在计算机编程中，单元测试（英语：Unit Testing）又称为模块测试, 是针对进程模块（软件设计的最小单位）来进行正确性检验的测试工作。进程单元是应用的最小可测试部件。在过程化编程中，一个单元就是单个进程、函数、过程等；对于面向对象编程，最小单元就是方法，包括基类（超类）、抽象类、或者派生类（子类）中的方法。

通常来说，程序员每修改一次程序就会进行最少一次单元测试，在编写程序的过程中前后很可能要进行多次单元测试，以证实程序达到软件规格书要求的工作目标，没有进程错误；虽然单元测试不是什幺必须的，但也不坏，这牵涉到专案管理的政策决定。

In computer programming, unit testing is a software testing method by which individual units of source code, sets of one or more computer program modules together with associated control data, usage procedures, and operating procedures, are tested to determine whether they are fit for use. Intuitively, one can view a unit as the smallest testable part of an application. In procedural programming, a unit could be an entire module, but it is more commonly an individual function or procedure. In object-oriented programming, a unit is often an entire interface, such as a class, but could be an individual method. Unit tests are short code fragments created by programmers or occasionally by white box testers during the development process. It forms the basis for component testing.