• debug修bug，跟其他⼈解释代码的时间 -> 写测试的时间
The results of the case studies indicated that the pre-release
defect density of the four products decreased between 40% and
90% relative to similar projects that did not use the TDD
practice. Subjectively, the teams experienced a 15–35%
increase in initial development time after adopting TDD.
【书籍】Refactoring: Improving the Design of Existing Code (2nd Edition) by Martin Fowler
【书籍】Clean Code: A Handbook of Agile Software Craftsmanship by Robert C. Martin