Testing First (TDD)

Test as you write the code.
Write automated tests.

Why and when does this make sense?

• When testing in small steps most errors can be quickly traced back to their origin
• Testing manually is boring - awareness quickly decreases and errors slip in unrecognized
• Testing manually is slow compared to automated tests
• Automated tests give confidence while refactoring

(Also components of electronic devices are typically tested before they are assembled to more complex units.)

Books and Articles

• Among the most recommendable surely is the classic from Kent Beck:
  Test Driven Development: By Example, 2002, ISBN 0-321-14653-0
• And of course, as he is another big TDD proponent:
  linking to Martin Fowler's entry page for TDD is a "must" here

Quite surely, there are many good readings on TDD at all levels and therefore it is not understandable to me why - and this is not made up, it actually happened to a close friend - a software developer was forced by the project leader to code for weeks and months without being allowed to do even a single test of any line of code she had written! You can bet: you would have seen me running out of this shop yelling loud the second or third day ... :-)