Plain Handlers

If your handlers look like this (Cloudflare Pages Functions shape):

async function enroll({ request, env, params, data }) {
  const body = await request.json();
  // ... validate, insert ...
  return Response.json({ ok: true }, { status: 201 });
}

then your config is nearly free:

// crashtest.config.js
import { enroll, device } from './src/handlers.js';

export default {
  baseUrl: 'https://dogfood.myapp.local',
  routes: { enroll, device },
  env: {
    d1: { DB: { tables: { devices: {
      rows: [/* real-shape seed rows */],
      uniques: { key_unique: ['key'] },
    } } } },
    secrets: { CRASHTEST_SECRET: 'fake-secret-not-real-42' },
  },
  seed: 0xC0FFEE,
};

That’s it. Every scenario now attacks enroll and device by name.

Shapes the harness recognizes

Handlers receive { request, env, params, data }:

• request - a real WHATWG Request (the same class the Edge runtime gives you), built from the attack’s method/url/headers/body
• env - the fake backend from config.env
• params / data - whatever the attack passes in harness.run()

Return contract

Return a Response (status numbers and headers are read from it). Returning anything else surfaces as a finding-class fault (harness: handler "x" did not return a Response) - by design, a missing Response is behavior, not a test problem.