What is svelte-testing?

A testing guide and toolkit for Svelte 5 interfaces, using Vitest and Playwright to check browser behavior, server rendering, and APIs. Svelte is a framework for building web interfaces.

Use it to write or fix Svelte component tests, server-side rendering tests, API tests, and browser end-to-end tests.

It helps diagnose broken tests and avoid fragile tests that pass for the wrong reasons or fail because they interact with components incorrectly.

svelte-testing — Skill for Claude Code and Codex by spences10: A testing guide and toolkit for Svelte 5 interfaces…

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/spences10/sveltest/svelte-testing

Any agent

npx skills add spences10/sveltest --skill svelte-testing

Clone the repo

git clone --depth 1 https://github.com/spences10/sveltest

Made for: Claude Code, Codex.

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.

README.md

[![agentmods](https://agentmods.dev/badge/skills/spences10/sveltest/svelte-testing.svg)](https://agentmods.dev/skills/spences10/sveltest/svelte-testing)

Your own site

<a href="https://agentmods.dev/skills/spences10/sveltest/svelte-testing"><img src="https://agentmods.dev/badge/skills/spences10/sveltest/svelte-testing.svg" alt="Measured on agentmods" height="20"></a>

Per session 49 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 490 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.

Model	Per session	Once invoked
Fable 5	$0.00049	$0.00490
Opus 5	$0.00024	$0.00245
Sonnet 5	$0.00010	$0.00098
Haiku 4.5	$0.00005	$0.00049

Measured 5d ago against content hash f5f871419c07, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

svelte-testing 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 5d 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.

.agents/skills/svelte-testing/SKILL.md · 59 lines

What it actually says

Svelte Testing

Quick Start

// Client-side component test (.svelte.test.ts)
import { render } from 'vitest-browser-svelte';
import { expect } from 'vitest';
import Button from './button.svelte';

test('button click increments counter', async () => {
	const { page } = render(Button);
	const button = page.getByRole('button', { name: /click me/i });

	await button.click();
	await expect.element(button).toHaveTextContent('Clicked: 1');
});

Core Principles

Always use locators: page.getBy*() methods, never containers
Multiple elements: Use .first(), .nth(), .last() to avoid strict mode violations
Use untrack(): When accessing $derived values in tests
Real API objects: Test with FormData/Request, minimal mocking

Reference Files

Notes

Never click SvelteKit form submit buttons - Always use await expect.element()
Test files: .svelte.test.ts (client), .ssr.test.ts (SSR), server.test.ts (API)

Files

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.

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.

5d ago First seen · 59 lines · 49 tokens per session scan A f5f871419c07

Subscribe to this mod's changes

svelte-testing is a skill published in the GitHub repository spences10/sveltest (113 stars, last pushed yesterday), licensed MIT. It adds 49 tokens to every session and 490 once invoked, about $0.0002 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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svelte-testing