add-test

add-test is a skill for Claude Code, Codex from cyanheads/census-mcp-server. It costs 41 tokens per session (3,571 once invoked), scanned A, a copy of add-test, Apache-2.0.

A test-file scaffolding skill for an existing tool, resource, or service, using Vitest, a JavaScript and TypeScript test runner.

In plain words
What is it for?
Use it to add tests for normal behavior, errors, and edge cases, then run the project's checks.
Why use it?
It provides a starting test file when code has no matching tests or needs better coverage.

Skill for Claude CodeCodex

Part of the census-mcp-server plugin — 32 skills, 1 MCP server 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 skills/cyanheads/census-mcp-server/add-test
Any agent
npx skills add cyanheads/census-mcp-server --skill add-test
Clone the repo
git clone --depth 1 https://github.com/cyanheads/census-mcp-server

Made for: Claude Code, Codex.

Or install census-mcp-server, the plugin that ships this one along with the rest of its 32 skills, 1 MCP server.

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 add-test

README.md
[![agentmods](https://agentmods.dev/badge/skills/cyanheads/census-mcp-server/add-test.svg)](https://agentmods.dev/skills/cyanheads/census-mcp-server/add-test)
Your own site
<a href="https://agentmods.dev/skills/cyanheads/census-mcp-server/add-test"><img src="https://agentmods.dev/badge/skills/cyanheads/census-mcp-server/add-test.svg" alt="Measured on agentmods" height="20"></a>
Per session 41 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,571 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin 100% 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 $0.00041 $0.03571
Opus 5 $0.00020 $0.01785
Sonnet 5 $0.00008 $0.00714
Haiku 4.5 $0.00004 $0.00357

Measured 4d ago against content hash 9ff05d2f4834, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

add-test 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.

Origin

This is a copy

100% identical to add-test — 0 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.

skills/add-test/SKILL.md · 318 lines

How it starts

The opening of the file, as written. The whole thing — 318 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Context

Tests use Vitest and createMockContext from @cyanheads/mcp-ts-core/testing. If the repo already has tests, match the existing layout. If the repo has no existing tests, create a root tests/ directory that mirrors the src/ structure (e.g. tests/mcp-server/tools/definitions/echo.tool.test.ts for src/mcp-server/tools/definitions/echo.tool.ts).

For the full createMockContext API and testing patterns, read:

skills/api-testing/SKILL.md

Steps

  1. Identify the target — which tool, resource, or service needs tests
  2. Read the source file — understand the handler's logic, input/output schemas, error paths, and which ctx features it uses
  3. Create the test file in the repo's existing test layout — search for existing *.test.ts files to confirm whether tests are colocated with source or under a root tests/ directory
  4. Write test cases covering happy path, error paths, and edge cases
  5. Run bun run test to verify
  6. Run bun run devcheck to verify lint, types, and MCP definitions

Determining What to Test

Read the handler and identify:

Aspect Test Strategy
Happy path Valid input → expected output. Include at least one.
Input variations Optional fields omitted, defaults applied, boundary values
Error paths Invalid state, missing resources, service failures → correct error thrown
ctx.state usage Available on any mock context (tenant 'default' unless { tenantId } says otherwise). It runs the production storage path, so use storage-legal keys (cache/v1/abc, never cache:v1:abc) and assert TTL expiry with fake timers.
ctx.requestInput / ctx.inputs Two rounds. First round: assert the handler throws the input-required signal (.rejects.toSatisfy(isInputRequiredSignal)), or catch it and assert on error.result.inputRequests. Second round: seed createMockContext({ inputResponses }) and assert the handler completes. Cover the decline/cancel branch too.
ctx.signal Pass createMockContext({ signal: controller.signal }) and assert a long loop stops early rather than running to completion.
ctx.fail (typed contract) Definitions with errors[] need fail attached to the mock ctx — createMockContext({ errors: myTool.errors }) does it for you. Assert on data.reason (stable per-contract entry), not just code.
format function Test separately if defined — it's pure, no ctx needed. Verify it renders the IDs and fields the model needs, not just a count or title. For projection-style tools, test non-default field selections.
Sparse upstream payloads For third-party API integrations, build a fixture with omitted fields. Assert normalized output still validates and format() preserves unknown values instead of inventing facts.
Form-client payloads If handler has optional fields: test with empty-string inner values (form clients send "" instead of undefined). Assert handler doesn't break or produce invalid output.
Auth scopes Not tested at handler level (framework enforces) — skip

Read the full file on GitHub · 318 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. 4d ago First seen · 318 lines · 41 tokens per session scan A 9ff05d2f4834

Subscribe to this mod's changes

add-test is a skill published in the GitHub repository cyanheads/census-mcp-server (2 stars, last pushed 11d ago), licensed Apache-2.0. It adds 41 tokens to every session and 3,571 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. It is 100% identical to add-test, differing in 0 lines, and is treated as a copy.

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