Primer - How to Write Testable Code

Before you start writing unit tests and integration tests and automating it all in the continuous integration environment, you have to make sure that the technical design principles you apply make your code easily testable. If you can't cleanly test your code your tests will not have any value as bugs will be easy to miss or tests would end up being to fragile. Whether you apply test driven development (i.e. write tests first) or not, the complexity of your technical design will ultimately affect the complexity of your tests.