testing-best-practices

testing-best-practices is a skill for Claude Code, Codex from AsyrafHussin/agent-skills. It costs 58 tokens per session (1,187 once invoked), scanned A, original, MIT.

A set of guidelines for writing and reviewing unit and integration tests in TypeScript projects using Jest or Vitest. It also explains test-driven development (TDD), where tests are written before the code they check.

In plain words
What is it for?
Use it when writing or reviewing tests, planning a testing setup, or investigating flaky and slow tests. It covers test structure, isolation, assertions, test data, mocking, coverage, and performance.
Why use it?
It helps avoid tests that are unclear, dependent on one another, unreliable, or slow. It provides structure for deciding what to test and how to improve coverage.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: mentions AGENTS.md.

not rated 74repo +2 13d ago A scan Socket: passSnyk: passSkillSpector: pass 58 tokens original MIT

Good fit Use it when writing or reviewing tests, planning a testing setup, or investigating flaky and slow tests. It covers test structure, isolation, assertions, test data, mocking, coverage, and performance.

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Install with agentmods
npx agentmods add skills/asyrafhussin/agent-skills/testing-best-practices
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add AsyrafHussin/agent-skills --skill testing-best-practices
Clone the repo
git clone --depth 1 https://github.com/AsyrafHussin/agent-skills

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for testing-best-practices

README.md
[![agentmods](https://agentmods.dev/badge/skills/asyrafhussin/agent-skills/testing-best-practices/github.svg)](https://agentmods.dev/skills/asyrafhussin/agent-skills/testing-best-practices)
Your own site
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Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for testing-best-practices

Your own site · 80×15
<a href="https://agentmods.dev/skills/asyrafhussin/agent-skills/testing-best-practices"><img src="https://agentmods.dev/badge/skills/asyrafhussin/agent-skills/testing-best-practices.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 58 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,187 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • Socket pass 18 Mar 2026
  • Snyk pass 14 Mar 2026
  • NVIDIA SkillSpector pass 7 Sept 2026
How audits are shown
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00058 $0.01187
Opus 5 $0.00029 $0.00593
Sonnet 5 $0.00012 $0.00237
Haiku 4.5 $0.00006 $0.00119

Measured 10d ago against content hash db03e7c0afa7, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

testing-best-practices scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 10d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

skills/testing-best-practices/SKILL.md · 159 lines

How it starts

The opening of the file, as written. The whole thing — 159 lines — stays where its author put it; the contents beside it link to each section on GitHub.

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-

Quick Reference

1. Test Structure (CRITICAL)

  • struct-aaa-pattern - Arrange, Act, Assert pattern
  • struct-descriptive-names - Descriptive test names
  • struct-one-assertion - One logical assertion per test
  • struct-describe-it - Organized test suites with describe/it
  • struct-given-when-then - BDD style when appropriate
  • struct-setup-teardown - Proper setup and teardown

2. Test Isolation (CRITICAL)

  • iso-independent-tests - Tests run independently
  • iso-no-shared-state - No shared mutable state
  • iso-deterministic - Same result every run
  • iso-no-order-dependency - Run in any order
  • iso-cleanup - Clean up after tests
  • iso-test-doubles - Strategic use of test doubles

3. Assertions (HIGH)

  • assert-specific - Use specific assertions
  • assert-meaningful-messages - Helpful failure messages
  • assert-expected-actual - Expected value first
  • assert-no-magic-numbers - Use named constants
  • assert-custom-matchers - Custom matchers for domain logic

4. Test Data (HIGH)

  • data-factories - Use factories for test data
  • data-builders - Builder pattern for complex objects
  • data-faker - Generate realistic fake data
  • data-minimal - Minimal test data
  • data-realistic - Realistic edge cases
  • data-fixtures - Manage test fixtures

Read the full file on GitHub · 159 lines

Files

What ships with it

39 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 10d ago First seen · 159 lines · 58 tokens per session scan A db03e7c0afa7

Subscribe to this mod's changes

testing-best-practices is a skill published in the GitHub repository AsyrafHussin/agent-skills (74 stars, last pushed 13d ago), licensed MIT. It adds 58 tokens to every session and 1,187 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.