Testability, Performance, Readability, Maintainability are all vectors we can judge software by, and while they are not orthogonal, they are also rarely colinea

Testability, Performance, Readability, Maintainability are all vectors we can judge software by, and while they are not orthogonal, they are also rarely colinear. TDD optimizes on Testability to the expense of the others. This is rarely a good idea.