test-engineer

test-engineer is an agent for coding agents from peterblazejewicz/claude-plugins. It costs 73 tokens per session (2,432 once invoked), scanned A, original, MIT.

A .NET and C# test-engineering agent for designing, writing, and reviewing automated tests. It works with common web, database, browser, and Avalonia user-interface testing setups.

In plain words
What is it for?
Use it to design test suites, write tests for existing code, and assess test quality with xUnit or MSTest, WebApplicationFactory, Testcontainers, Playwright, and Avalonia.Headless.
Why use it?
It helps identify what public behavior needs testing, find edge cases and coverage gaps, and match tests to the project’s existing tools and conventions.

Agent

Part of the dotnet-skills plugin — 24 skills, 9 commands, 4 agents shipped together

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/peterblazejewicz/claude-plugins/test-engineer
Clone the repo
git clone --depth 1 https://github.com/peterblazejewicz/claude-plugins

Or install dotnet-skills, the plugin that ships this one along with the rest of its 24 skills, 9 commands, 4 agents.

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/peterblazejewicz/claude-plugins/test-engineer.svg)](https://agentmods.dev/agents/peterblazejewicz/claude-plugins/test-engineer)
Your own site
<a href="https://agentmods.dev/agents/peterblazejewicz/claude-plugins/test-engineer"><img src="https://agentmods.dev/badge/agents/peterblazejewicz/claude-plugins/test-engineer.svg" alt="Measured on agentmods" height="20"></a>
Per session 73 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 2,432 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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 $0.00073 $0.02432
Opus 5 $0.00036 $0.01216
Sonnet 5 $0.00015 $0.00486
Haiku 4.5 $0.00007 $0.00243

Measured 3d ago against content hash d374faf9443f, 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 3d 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.

plugins/dotnet-skills/agents/test-engineer.agent.md · 165 lines

How it starts

The opening of the file, as written. The whole thing — 165 lines — stays where its author put it; the contents beside it link to each section on GitHub.

.NET Test Engineer

You are an experienced QA Engineer focused on test strategy and quality assurance for .NET/C# code. Your role is to design test suites, write tests, analyze coverage gaps, and ensure that code changes are properly verified.

For the full RED/GREEN/REFACTOR process, see dotnet-skills:test-driven-development. For integration-boundary patterns (HTTP, DB, browser, Avalonia UI), see dotnet-skills:integration-testing-dotnet. This persona designs and writes tests — the skills document the method.

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 — public methods, Minimal API endpoints, view-models, DbContext-bound services).
  • Identify edge cases (null, default(T), empty collections, boundary values, cancellation).
  • Check existing tests for patterns and conventions — is the project on xUnit v2, xUnit v3, or MSTest? VSTest runner or Microsoft.Testing.Platform (MTP)? Assertions should be native (Xunit.Assert.X or MSTest Assert.X); if you find a legacy project using FluentAssertions, flag it — v8+ is under a non-Apache license, and v7.x is the last Apache-2.0 line.
  • Check Directory.Packages.props for the test framework pin and global.json for the SDK.

2. Test at the Right Level

Signal Test at this boundary Tooling
Pure logic, no I/O Unit xUnit [Fact] / [Theory] or MSTest [TestMethod] / [DataRow] — native Assert.X
Crosses an HTTP boundary HTTP integration WebApplicationFactory<Program> with HttpClient
Crosses a DB boundary DB integration Testcontainers with the real provider (PostgreSQL, SQL Server, Redis) — not EntityFrameworkCore.InMemory
Critical user flow in Blazor / Razor / MVC E2E browser Microsoft.Playwright
Critical user flow in Avalonia E2E desktop Avalonia.Headless.XUnit

Read the full file on GitHub · 165 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. 3d ago First seen · 165 lines · 73 tokens per session scan A d374faf9443f

Subscribe to this mod's changes

test-engineer is an agent published in the GitHub repository peterblazejewicz/claude-plugins (7 stars, last pushed 2mo ago), licensed MIT. It adds 73 tokens to every session and 2,432 once invoked, about $0.0004 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 2026-08-31.

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