Unit Tests

Unit tests are a category of tests known as white box tests. The entire software system can be looked at two ways. The end consumer of the component sees a black box because they are not exposed to the source code, database definitions, and other processes that drive the application. Instead, they are aware of interactions (most often directly through the user interface) that go into a black box as well as results that come out of that black box. This is the realm of integration, QA, and automated UI tests.

White box tests would be better referred to as clear box tests because they imply exposure to the inner workings of the system. Unit tests require a fundamental knowledge of what’s happening at the source code level. Integration tests require knowledge of the APIs and boundaries between systems. White box tests ensure the inner workings of a black box are functioning correctly.