Any fool can write code that a computer can understand. Good programmers write code that humans can understand. - Kent Beck

Often you'll see the same three or four data items together in lots of places: fields in a couple of classes, parameters in many method signatures. Bunches of data that hang around together really ought to be made into their own object.

The business changes. The technology changes. The team changes. The team members change. The problem isn't change, per se, because change is going to happen; the problem, rather, is the inability to cope with change when it comes.

The key is to test the areas that you are most worried about going wrong. That way you get the most benefit for your testing effort. It is better to write and run incomplete tests than not to run complete tests