Modern C++ Programming with Test-Driven Development

2.8 Test-Driving vs. Testing

We need to test-drive more of the consonant conversion logic in order to generalize our solution. Should we add an assertion to ReplacesConsonantsWithAppropriateDigits, or should we create an additional test?

The rule of thumb for TDD is one assert per test (see Section 7.3, ​One Assert per Test​ for more information on this guideline). It’s a good idea that promotes focusing on the behavior of the tests, instead of centering tests around functions. We will follow this rule most of the time.

An assertion that represents encoding a second consonant doesn’t seem like distinct behavior. Were we to create a new test, how would we name it? ReplacesBWith1, ReplacesCWith2, and so on...yuk!

We make the rare choice of adding ...