Testing packages

pyngrok wraps the ngrok reverse-proxy binary and exposes it through a Python API, allowing you to programmatically open secure tunnels from public URLs to localhost.

Integrates factory_boy with pytest to register factories as fixtures, enabling dependency injection and parametrization of test object creation.

Install it if you use factory_boy and pytest together.

A pytest plugin that lets you control the execution order of your tests using markers, running specific tests first, last, or in a defined sequence.

Provides a drop-in replacement for Starlette's TestClient that uses requests instead of httpx for testing Starlette applications.

Locust Cloud is a client library for running distributed load tests against web applications via the Locust Cloud service, using gevent-based concurrency and WebSocket communication.

However, the aging maintenance status and lack of public documentation in the fact sheet suggest you should verify current support and feature stability before…

Writes HTTP Archive (HAR) files in Python with zero external dependencies, supporting single-threaded entry recording without page grouping.

A pytest plugin that enables snapshot testing—comparing test outputs against saved reference files to detect unexpected changes without manual assertion updates.

However, maintenance is dormant; verify compatibility with your pytest and Python versions before relying on it for new projects, and monitor the repository for any…

Mimesis generates realistic fake data across 47 locales—names, addresses, emails, phone numbers, financial records, and more—for populating test databases, mocking APIs, and creating fixtures without external dependencies.

pytest-retry is a pytest plugin that automatically retries failed tests, with configurable retry counts, delays, and exception filtering to help manage flaky tests in CI environments.

Not recommended as a permanent solution—use it to buy time while fixing the underlying test or environment issues.

Detects whether code is running in a test environment (pytest, doctest, or setup.py test) via runtime inspection of sys.argv and execution context.

Molecule is an Ansible testing framework for developing and testing Ansible collections, playbooks, and roles across containers, virtual machines, cloud infrastructure, and other systems reachable from Ansible.

Install it if you develop or maintain Ansible roles, playbooks, or collections and want to automate testing across diverse infrastructure targets.

Provides base classes and decorators to simplify building hybrid and dynamic test libraries for Robot Framework, handling framework API requirements automatically.

Install it if you are building a Robot Framework test library in Python and want to avoid implementing the library API boilerplate yourself.

expecttest implements inline golden tests where expected outputs are stored directly in Python source code and automatically updated when you run tests with EXPECTTEST_ACCEPT=1.

Converts terminal output with ANSI color codes to HTML or LaTeX, preserving colors and formatting for display in browsers or documents.

Install it if you need to convert ANSI-colored terminal output to HTML or LaTeX.

A pytest plugin that integrates VCR.py to record and replay HTTP interactions in tests, eliminating the need for live network calls during test runs.

However, be aware it is abandoned—no maintenance since 2019—so if you need compatibility with modern Python or pytest, or if you encounter bugs, you may need to fork…

Converts JUnit or XUnit XML test result files into a single-file HTML report for viewing test outcomes in a browser.

Wraps Xvfb, Xephyr, and Xvnc to create virtual X11 displays for headless GUI testing, automation, and screenshots on Linux systems.

A pytest plugin that sends test results to messaging platforms like Slack and Ding Talk, integrating test reporting directly into team communication channels.

Install it if your team workflow centers on these messaging platforms; skip it if you rely on email or other notification channels.

Allows you to reference pytest fixtures directly within @pytest.mark.parametrize decorators, including nested data structures and fixture attributes.

SeleniumLibrary is a Robot Framework library that provides keywords for automating web browser interactions using Selenium, enabling test automation of web applications.

Install it if you are writing Robot Framework tests that need to automate web browser interactions; it is production-ready and widely used.

inline-snapshot is a pytest plugin that lets you write snapshot tests by embedding expected values directly in your test code, then automatically updates those values when you review and approve changes.

Install it if you want snapshot testing without managing separate snapshot files, or if you prefer reviewing and approving test changes as part of code review.

CircularDict is a Python dictionary that automatically removes oldest entries when it reaches a size limit (by item count or total bytes), acting as a bounded circular buffer for memory-controlled caching and data storage.

A pytest plugin that runs tests multiple times to detect flakiness and intermittent failures without restarting pytest.

Intercepts and mocks HTTP requests made by the requests library, allowing you to test code that calls external APIs without making real network calls.

Provides standard test base classes and fixtures for validating LangChain integration implementations, particularly chat models, against a shared interface contract.

Runs a fake Snowflake database locally for testing, either by patching the Snowflake Connector in-process or via an HTTP server for non-Python clients.

RequestsLibrary wraps the Python Requests library to provide HTTP API testing keywords for Robot Framework, enabling test automation of REST endpoints without writing Python code.

However, the aging maintenance status (last release April 2024, no commits since December 2025) means you should verify compatibility with your current Robot…

Pytest plugin that profiles test execution using cProfile and generates tabular or SVG heat graph output of performance data.

Automatically downloads and installs geckodriver matching your installed Firefox version, then adds it to your system path.

pytest-celery is the official pytest plugin for Celery that enables testing of Celery applications using Docker-based environments to simulate production-like conditions, alongside traditional unit and integration testing APIs.

testtools extends Python's standard unittest framework with custom matchers, fixture management, detailed test result reporting, and cross-Python compatibility for Python 3.10+.

Install it if you're committed to unittest and want better assertions and diagnostics without migrating to pytest.

Captures C-level stdout and stderr output in Python using os.dup2, allowing you to intercept and redirect output from native libraries and compiled code that bypasses Python's standard I/O.

Install it if you work with native extensions, compiled libraries, or need output capture in Jupyter—otherwise it's not necessary.

Automatically reruns pytest (or another test runner) whenever your Python code changes, using native system file monitoring on supported platforms.

Distributes pytest test execution across multiple machines or CI workers by sharding individual test cases based on a hash of their names, enabling parallel test runs without requiring shared state.

However, do not adopt it for new projects: the package is abandoned and will not receive updates for future pytest or Python versions.

A pytest plugin that provides fixtures for safely accessing test data files organized in module-specific or shared directories, automatically copying them to temporary locations during test runs.

Testpath provides utilities for testing code that interacts with files and system commands, including filesystem assertions and mocking of command-line calls.

Provides pytest fixture factories for declaratively defining Docker-based test environments, automating container creation, teardown, and dependency resolution across test scopes.

Install it if you're writing tests that need Docker containers.

ddt multiplies a single test case across multiple datasets, letting you run parameterized tests that appear as separate test cases in your test runner.

Install it if you use unittest and want to avoid writing repetitive parameterized test methods.

Pact Python implements consumer-driven contract testing for APIs and microservices, letting you write fast unit tests that verify both client and server expectations against a shared contract instead of running brittle end-to-end integration tests.

Install it if you're testing APIs or microservices and want to shift testing left and reduce test environment complexity.

Mockito is a spying and stubbing framework for Python that lets you mock out dependencies, verify interactions, and stub side effects in unit tests.