test-engineer

test-engineer is an agent for Claude Code from az9713/addyosmani-agent-skills. It costs 35 tokens per session (621 once invoked), scanned A, a copy of test-engineer, MIT.

A QA-focused coding agent for planning tests, writing them, and finding gaps in test coverage.

In plain words
What is it for?
Use it to design unit, integration, or end-to-end tests, test bug fixes, review existing test quality, and assess missing coverage.
Why use it?
It helps verify behavior at the appropriate level and exposes untested edge cases and error paths before problems reach users.

Agent for Claude Code

Written for Claude Code: shipped in a Claude Code plugin.

Part of the agent-skills plugin — 20 skills, 7 commands, 3 agents, 1 hook shipped together

Good fit Use it to design unit, integration, or end-to-end tests, test bug fixes, review existing test quality, and assess missing coverage.

Compare 6 agents from other repositories ↓
Install with agentmods
npx agentmods add agents/az9713/addyosmani-agent-skills/test-engineer
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.

Clone the repo
git clone --depth 1 https://github.com/az9713/addyosmani-agent-skills

Made for: Claude Code.

Or install agent-skills, the plugin that ships this one along with the rest of its 20 skills, 7 commands, 3 agents, 1 hook.

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 test-engineer

README.md
[![agentmods](https://agentmods.dev/badge/agents/az9713/addyosmani-agent-skills/test-engineer.svg)](https://agentmods.dev/agents/az9713/addyosmani-agent-skills/test-engineer)
Your own site
<a href="https://agentmods.dev/agents/az9713/addyosmani-agent-skills/test-engineer"><img src="https://agentmods.dev/badge/agents/az9713/addyosmani-agent-skills/test-engineer.svg" alt="Measured on agentmods" height="20"></a>
Per session 35 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 621 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.
Origin 84% copy Near-identical to another mod 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 $0.00035 $0.00621
Opus 5 $0.00017 $0.00311
Sonnet 5 $0.00007 $0.00124
Haiku 4.5 $0.00003 $0.00062

Measured 8d ago against content hash 7fa49278ec97, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

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 8d 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.

Origin

This is a copy

84% identical to test-engineer — 6 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

agents/test-engineer.md · 90 lines

How it starts

The opening of the file, as written. The whole thing — 90 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:

  1. Write a test that demonstrates the bug (must FAIL with current code)
  2. Confirm the test fails
  3. 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]

Read the full file on GitHub · 90 lines

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. 8d ago First seen · 90 lines · 35 tokens per session scan A 7fa49278ec97

Subscribe to this mod's changes

test-engineer is an agent published in the GitHub repository az9713/addyosmani-agent-skills (36 stars, last pushed 5mo ago), licensed MIT. It adds 35 tokens to every session and 621 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. It is 84% identical to test-engineer, differing in 6 lines, and is treated as a copy.

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