Testing Software

Overview

Use this skill to choose reliable tests with the least cost. Tests should verify behavior through public interfaces and externally visible contracts. When a bug fix or behavior change has a cheap trustworthy failing test, bias toward TDD. Producer standard: tests shaped by this skill should not create new improve-test-suite findings for brittleness, mock theater, redundancy, or low signal unless the tradeoff is explicit.

When to Use

• Choosing unit, integration, end-to-end, or exploratory coverage
• Deciding what must stay real, what can be faked, and what should be mocked
• Writing acceptance criteria or concrete assertions
• Evaluating a bounded test slice for brittleness, cost, or weak signal
• Using TDD deliberately for a slice of behavior
• Fixing an understood regression when a cheap trustworthy failing test already exists
• Designing characterization, contract, property, state-machine, or golden tests for risky behavior

When Not to Use