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 skills/bartstc/vite-ts-react-template/test-building-blocksnpx skills add bartstc/vite-ts-react-template --skill test-building-blocksgit clone --depth 1 https://github.com/bartstc/vite-ts-react-templateWrote 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/skills/bartstc/vite-ts-react-template/test-building-blocks)<a href="https://agentmods.dev/skills/bartstc/vite-ts-react-template/test-building-blocks"><img src="https://agentmods.dev/badge/skills/bartstc/vite-ts-react-template/test-building-blocks.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 | $0.00088 | $0.01235 |
| Opus 5 | $0.00044 | $0.00617 |
| Sonnet 5 | $0.00018 | $0.00247 |
| Haiku 4.5 | $0.00009 | $0.00123 |
Grade A, and why
test-building-blocks 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.
How it starts
The opening of the file, as written. The whole thing — 82 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Test Building Blocks
Typed catalog of test-related building blocks used in this project. Each block has a fixed name, layer, composition rules, and canonical example.
How to Use
Read the rule file for each block you are about to implement. The summaries below are for routing — the rule files contain the full pattern.
Typical flow:
- Read this file to route to the right block.
- Read
rules/{block-name}.mdfor the full pattern and canonical example. - Read the implementation code (component, hook, module) you are testing.
- Write the test following the rule file's constraints.
Testing Philosophy
The project's testing philosophy allocates verification across three layers:
- Storybook play-function tests are the primary verification layer for feature behavior. Focus on happy paths and the main user-observable states. Anything user-facing — components composing hooks, stores, providers — is verified here.
- Vitest hook tests (
renderHook) cover custom hooks that need dedicated verification — edge cases, error paths, loading states, and hooks with logic not tied to a single component. Use independently ofcomponent-story-test; the two do not need to cover the same ground. - Vitest unit tests are reserved for non-hook mechanics: mappers, transformers, value objects, selectors, and other pure logic.
- No tests for fixtures, MSW handlers, or trivial glue — these are support infrastructure, not the thing being verified.
Coverage is behavior-covered, not file-mapped. Every user-observable state has a story or a hook-test scenario; not every file has a test.
Mocking Boundary
Mock at the network boundary, not the module boundary. MSW is the default for anything HTTP-backed. Do not mock lib/api/ exports, React Query, or Zustand stores — let the real code run and intercept at the wire.
Module-level mocking (vi.mock, vi.stubGlobal) is reserved for:
- Non-determinism sources:
Date.now,crypto.randomUUID,Math.random, timers. - Write-only side-effect sinks: analytics, logging, toasts — centralized as project-owned spies in
test-lib/. - Pure utilities when unit-testing their direct caller.
- XState actors/actions via
machine.provide({ actors, actions }).
What ships with it
7 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
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 · 82 lines · 0 tokens per session scan A c86d48cbda83
test-building-blocks is a skill published in the GitHub repository bartstc/vite-ts-react-template (121 stars, last pushed 1mo ago), licensed MIT. It adds 88 tokens to every session and 1,235 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 2026-08-30.
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