Characterization test

In computer programming, a characterization test is a mean to describe (characterize) the actual comportment of an existing piece of software.

The goal of Charaterization Tests is to allow verifying that the modifications brought to the software did not modify its behavior. They enables extending and refactoring code that does not have unit test.

Unlike Regression Tests, to which they are very close, they do not verify the correct behavior of the code, but the behavior that was observed when they have been written.

This term was coined by Michael Feathers in its book "Working effectively with legacy code".