Today,got so much by reviewing TDD.
some sentences r so good.eg:

Rather than apply minutes of suspect reasoning, we can just ask the computer
by making the change and running the tests. In teaching TDD I see this situation
all the time—excellent programmers spending 5-10 minutes reasoning about a
question that can be answered by the computer in 15 seconds.Without the tests you
have no choice, you have to reason.