Unit testing became prevalent with Java's JUnit, but C#'s NUnit has really pushed it to new areas.

The articles on this page explore various unit testing concepts, and sometimes help evolve unit testing to the next level of Test Driven Desgin (TDD).

Note: Once you embrace TDD your code magically starts working better and you will see large shortcomings in your old code. It is a big effort to fully understand TDD, but it is worth every bit of that effort.