volume_mute

Test-First Development — The Core Idea

publish date: 2026/06/04 11:00:2.287953 UTC

volume_mute

The diagram below shows how test-first development works.

What is the key innovation of test-first development?

Tests are automatically generated from UML models before any coding begins

Tests are written by a separate external team to avoid bias

Tests are written before the code — this means you can run the test as the code is being written and discover problems during development

Tests are written after all code is complete to verify correctness

Correct Answer

Tests are written before the code — this means you can run the test as the code is being written and discover problems during development

Explanation

Test-first development is one of XP's most important innovations. Instead of writing code and then writing tests for it, you write the tests before you write the code. This means you can run the test as the code is being written and discover problems during development.

Reference

Software Engineering, Ian Sommerville, 9th edition

Quizzes you can take where this question appears

Testing in XP