcmanage) [wrapper] _pytest.capture.CaptureManager [wrapper] _pytest.runner 5
pytest_plugin_registered	80	historic	_pytest.legacypath _pytest.terminal.TerminalReporter _pytest.fixtures.FixtureManager (funcmanage)
pytest_pycollect_makeitem	3	firstresult	_pytest.unittest _pytest.python [trylast]
pytest_pycollect_makemodule	1	firstresult	_pytest.python
pytest_report_collectionfinish	1		-
pytest_sessionfinish	1		_pytest.logging.LoggingPlugin (logging-plugin) [wrapper, tryfirst] _pytest.terminal.TerminalReporter [wrapper] _pytest.warnings [wrapper] _pytest.assertion _pytest.tmpdir _pytest.runner
pytest_sessionstart	1		_pytest.logging.LoggingPlugin (logging-plugin) [wrapper, tryfirst] _pytest.fixtures _pytest.runner _pytest.terminal.TerminalReporter [trylast]
pytest_unconfigure	1		_pytest.logging.LoggingPlugin (logging-plugin) _pytest.terminal.TerminalReporter _pytest.faulthandler _pytest.unraisableexception _pytest.doctest _pytest.junitxml _pytest.pastebin _pytest.mark 6

6 of these changed implementer somewhere in pytest 8.1.1 - 9.1.1 without changing the flow - pytest moves implementations between its own plugins. The table shows the newest; what changed along the way is below.

---

1. 8.2.0 gained _pytest.fixtures and lost _pytest.python ↩

2. 9.1.0 gained _pytest.fixtures.FixtureManager (funcmanage) ↩

3. 8.4.0 gained _pytest.threadexception, _pytest.unraisableexception; 8.4.1 gained _pytest.unittest; 9.0.0 gained _pytest.subtests; 9.1.0 gained _pytest.assertion ↩

4. 8.4.0 lost _pytest.python_path ↩

5. 9.1.0 gained _pytest.fixtures.FixtureManager (funcmanage) ↩

6. 8.4.0 lost _pytest.python_path; 9.1.0 gained _pytest.unraisableexception ↩