Testing Best Practices

A comprehensive testing reference that covers the fundamentals through 34 rules organized by priority, from critical test structure and isolation patterns down to performance optimizations. You'll want this when writing new tests, reviewing PRs, or setting up testing infrastructure. It's opinionated about the AAA pattern, test independence, and strategic mocking at boundaries rather than everywhere. The examples use TypeScript with Jest/Vitest, and it's honest about controversial topics like why 100% coverage shouldn't be your goal. The rule prefixes make it easy to scan for what matters most when you're in a hurry.

skills.sh installs: 957
GitHub stars: 102
last updated: Aug 21, 2026

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Install

$ npx -y skills add asyrafhussin/agent-skills --skill testing-best-practices --agent claude-code

Installs into .claude/skills of the current project.

Files

Testing Best Practices

Unit testing, integration testing, and TDD principles for reliable, maintainable test suites. Contains 34 rules across 7 categories using TypeScript with Jest/Vitest.

Metadata

Version: 2.0.0
Rule Count: 34 rules across 7 categories
License: MIT

When to Apply

Reference these guidelines when:

Writing unit or integration tests
Reviewing test code quality
Improving test coverage strategy
Setting up testing infrastructure
Debugging flaky or slow tests

Rule Categories by Priority

Priority	Category	Impact	Prefix
1	Test Structure	CRITICAL	`struct-`
2	Test Isolation	CRITICAL	`iso-`
3	Assertions	HIGH	`assert-`
4	Test Data	HIGH	`data-`
5	Mocking	MEDIUM	`mock-`
6	Coverage	MEDIUM	`cov-`
7	Performance	LOW	`perf-`