lit

library23.1.0pypypi✓ verified 24d ago

lit (LLVM Integrated Tester) is a portable command-line tool for executing LLVM and Clang style test suites, summarizing their results, and providing indication of failures. It is designed to be lightweight and flexible, supporting parallel test execution and various test formats. The current version is 18.1.8 and is actively maintained as part of the LLVM project.

testing

pip install lit

package ↗homepage ↗

INSTALL

IMPORT

SIG · LIT

lit

testingpythonv23.1.0

Install

1.6s avg

Import

—

Disk

17MB

Pass rate

10/ 10

Env Coverage10 / 10

glibc

3.9–3.13

musl

3.9–3.13

Install & Compatibility

Where this runs

tested against v23.1.0 · pip install

no network on importno background threads

Install × environment matrix

Each cell = how many times install + import succeeded across repeated harness runs. Partial = flaky.
glibc = Debian/Ubuntu slim · musl = Alpine Linux

musl

py 3.10–3.95 runs

installs and imports cleanly · install 0.0s · import 0.000s · 18.5MB

glibc

py 3.10–3.95 runs

installs and imports cleanly · install 1.6s · import 0.000s · 19MB

17MB installed

● package 17MB

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

lit_config

✓ This is a global object implicitly available within lit.cfg.py / lit.site.cfg.py files.

lit is primarily a command-line tool that executes Python configuration files (lit.cfg.py). Direct import statements of 'lit' as a Python library for programmatic API calls are uncommon in application code. Configuration relies on predefined global objects like `lit_config` and `config` within these specific config files.

config

✓ This is a global object implicitly available within lit.cfg.py / lit.site.cfg.py files.

Similar to `lit_config`, the `config` object is exposed globally within `lit`'s Python configuration files (`lit.cfg.py`), allowing users to define test suite behavior without explicit Python imports from the 'lit' package itself.

This quickstart demonstrates how to set up a basic `lit` test suite. It involves creating a `lit.cfg.py` configuration file that `lit` uses to understand how to find and run tests, and a simple test file with `RUN` and `CHECK` directives. `lit` is then invoked from the command line against the test directory.

# 1. Create a test directory and a lit configuration file: # my_project/ # ├── lit.cfg.py # └── tests/ # └── my_test.txt # --- lit.cfg.py --- # This file is executed by lit to configure the test suite. # Define standard test formats. import lit.formats config.name = 'MyProject' config.test_format = lit.formats.ShTest(not_tool='/usr/bin/not') config.suffixes = ['.txt'] # Add an optional path to tools if they are not in PATH # config.substitutions = [('%my_tool', '/path/to/my_tool')] # --- tests/my_test.txt --- # RUN: echo "Hello, lit!" | FileCheck %s # CHECK: Hello, lit! # --- Run lit from the project root --- # In your terminal: # cd my_project # lit tests/

lit --version

Debug

Known issues

gotchalit is primarily a command-line testing tool. While written in Python, its main usage involves running the `lit` executable and configuring test suites via `lit.cfg.py` or `lit.site.cfg.py` files, rather than through direct Python API imports for general application logic. The Python files define test execution logic, not library functions to be called.

fix

Focus on command-line invocation and Python configuration files (`lit.cfg.py`) for defining test behavior, rather than looking for a traditional Python API to import and call.

affects: All versions

gotchaThe `lit` command expects a `lit.cfg.py` or `lit.site.cfg.py` file to be present in the root of each test suite or discovered by searching upwards from the input path. Without these configuration files, `lit` cannot properly discover or execute tests.

fix

Ensure that your test directory hierarchy includes the necessary `lit.cfg.py` (or `lit.site.cfg.py`) files to define test suite parameters like `config.test_format` and `config.suffixes`.

affects: All versions

gotchaThe `lit` tool, especially for certain test formats, often relies on external LLVM utilities like `FileCheck` and `not`. If these are not available in the system's PATH, or explicitly configured in `lit.cfg.py`, tests that use them will fail.

fix

Ensure that required LLVM tools (like `FileCheck` and `not`) are installed and accessible in your system's PATH, or specify their full paths using `config.substitutions` or directly in `config.test_format` (e.g., `not_tool='/usr/bin/not'`) within your `lit.cfg.py` file.

affects: All versions

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Version history

23.1.0latest on PyPI · released Aug 25, 2026

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Dependencies

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Agent activity

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Resources

packagehttps://pypi.org/project/lit/ ↗

homepagehttp://llvm.org ↗