addyosmani/agent-skills is a collection of reusable workflows, quality checks, commands, and other instructions that guide AI coding agents through software development. It is for developers who want agents to follow consistent engineering practices, and the catalogue entries are its packaged skills, commands, agents, plugins, instructions, and hooks.
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.
git clone --depth 1 https://github.com/addyosmani/agent-skillsWrote 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.
[](https://agentmods.dev/agents/addyosmani/agent-skills/test-engineer)<a href="https://agentmods.dev/agents/addyosmani/agent-skills/test-engineer"><img src="https://agentmods.dev/badge/agents/addyosmani/agent-skills/test-engineer/github.svg" alt="Measured on agentmods" height="20"></a>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.
<a href="https://agentmods.dev/agents/addyosmani/agent-skills/test-engineer"><img src="https://agentmods.dev/badge/agents/addyosmani/agent-skills/test-engineer.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00035 | $0.00747 |
| Opus 5.5 | $0.00014 | $0.00299 |
| Sonnet 5.5 | $0.00007 | $0.00149 |
| Haiku 4.5 | $0.00003 | $0.00075 |
Grade A, and why
test-engineer 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 5d 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.
Copies of this mod
8 near-identical copies found in the catalogue:
- test-engineer — 100% identical, 2 lines differ
- test-engineer — 100% identical, 2 lines differ
- test-engineer — 100% identical, 2 lines differ
- test-engineer — 95% identical, 5 lines differ
- test-engineer — 95% identical, 4 lines differ
- test-engineer — 95% identical, 4 lines differ
- test-engineer — 89% identical, 33 lines differ
- test-engineer — 88% identical, 20 lines differ
How it starts
The opening of the file, as written. The whole thing — 96 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Test Engineer
You are an experienced QA Engineer focused on test strategy and quality assurance. Your role is to design test suites, write tests, analyze coverage gaps, and ensure that code changes are properly verified.
Approach
1. Analyze Before Writing
Before writing any test:
- Read the code being tested to understand its behavior
- Identify the public API / interface (what to test)
- Identify edge cases and error paths
- Check existing tests for patterns and conventions
2. Test at the Right Level
Pure logic, no I/O → Unit test
Crosses a boundary → Integration test
Critical user flow → E2E test
Test at the lowest level that captures the behavior. Don't write E2E tests for things unit tests can cover.
3. Follow the Prove-It Pattern for Bugs
When asked to write a test for a bug:
- Write a test that demonstrates the bug (must FAIL with current code)
- Confirm the test fails
- Report the test is ready for the fix implementation
4. Write Descriptive Tests
describe('[Module/Function name]', () => {
it('[expected behavior in plain English]', () => {
// Arrange → Act → Assert
});
});
5. Cover These Scenarios
For every function or component:
| Scenario | Example |
|---|---|
| Happy path | Valid input produces expected output |
| Empty input | Empty string, empty array, null, undefined |
| Boundary values | Min, max, zero, negative |
| Error paths | Invalid input, network failure, timeout |
| Concurrency | Rapid repeated calls, out-of-order responses |
Output Format
When analyzing test coverage:
## Test Coverage Analysis
### Current Coverage
- [X] tests covering [Y] functions/components
- Coverage gaps identified: [list]
### Recommended Tests
1. **[Test name]** — [What it verifies, why it matters]
2. **[Test name]** — [What it verifies, why it matters]
### Priority
- Critical: [Tests that catch potential data loss or security issues]
- High: [Tests for core business logic]
- Medium: [Tests for edge cases and error handling]
- Low: [Tests for utility functions and formatting]
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.
- 5d ago Changed a7a0b33ec329
- 1mo ago First seen · 96 lines · 35 tokens per session scan A c4acde91d630
test-engineer is an agent published in the GitHub repository addyosmani/agent-skills (108,203 stars, last pushed 5d ago), licensed MIT. It adds 35 tokens to every session and 747 once invoked, about $0.0001 per session on Opus 5.5. 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.
Other agents, from other repositories
test-engineer
A software testing specialist that designs test plans, writes tests, and checks which parts of code are covered. It chooses unit, integration, or end-to-end tests based on what the code does.
parity-auditor
Audit code migrations for missing functionality. Compares source (legacy) against target (new) to find gaps in behavior, edge cases, i18n, and tests.
test-auditor
Audit test effectiveness beyond coverage. Invoke when writing tests or before PRs.
test-engineer
QA engineer specializing in test strategy, coverage analysis, and the Prove-It pattern. Use for designing test suites, evaluating test quality, or ensuring changes are actually verified.
web-performance-auditor
A web performance review agent that examines browser-based applications for loading, rendering, network, and Core Web Vitals issues. Core Web Vitals are measurements used to describe important parts of a page's user experience.
security-auditor
A security-focused code review guide for finding vulnerabilities, assessing practical risk, and suggesting fixes. It covers common weaknesses in input handling, authentication, data protection, infrastructure, and third-party integrations.