There are many unit testing tools out there, with the xUnit family holding a predominant place. In the Java world, JUnit is the de facto standard, although TestNG is another popular Java unit testing framework with a number of innovative features. For C# applications, the NUnit testing framework proposes similar functionalities to those provided by JUnit, as does Test::Unit for Ruby. For C/C+ +, there is CppUnit, and PHP developers can use PHPUnit. And this is not an exhaustive list!