Why Test first? help you actually write your tests not tempted to skip tests to save time you'll never come back to them skipping tests can make you slower: faster to code, slower to debug helps with the split personality you're the programmer and the tester if you've just written the code, you'll test what it does, not what it doesn't do to the programmer, "not ok" is a failure to the tester, "not ok" is a success makes you write more testable code, which is usually more modular code, which is usually better