npm install --save-dev @edge-runtime/jest-environment edge-runtime

{
  "jest": {
    "testEnvironment": "@edge-runtime/jest-environment"
  }
}

// pages/api/hello.ts (Vercel Edge Function)
export const config = { runtime: 'edge' };

export default async function handler(req: Request): Promise<Response> {
  return new Response(JSON.stringify({ ok: true }), {
    headers: { 'Content-Type': 'application/json' },
  });
}

import handler from './hello';

test('returns ok', async () => {
  const req = new Request('https://example.com/api/hello');
  const res = await handler(req);
  expect(res.status).toBe(200);
  expect(await res.json()).toEqual({ ok: true });
});

// middleware.ts
import { NextResponse } from 'next/server';
import type { NextRequest } from 'next/server';

export function middleware(request: NextRequest) {
  if (request.nextUrl.pathname.startsWith('/admin')) {
    if (!request.cookies.get('session')) {
      return NextResponse.redirect(new URL('/login', request.url));
    }
  }
  return NextResponse.next();
}

import { middleware } from './middleware';

test('redirects unauthenticated /admin', () => {
  const request = new Request('https://example.com/admin/dashboard');
  const response = middleware(request as any);
  expect(response.status).toBe(307);  // redirect
  expect(response.headers.get('location')).toContain('/login');
});

test('allows authenticated', () => {
  const request = new Request('https://example.com/admin', {
    headers: { cookie: 'session=valid' },
  });
  const response = middleware(request as any);
  expect(response.headers.get('x-middleware-next')).toBe('1');  // NextResponse.next sentinel
});

npm install -g vercel
vercel dev --listen 3000

npx edge-runtime ./pages/api/hello.ts
# Spins up a local server in the Edge Runtime environment

npx jest

jobs:
  vercel-edge-tests:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v5
      - uses: actions/setup-node@v4
      - run: npm ci
      - run: npx jest