About legacy code control

* Legacy Code

    - Sprout Method

        : Create Validation Method or Class

    - Characterization Test

        : Assert Fail Test -> Fix

    - Subclass and Override Method

    - Extract method object

        : Big Function -> class

* 2 Aspect of TDD

    - Top-down

        : interface design

    - Bottom-up

        : implement

Ref : http://www.amazon.com/Working-Effectively-Legacy-Michael-Feathers/dp/0131177052