Even if we design for testability, the likelihood that we can write the tests easily and naturally without modifying the production code is low. When tests are written first, however, the design of the system is inherently testable.

When there is any way to test without a database, test without the database!

When it is not important for something to be seen in the test method, it is important that it NOT be seen in the test method!

Keep the bar green to keep the code clean.

A job worth doing is worth doing well.

The value of tests lies in their growth and evolution over time, not in the initial spurt, which in terms of the big picture is insignificant.

Unit tests: Fast, fast, fast. Run them before every check in.
Functional tests: Slower. Run them overnight or on weekends.

You need them both.

Complexity kills. It sucks the life out of developers, it makes products difficult to plan, build and test, it introduces security challenges and it causes end-user and administrator frustration.

What's more important to you? Testability or encapsulation? There's nothing special about encapsulation. I'll sacrifice it for testability any day of the week and twice on Sundays.

One of the first steps in increasing your agility is learning to listen to your code, and more importantly - to listen to your tests.