pytest-fail-slow

0.6.0 verified Mon Apr 27 auth: no python

A pytest plugin that fails tests exceeding a configurable duration. v0.6.0 supports both marker-level and command-line slow time thresholds; actively maintained.

pip install pytest-fail-slow

Common errors

error ImportError: cannot import name 'fail_slow' from 'pytest_fail_slow' ↓

cause Older versions may not expose the decorator; or package not installed.

fix

Install pytest-fail-slow >=0.5.0: pip install --upgrade pytest-fail-slow

error TypeError: fail_slow() missing 1 required positional argument: 'seconds' ↓

cause Decorator called without parentheses or argument.

fix

Use @fail_slow(2.0) not @fail_slow

error pytest: error: unrecognized arguments: --fail-slow ↓

cause Using deprecated flag; plugin expects new flag.

fix

Use --fail-slow-seconds <value> instead.

Warnings

gotcha The @fail_slow decorator must be applied after @pytest.mark.slow or similar markers; order matters because the decorator reads the test's current marker info. ↓

fix Place @fail_slow closest to the function, above other custom decorators.

gotcha The plugin only works with pytest's default runner; custom runners may silently ignore the fail_slow marker. ↓

fix Use the default pytest runner.

deprecated The CLI option --fail-slow is deprecated in v0.6.0; use --fail-slow-seconds instead. ↓

fix Use `--fail-slow-seconds <seconds>` from command line.

Imports

fail_slow
```
from pytest_fail_slow import fail_slow
```
decorator used to mark individual tests

Quickstart

Enable plugin and use @fail_slow decorator to set per-test maximum duration in seconds.

# conftest.py
pytest_plugins = ['pytest_fail_slow']
# then in test
import pytest
from pytest_fail_slow import fail_slow

@fail_slow(0.5)
def test_fast_enough():
    import time
    time.sleep(0.1)
    assert True