Test-Driven Development (TDD) FAQs

Question 1

Why is writing tests after the code discouraged?

Accepted Answer

Tests written after code often just verify what was built rather than what was required. They lack the proof that the test is actually capable of catching a failure.

Question 2

How does the skill handle tests that pass immediately?

Accepted Answer

If a test passes immediately, the skill identifies this as a failure of the TDD process. You must fix the test so it fails correctly, ensuring it actually tests the intended new behavior.

Question 3

What is the 'Iron Law' of this TDD skill?

Accepted Answer

The Iron Law dictates that no production code can be written without a failing test first. If code is written before a test, it must be deleted and rewritten following the TDD cycle.

Question 4

Does this skill help with refactoring?

Accepted Answer

Yes, the 'Refactor' stage of the cycle is explicitly for cleaning up code, improving names, and removing duplication while using the green tests to ensure no behavior is broken.

Question 5

When should I use this TDD skill?

Accepted Answer

It should be used for all new features, bug fixes, refactoring, and behavior changes. It is only bypassed for throwaway prototypes or generated configuration with human approval.

Test-Driven Development (TDD)

Key Features

Use Cases

Test-Driven Development (TDD)

Key Features

Use Cases