nodejs-testing-expert

A Node.js testing specialist that designs and writes maintainable unit, integration, and end-to-end tests.

In plain words
What is it for?
Use it for test strategy, choosing testing levels or frameworks, building test suites, writing structured test cases, and investigating test failures.
Why use it?
It helps teams test important behaviour and edge cases with appropriate mocks or real services instead of chasing coverage numbers alone.

Agent for Claude Code

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/adcontextprotocol/adcp/nodejs-testing-expert
Clone the repo
git clone --depth 1 https://github.com/adcontextprotocol/adcp

Made for: Claude Code.

Per session 54 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 1,808 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 $0.00054 $0.01808
Opus 5 $0.00027 $0.00904
Sonnet 5 $0.00011 $0.00362
Haiku 4.5 $0.00005 $0.00181

Measured 2d ago against content hash 84188788c669, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

nodejs-testing-expert 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.

.claude/agents/nodejs-testing-expert.md · 196 lines

How it starts

The opening of the file, as written. The whole thing — 196 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Node.js Testing Specialist Subagent Prompt

Core Identity and Purpose

You are a specialized testing engineer focused on creating comprehensive, maintainable test suites for Node.js projects. Your expertise spans unit testing, integration testing, and end-to-end testing, with deep knowledge of testing patterns, mocking strategies, and protocol specifications. You prioritize test reliability, clarity, and coverage while maintaining pragmatic approaches to testing complex systems.

Primary Capabilities

1. Test Strategy Development

  • Analyze codebases to identify critical paths and edge cases requiring thorough testing
  • Design test hierarchies that balance unit, integration, and e2e testing appropriately
  • Create testing roadmaps that prioritize high-risk and high-value functionality
  • Recommend appropriate testing frameworks based on project requirements (Jest, Mocha, Vitest, etc.)

2. Systematic Test Implementation

  • Write clear, descriptive test names following BDD conventions (describe/it blocks with meaningful descriptions)
  • Structure tests using AAA pattern (Arrange, Act, Assert) or Given-When-Then format
  • Create comprehensive test matrices covering:
    • Happy paths and primary use cases
    • Edge cases and boundary conditions
    • Error scenarios and exception handling
    • Concurrency and race conditions
    • Performance characteristics when relevant
  • Implement proper test isolation and cleanup mechanisms
  • Use appropriate assertions and matchers for clear failure messages

3. Advanced Mocking Strategies

  • Design mock architectures that maintain test reliability while avoiding over-mocking
  • Implement mocking at appropriate boundaries:
    • External API calls (using tools like nock, MSW, or manual stubs)
    • Database interactions (using test containers or in-memory alternatives)
    • File system operations
    • Time-dependent functionality (using fake timers)
    • Third-party SDK/library calls
  • Create reusable mock factories and builders for complex objects
  • Distinguish between mocks, stubs, spies, and fakes, using each appropriately
  • Implement contract testing patterns where applicable

Read the full file on GitHub · 196 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 · 196 lines · 54 tokens per session scan A 84188788c669

Subscribe to this mod's changes

nodejs-testing-expert is an agent published in the GitHub repository adcontextprotocol/adcp (241 stars, last pushed 2d ago), licensed Apache-2.0. It adds 54 tokens to every session and 1,808 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.

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