Test-First Development

The test is an executable specification: to write it, you decide the inputs, the result, and what the operation must do before any code exists. That helps you understand the contract before you implement it.

The tests are written against the ADT’s contract, not against an implementation. That is all a test needs.

TDD works in a smaller loop. You write one test, implement just enough code to make it pass, then write the next test, and so on. The code and its tests grow together.