memstack-development-webapp-testing

A guide for writing Playwright end-to-end tests, which control a real web browser to check complete user journeys. It helps identify the application, framework, authentication needs, and key flows to test.

In plain words
What is it for?
Use it to test pages, sign-up and login flows, searches, checkouts, and other browser-based interactions in a web application.
Why use it?
It helps verify that the interface works from a user's point of view, rather than checking only isolated functions or API responses.

Skill for Claude CodeCodex

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/cwinvestments/memstack/webapp-testing
Any agent
npx skills add cwinvestments/memstack --skill webapp-testing
Clone the repo
git clone --depth 1 https://github.com/cwinvestments/memstack

Made for: Claude Code, Codex.

Per session 75 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,598 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. 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.

ModelPer sessionOnce invoked
Fable 5 $0.00075 $0.01598
Opus 5 $0.00037 $0.00799
Sonnet 5 $0.00015 $0.00320
Haiku 4.5 $0.00007 $0.00160

Measured 2d ago against content hash 7c5fd3ad4d11, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

memstack-development-webapp-testing scanned grade A with 1 finding 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 2d 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.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

- Do NOT use for API-only testing (use curl/fetch patterns)
skills/development/webapp-testing/SKILL.md · 217 lines

How it starts

The opening of the file, as written. The whole thing — 217 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Webapp Testing — Writing browser tests...

Produces Playwright end-to-end tests that verify real user flows in a browser.

Activation

Trigger Status
User says "write browser tests" or "playwright test" ACTIVE
User says "test this page" or "e2e test" ACTIVE
User says "test the UI" or "browser test" ACTIVE
User wants unit tests or API tests NOT this skill — use standard test patterns
User wants load testing NOT this skill

Context Guard

  • Do NOT use for unit tests (Jest, Vitest without browser)
  • Do NOT use for API-only testing (use curl/fetch patterns)
  • Do NOT use for performance benchmarking
  • This skill ONLY produces Playwright browser tests

Steps

Step 1: Assess the target

Determine what to test:

Parameter How to find Example
App URL Check package.json scripts, .env, or ask http://localhost:3000
Framework Check package.json dependencies Next.js, React, SvelteKit
Auth required? Check for login pages, auth middleware Yes/No
Key user flows Ask or infer from routes Sign up, checkout, search
# Check if Playwright is already installed
cat package.json | grep -i playwright

# Check existing test structure
find . -name "*.spec.ts" -o -name "*.test.ts" | head -20

Step 2: Set up Playwright (if not installed)

npm init playwright@latest
# or
pnpm add -D @playwright/test
npx playwright install

Confirm playwright.config.ts exists. If not, create with sensible defaults:

import { defineConfig, devices } from '@playwright/test';

export default defineConfig({
  testDir: './tests/e2e',
  fullyParallel: true,
  forbidOnly: !!process.env.CI,
  retries: process.env.CI ? 2 : 0,
  workers: process.env.CI ? 1 : undefined,
  reporter: 'html',
  use: {
    baseURL: 'http://localhost:3000',
    trace: 'on-first-retry',
    screenshot: 'only-on-failure',
  },
  projects: [
    { name: 'chromium', use: { ...devices['Desktop Chrome'] } },
  ],
  webServer: {
    command: 'npm run dev',
    url: 'http://localhost:3000',
    reuseExistingServer: !process.env.CI,
  },
});

Read the full file on GitHub · 217 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. 2d ago First seen · 217 lines · 75 tokens per session scan A 7c5fd3ad4d11

Subscribe to this mod's changes

memstack-development-webapp-testing is a skill published in the GitHub repository cwinvestments/memstack (417 stars, last pushed 5d ago), licensed MIT. It adds 75 tokens to every session and 1,598 once invoked, about $0.0004 per session on Opus 5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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