The Scientific Method

It's funny how similar TDD is to the Scientific Method. In fact, I think that they're pretty much the same flow.


Scientific Method Flow:




TDD Flow:

A test is NOT a Unit Test when...

• It talks to a database


• It communicates across a network


• It touches the file system


• You have to do special things to your environment (such as editing config files) to run it

Tests that do these things are integration tests, not unit tests. [Shore & Warden 2007]

Overview of Test-Driven Development

What is Test-Driven Development?

"Test-driven design (TDD) is a development technique where you must first write a test that fails before you write new functional code.[...]TDD does not replace traditional testing, instead it defines a proven way to ensure effective unit testing. A side effect of TDD is that the resulting tests are working examples for invoking the code, thereby providing a working specification for the code. - Ambler"

Scott Ambler has a thorough article on Test-Driven Development that explains the methodology. If you're curious on the subject, I recommend reading it:

http://www.agiledata.org/essays/tdd.html