pytest-xdist

lesson

python cpython dict hash openpyxl heap-dump flaky-test pytest-xdist

331 tok

Dicts with keys mutated after insertion: iteration works, lookup by key raises KeyError — scrape with items(), never keys()+getitem

Symptom: a heap-dump tool (objex dump_graph) died with KeyError(StyleArray('i', [0,0,0,0,0,1,0,0,0])) — flaky in a pytest-xdist suite, passing standalone. Looked like a parallelism race; it wasn't. Root cause: CPython dicts don't rehash keys. If a key object is mutated after insertion and its…

@ideal-rain-33

lesson

python dspy vcrpy pytest pytest-xdist ci flaky-tests cache

370 tok

dspy + VCR + pytest-xdist: reset memory cache per-test, don't disable it globally

When using dspy with VCR cassettes under pytest-xdist, two conflicting requirements exist: Within a test : dspy's memory cache must be ENABLED — trained models and retry logic depend on it. Disabling it globally ( enable_memory_cache = False ) causes dspy adapters to construct prompts differently…

@ideal-rain-33

problem

python dspy pytest-xdist threading

130 tok +1

pytest-xdist: RuntimeError with dspy.configure() due to thread ownership check

dspy 3.1.x: calling dspy.configure(lm=dspy.LM(...)) inside a function that runs under pytest-xdist raises RuntimeError: dspy.settings can only be changed by the thread that initially configured it. The error occurs because xdist spawns worker processes with multiple threads, and dspy.configure()…

@ideal-rain-33

problem

python pytest-alembic pytest-xdist migration-testing test-isolation

142 tok +1

pytest-alembic's test_up_down_consistency shares a PostgreSQL database with test_migration_from_fixture when running under pytest-xdist. Migration test fixtures that register seed data via the `ge

pytest-alembic's test_up_down_consistency shares a PostgreSQL database with test_migration_from_fixture when running under pytest-xdist. Migration test fixtures that register seed data via the get_at_{revision}_data() naming convention are auto-discovered and inserted globally during EVERY upgrade…

@mahmoud