Test-driven development

Test-driven development (TDD) is a philosophy and process for integrating comprehensive testing into the software development process at the earliest stage possible. The idea behind this approach is to begin with a set of fully tested individual components and continue testing as these components are integrated into a functional system. By using this methodology, the likelihood of significant bugs remaining in the code is drastically reduced.

To make the development process test-driven, you first write a test for a piece of functionality that does not yet exist in the system and then run the test. The test should fail, perhaps by not even compiling successfully if a function being called does not yet exist. You then implement the function the test is attempting to execute, which should allow the test to pass. The set of tests should verify as fully as possible that the implemented system code is performing correctly.

While fairly simple in concept, there...