awesome-python-testing

These software engineering rules and testing best practices might help save you time and headaches.

Mocking might seem confusing in the beginning but once you understand the basics it can be very helpful.

Learn some handy async examples and patterns for testing in Pytest.

A curated list of Behave resources, tools, and libraries for Python BDD.

Mutation testing resources: how to make better code by introducing bugs

Self-healing CLI for UI tests: runs a failing pytest + Selenium spec, repairs the drifted locator offline, re-runs it, and shows a diff before applying. Refuses to rewrite assertions, so real regressions stay visible.

A Node-based, open-source, self-improving QA agent that can exercise Python web applications externally through natural-language browser tests, persistent testing context, and self-healing tests.

Accessibility-focused DOM testing library for tdom, built with modern Python 3.14+.

Deterministic QA tool that drives every control on a web page in Chromium through Playwright and reports where the page contradicts itself, with no tests to write and no LLM.

is a front-end UI automation test framework based on BDD mode, providing a series of out-of-the-box tools and complete documentation.

is a test framework and a complete tool for browser automation. Tests can be written with code in Python, codeless using the web IDE, or both.

Merge gate for AI-written patches: runs the tests on the baseline and on the patch, mutates only the lines the patch wrote, and answers MERGE, BLOCK or INCONCLUSIVE. Missing coverage or too few killed mutants is INCONCLUSIVE, never a pass. On PyPI as

Bough is a polyglot incremental mutation tester.

makes small changes to your source code, running your test suite for each one.

Adversarial test-hardening for AI-written code, built on mutmut. A Tester agent writes tests, mutation testing names the survivors, and a Critic agent kills exactly those.

Mutation testing aimed at the checker instead of the code: it mutates a known-good input and reports which mutations a validator, linter or CI quality gate fails to reject. Zero dependencies; on PyPI as

Python mutation testing.

A CLI and Python library that scores how lexically similar N agent or LLM outputs are: exact-match rate, Jaccard token overlap, divergence point, and a composite convergence score over any list of runs. An eval primitive for measuring reproducibility and fan-out collapse. Zero deps.

A comprehensive fuzzing tool designed specifically for testing Model Context Protocol (MCP) servers. It supports both tool argument fuzzing and protocol type fuzzing across multiple transport protocols.

Records a Python agent's calls to its model provider from outside the process, then serves the recording back so the same run happens again with the provider unreachable and no key. Turns a failed session into a regression test. Apache-2.0.

is a helper for mock/fake web requests in python aiohttp package.

record & replay mock server.

Zero-dependency in-memory virtual filesystem with hard quotas. Provides an explicit, isolated instance instead of patching global state.

Powerful test doubles framework for Python.

is a testing library for Python that makes it easy to create mocks, stubs and fakes.

Travel through time by mocking the datetime module.

work by comparing the test results to a golden master.

a pytest plugin that boosts efficiency when writing tests by generating code with the expected values and simplifies snapshot tests with pytest.

A framework-agnostic library for testing ASGI web applications.

(Python standard library) The doctest module searches for pieces of text that look like interactive Python sessions, and then executes those sessions to verify that they work exactly as shown.

Fast python test runner, compatible with a subset of pytest.

Maelstrom is a fast Rust and Python test runner that runs every test in its own container. Tests are either run locally or distributed to a clustered job runner.

Doctest for Markdown in any language: runs the console sessions and code blocks in your README/docs, verifies their output still matches, and rewrites them in place with

The successor to

is a coverage-guided Python fuzzing engine. It supports fuzzing of Python code, but also native extensions written for CPython.

Adaptive fuzzing of Hypothesis tests.

is an advanced Quickcheck style property based testing library.

An extensions for Hypothesis that provides fully automatic testing for type hinted functions.

Add the power of solver-based symbolic execution to your Hypothesis tests with CrossHair.

Instead of writing manually the Hypothesis search strategies for a function,