Modern C++ Programming with Test-Driven Development

2.3 Getting Started

A common misconception of TDD is that you first define ​all​ the tests before building an implementation. Instead, you focus on one test at a time and incrementally consider the next behavior to drive into the system from there.

As a general approach to TDD, you seek to implement the next simplest rule in turn. (For a more specific, formalized approach to TDD, refer to the TPP [Section 10.4, ​The Transformation Priority Premise​].) What useful behavior will require the most straightforward, smallest increment of code to implement?

With that in mind, where do we start with test-driving the Soundex solution? Let’s quickly speculate as to what implementing each rule might entail.

Soundex rule #3 appears most involved. Rule #4, ...