Borrowing it
Nothing to install: this file belongs to evmts/tevm. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/evmts/tevm/main/.claude/commands/add-test-matcher.mdgit clone --depth 1 https://github.com/evmts/tevmWrote 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/commands/evmts/tevm/add-test-matcher)<a href="https://agentmods.dev/commands/evmts/tevm/add-test-matcher"><img src="https://agentmods.dev/badge/commands/evmts/tevm/add-test-matcher/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/commands/evmts/tevm/add-test-matcher"><img src="https://agentmods.dev/badge/commands/evmts/tevm/add-test-matcher.svg" alt="Reviewed on agentmods" width="80" 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 5.1 | $0.00000 | $0.02879 |
| Opus 5.5 | $0.00000 | $0.01152 |
| Sonnet 5.5 | $0.00000 | $0.00576 |
| Haiku 4.5 | $0.00000 | $0.00288 |
Grade A, and why
add-test-matcher 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 1mo 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.
How it starts
The opening of the file, as written. The whole thing — 355 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Add Test Matcher
This command helps you create new Vitest matchers for the @tevm/test-matchers package. The workflow combines user requirement gathering with comprehensive implementation guidance.
Step 1: Gather Requirements
Before implementing a new test matcher, I need to understand what you want to create. Please provide the following information:
A. Matcher Details
- Primary Matcher Name: What should the main matcher be called? (e.g.,
toBeValidUser,toHaveLength) - Category: What category does this matcher belong to? (e.g.,
user,collection,database) - Chained Matchers: If this is a chainable matcher, what secondary matchers should be available? (e.g.,
withRole,withProperty)
B. Behavior Description
- Synchronicity: Is this matcher synchronous or asynchronous?
- Chainability: Is this a simple matcher or a chainable matcher?
- Functionality: What should the matcher do? Be specific about arguments, expected behavior, and what constitutes pass/fail conditions.
C. Example Usage
Provide examples of how you envision using the matcher:
// Example:
expect(userId).toBeValidUser()
expect(userId).toBeValidUser().withRole('admin')
Step 2: Implementation Guide
Once you provide the requirements above, I'll implement the matcher following the architectural patterns below.
Core Architecture
The matcher system is built on a modular, category-based structure that plugs into vitest's expect API.
Key Directories & Files
src/index.ts: The central entry point for registering matchers withvitestsrc/common/: Contains shared TypeScript types across matcher categoriessrc/chainable/: Core engine for chainable assertions (DO NOT modify)src/matchers/: Root directory for all matcher implementationssrc/matchers/<category>/: Each subdirectory represents a logical grouping of related matcherssrc/matchers/<category>/index.ts: Entry point for a category, exports all public matchers and interfaces
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.
- 1mo ago First seen · 355 lines · 0 tokens per session scan A a5488a32e2a9
add-test-matcher is a command published in the GitHub repository evmts/tevm (449 stars, last pushed 1mo ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 2,879 tokens. 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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