10 best Python Mock libraries in 2025

Mock objects make it possible to write automated tests for code that depends on external services or resources. The most common scenario is when a web application depends on some kind of database. Mocking the database allows you to write tests that check that code that uses the database is operating correctly without actually performing any database operations (which may well be slow or impossible). In this kit, we will discuss the top 8 Python Mock Open Source libraries that you can use in your testing project. moto - easily mock out tests based on AWS infrastructure; responses - A utility for mocking out the Python Requests library; vcrpy - Automatically mock your HTTP interactions.