{"id":28189,"library":"slipcover","title":"SlipCover","description":"Near zero-overhead Python code coverage tool that uses bytecode instrumentation to measure line and branch coverage with minimal performance impact. Current version 1.0.18, supports Python 3.8 to 3.14, maintained actively on GitHub.","status":"active","version":"1.0.18","language":"python","source_language":"en","source_url":"https://github.com/plasma-umass/slipcover","tags":["coverage","testing","bytecode-instrumentation","performance"],"install":[{"cmd":"pip install slipcover","lang":"bash","label":"Install from PyPI"}],"dependencies":[{"reason":"SlipCover's output XML and JSON are compatible with coverage.py's report formats","package":"coverage","optional":true},{"reason":"SlipCover supports parallel test execution with pytest-xdist since v1.0.18","package":"pytest-xdist","optional":true}],"imports":[{"note":"SlipCover is a class, direct import of the package won't give you the coverage runner","wrong":"import slipcover","symbol":"SlipCover","correct":"from slipcover import SlipCover"}],"quickstart":{"code":"from slipcover import SlipCover\n\nsc = SlipCover()\nsc.start()\n# run code to be measured\nsc.stop()\nprint(sc.report())","lang":"python","description":"Basic usage: start/stop coverage and print summary"},"warnings":[{"fix":"Use Python 3.8 to 3.14.","message":"Python 3.8 is required minimum, Python 3.15+ is not supported (requires_python: <3.15,>=3.8).","severity":"breaking","affected_versions":"<3.8 or >=3.15"},{"fix":"pip install --upgrade slipcover>=1.0.12","message":"SlipCover uses a C extension (`probe.abi3.so`). On macOS >14.2, wheels may cause dlopen errors like 'bad bind opcode 0x00'. Upgrade to >=1.0.12.","severity":"gotcha","affected_versions":"<1.0.12 on macOS >14.2"},{"fix":"Upgrade to >=1.0.18 or use separate `--source` and `--omit` invocations.","message":"The `--omit` flag does not work with `--source` prior to v1.0.18. Combining them may omit nothing.","severity":"gotcha","affected_versions":"<1.0.18"}],"env_vars":null,"last_verified":"2026-05-09T00:00:00.000Z","next_check":"2026-08-07T00:00:00.000Z","problems":[{"fix":"Upgrade to slipcover>=1.0.11","cause":"Bug in SlipCover versions <1.0.11 on Python 3.12+ when parsing bytecode ranges.","error":"ValueError: line ..., column ...-... is not a valid range"},{"fix":"pip install --upgrade slipcover>=1.0.12","cause":"Incorrectly built wheel for macOS >14.2 in versions <1.0.12.","error":"dlopen(/opt/homebrew/lib/python3.11/site-packages/slipcover/probe.abi3.so, 0x0002): bad bind opcode 0x00"}],"ecosystem":"pypi","meta_description":null,"install_score":null,"install_tag":null,"quickstart_score":null,"quickstart_tag":null}