---
id: lit
version: "18.1.8"
license: Apache-2.0 with LLVM exception
license_treatment: permissive
maintenance: dormant
---

# lit — A Software Testing Tool

License: permissive · Maintenance: dormant · Downloads: 3.4M/mo

## What it is and what it does

lit is a lightweight, portable test runner originally designed for LLVM and Clang test suites. It discovers tests, executes them in parallel, and provides a summary of results with clear failure reporting. The package has no runtime dependencies, making it simple to install and deploy.

lit is primarily used by LLVM developers and projects that adopt LLVM's test infrastructure. It supports multiple test formats and flexible test discovery, allowing projects to define custom test runners. The tool is designed for simplicity and portability across operating systems, though its active development has stalled—the last release was 780 days ago and maintenance status is dormant.

Use it for:

- Run LLVM and Clang test suites locally or in CI pipelines with parallel execution.
- Execute custom test suites that follow LLVM's test format conventions in projects that adopt lit.
- Integrate lit into build systems for projects that depend on LLVM toolchain testing.
- Discover and run tests across multiple directories with flexible, configurable test discovery rules.

## Worth the install?

AI-flagged interpretation of the facts above — verify before relying.

lit is a portable test runner for executing LLVM and Clang style test suites, summarizing results, and reporting failures with parallel execution support.

Yes, if you are working with LLVM, Clang, or a project that already uses lit for testing. The package is stable, has no dependencies, and installs easily. However, do not install expecting active maintenance or new features—development is dormant. For new test infrastructure projects, consider whether lit's LLVM-centric design fits your needs or whether a more actively maintained alternative would be safer.

## Install

pip install lit
uv add lit
poetry add lit

## Installing lit

Before you install: Low install friction with no runtime dependencies. Maintenance status is dormant—780 days since last release—so expect no active bug fixes or feature development, though the package remains functional for its core use case.

License in practice: Licensed under Apache-2.0 with LLVM exception (permissive). Safe for commercial and private use with minimal attribution requirements.

Quickstart:

pip install lit
lit --path /path/to/llvm/build/bin /path/to/test/suite

Requires LLVM utilities (not, FileCheck) to be built and available in PATH for full test suite execution.

Verify before relying:

- Whether lit works with modern Python versions beyond what the fact sheet specifies.
- Current state of LLVM integration and whether the package remains compatible with recent LLVM releases.
- Whether parallel test execution performance scales meaningfully for large test suites.

## Package facts

- License: Apache-2.0 with LLVM exception (permissive)
- Python support: unspecified
- Install friction: low
- Maintenance: dormant
- Downloads: 3.4M/month (top 5,000 on PyPI)
- Known vulnerabilities: none known

## Tags

llvm test runner, clang test suite execution, parallel test framework, portable test harness, llvm lit testing tool, test discovery and execution, c++ test automation, llvm-toolchain, test-runner, dormant-maintenance

[View on SkillFed](https://skillfed.io/packages/lit) · [View on PyPI](https://pypi.org/project/lit/)