Test design

Overview

Design the smallest test set that can falsify the important behavior. Keep routine implementation proof in engineering. Use this skill when the test shape is the deliverable or the main uncertainty.

When to Use

• Explicit TDD or test-first feature work
• Selecting unit, integration, contract, property, state-machine, or end-to-end proof
• Designing assertions, fixtures, or real/fake/mock boundaries
• Adding focused tests for known behavior or legacy characterization

When Not to Use

• Use debugging first when the failure or failing boundary is unknown
• Use engineering when test choice is routine support for an understood change
• Use improve-test-suite for a repo- or subsystem-wide test-suite audit