gistfile1.txt

    * Levels of tests
          o unit test
          o integration test
          o system test
          o acceptance test
    * Why test? (acceptance test / system test)
          o verify correctness: bugs always exist (but we can keep them small and easier to solve)
          o save manually verification time
    * Why unit test?
          o help find root of bugs (save debugging time)
          o examples for tracing codes
    * Why test first?
          o help design (you never know how to design easy-to-use functions until you use them)
          o prevent over-design
          o prevent over-test
          o make refactoring easily and refactoring is necessary
          o save more time of manual verification
    * Why refactoring?
          o prevent potential bugs
          o easier to read / reuse / add new functions
    * When it's time to write more unit tests?
          o print states
          o run debugger (too many states to print)
          o don't know where the bug is
    * If TDD is so good, why it's not popular?
          o It's hard to learn: need at least twice time to learn skills (test patterns / design patterns / refactoring patterns)
          o it doesn't fit current development flow in big companies: development teams think QA help them test (but that's not unit tests) and refactoring is not allowed since it causes conflics when merging codes between development teams and QA's branches)