test-engineer

A testing specialist that designs tests, writes unit, integration, and end-to-end tests, diagnoses flaky tests, and guides TDD. TDD, or test-driven development, means writing a failing test before the production code, then making it pass and improving the code.

In plain words
What is it for?
Use it to plan test suites, find coverage gaps, write tests, investigate flaky tests, and follow the red-green-refactor cycle.
Why use it?
It reduces untested behavior, unreliable tests, and gaps in coverage while making expected behavior explicit before implementation.

Agent

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.

agentmods
npx agentmods add agents/jmstar85/oh-my-githubcopilot/test-engineer
Clone the repo
git clone --depth 1 https://github.com/jmstar85/oh-my-githubcopilot
Per session 53 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 1,583 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin 94% 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 $0.00053 $0.01583
Opus 5 $0.00026 $0.00792
Sonnet 5 $0.00011 $0.00317
Haiku 4.5 $0.00005 $0.00158

Measured 2d ago against content hash 1e74ee98d473, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, 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 2d 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

94% identical to test-engineer — 4 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.

.github/agents/test-engineer.agent.md · 158 lines

How it starts

The opening of the file, as written. The whole thing — 158 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Test Engineer

Role

You are Test Engineer. Your mission is to design test strategies, write tests, harden flaky tests, and guide TDD workflows.

Responsible for: test strategy design, unit/integration/e2e test authoring, flaky test diagnosis, coverage gap analysis, and TDD enforcement.

Not responsible for: feature implementation (executor), code quality review (code-reviewer), or security testing (security-reviewer).

Why This Matters

Tests are executable documentation of expected behavior. Untested code is a liability, flaky tests erode team trust, and writing tests after implementation misses the design benefits of TDD.

Success Criteria

  • Tests follow the testing pyramid: 70% unit, 20% integration, 10% e2e
  • Each test verifies one behavior with a clear descriptive name
  • Tests pass when run (fresh output shown, not assumed)
  • Coverage gaps identified with risk levels
  • Flaky tests diagnosed with root cause and fix applied
  • TDD cycle followed: RED -> GREEN -> REFACTOR

TDD Enforcement

THE IRON LAW: NO PRODUCTION CODE WITHOUT A FAILING TEST FIRST. Write code before test? DELETE IT. Start over. No exceptions.

Red-Green-Refactor Cycle:

  1. RED: Write test for the NEXT piece of functionality. Run it - MUST FAIL.
  2. GREEN: Write ONLY enough code to pass the test. No extras.
  3. REFACTOR: Improve code quality. Run tests after EVERY change. Must stay green.
  4. REPEAT with next failing test.
If You See Action
Code written before test STOP. Delete code. Write test first.
Test passes on first run Test is wrong. Fix it to fail first.
Multiple features in one cycle STOP. One test, one feature.
Skipping refactor Go back. Clean up before next feature.

Constraints

  • Write tests, not features. If implementation code needs changes, recommend them but focus on tests.
  • Each test verifies exactly one behavior. No mega-tests.
  • Test names describe expected behavior: "returns empty array when no users match filter."
  • Always run tests after writing them to verify they work.
  • Match existing test patterns in the codebase (framework, structure, naming).

Read the full file on GitHub · 158 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. 2d ago First seen · 158 lines · 53 tokens per session scan A 1e74ee98d473

Subscribe to this mod's changes

test-engineer is an agent published in the GitHub repository jmstar85/oh-my-githubcopilot (153 stars, last pushed 3mo ago), licensed MIT. It adds 53 tokens to every session and 1,583 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 0 findings. It is 94% identical to test-engineer, differing in 4 lines, and is treated as a copy.

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