Test-Driven Development (TDD) FAQs

Question 1

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

Accepted Answer

The Iron Law states that no production code should be written without a failing test first. If code is written prematurely, it should be deleted to ensure the test truly verifies the behavior.

Question 2

How does this skill handle bug fixes?

Accepted Answer

It requires writing a failing test that reproduces the reported bug before any implementation code is changed, proving the fix actually works and preventing future regressions.

Question 3

Does this skill help avoid testing anti-patterns?

Accepted Answer

Yes, it specifically identifies and prevents common mistakes such as testing mock behavior instead of real code and adding test-only methods to production classes.

Question 4

Why is it mandatory to watch a test fail first?

Accepted Answer

Watching a test fail confirms that the test is actually checking the right behavior and that the failure is caused by the missing feature rather than a configuration error or typo.

Question 5

Is this skill compatible with all programming languages?

Accepted Answer

Yes, while the examples provided are in TypeScript, the TDD principles and Red-Green-Refactor workflows are language-agnostic and apply to any software development environment.

Test-Driven Development (TDD)

Key Features

Use Cases

Test-Driven Development (TDD)

Key Features

Use Cases