测试驱动开发（英语：Test-driven development，缩写为TDD）是一种软件开发过程中的应用方法，由极限编程中倡导，以其倡导先写测试进程，然后编码实现其功能得名。测试驱动开发始于20世纪90年代。测试驱动开发的目的是取得快速反馈并使用“illustrate the main line”方法来构建进程。

测试驱动开发是戴两顶帽子思考的开发方式：先戴上实现功能的帽子，在测试的辅助下，快速实现其功能；再戴上重构的帽子，在测试的保护下，通过去除冗余的代码，提高代码质量。测试驱动着整个开发过程：首先，驱动代码的设计和功能的实现；其后，驱动代码的再设计和重构。

Test-driven development (TDD) is a software development process that relies on the repetition of a very short development cycle: first an (initially failing) automated test case is written that defines a desired improvement or new function. Then, the minimum amount of code is written to pass that test, and finally one refactors the new code to acceptable standards. Kent Beck, who is credited with having developed or 'rediscovered' the technique, stated in 2003 that TDD encourages simple designs and inspires confidence.