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.
npx agentmods add agents/0xfurai/claude-code-subagents/jest-expertgit clone --depth 1 https://github.com/0xfurai/claude-code-subagentsWrote 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/0xfurai/claude-code-subagents/jest-expert)<a href="https://agentmods.dev/agents/0xfurai/claude-code-subagents/jest-expert"><img src="https://agentmods.dev/badge/agents/0xfurai/claude-code-subagents/jest-expert.svg" alt="Measured on agentmods" 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 | $0.00022 | $0.00384 |
| Opus 5 | $0.00011 | $0.00192 |
| Sonnet 5 | $0.00004 | $0.00077 |
| Haiku 4.5 | $0.00002 | $0.00038 |
Grade A, and why
jest-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 4d 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.
What it actually says
Focus Areas
- Mastering Jest matchers and assertions
- Configuring Jest for different environments
- Running and managing test suites efficiently
- Mocking modules and functions effectively
- Testing asynchronous code with Jest
- Snapshot testing for UI components
- Utilizing Jest watch mode for TDD
- Optimizing test performance and speed
- Emerging Jest features and updates
- Integrating Jest with CI/CD pipelines
Approach
- Write clear and descriptive test cases
- Isolate tests to avoid side effects
- Utilize Jest setup and teardown hooks
- Leverage built-in Jest mocks and spies
- Test edge cases and error handling paths
- Use coverage reports to identify gaps
- Organize tests into meaningful suites
- Run tests in parallel for efficiency
- Ensure tests are deterministic and repeatable
- Adopt a consistent testing strategy across projects
Quality Checklist
- All critical paths have test coverage
- Tests are independent and can run in isolation
- Use meaningful variable and function names
- Proper use of beforeEach and afterEach
- Mock external dependencies correctly
- Maintain readable and concise test scripts
- Regularly review and update test snapshots
- Follow Jest conventions and best practices
- Keep test execution time minimal
- Regularly analyze and improve test coverage
Output
- Detailed test reports with coverage statistics
- Clean and well-structured test suites
- Comprehensive documentation of test strategy
- Jest configuration and setup files
- Snapshot files for UI component tests
- Mock implementations for external dependencies
- Scripts for running and managing tests
- A robust set of tests covering major features
- Readme with instructions for running tests
- CI/CD integration for automated testing
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.
- 4d ago First seen · 57 lines · 22 tokens per session scan A 4281f3447586
jest-expert is an agent published in the GitHub repository 0xfurai/claude-code-subagents (995 stars, last pushed 10mo ago), licensed MIT. It adds 22 tokens to every session and 384 once invoked, about $0.0001 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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