v0.4.6 Available

Test Reality.
Control the Rest.

Playwright tests that hit your real server. Your Server Components, routes, middleware, and business logic execute for real. Scenarist mocks only external APIs—switchable per test.

Get Started

Built for full-stack frameworks

Next.js Express Playwright
scenario.ts | checkout.spec.ts
Define Scenario 
const successScenario = {
  id: 'payment_success',
  mocks: [{
    url: 'https://api.stripe.com/*',
    method: 'POST',
    response: {
      status: 200,
      body: { paid: true }
    }
  }]
};
Run Test 
test('checkout flow', async ({ page }) => {
  await switchScenario(page, 'payment_success');

  // Hits real Next.js backend
  await page.goto('/checkout');
  await page.click('#pay-button');

  // Real DB, Real Middleware, Mocked Stripe
  await expect(page).toHaveURL('/success');
});

Why Scenarist?

The Testing Gap

Fast like unit tests, realistic like integration tests

Parallel Execution

Isolated test state means unlimited parallelism

Behavior Testing

Test scenarios, not implementation details

Only mock what you don't control

Scenarist acts as a precision scalpel. It slices off external dependencies while leaving your application logic perfectly intact.

Your Application
Running Real Code

Executes For Real

Server Components
API Routes
Middleware
Zod Validation
Session Cookies
The Edge

Mocked by Scenarist

Stripe API JSON
Auth0 JWT
SendGrid 202

Next.js Adapters

Full support for both App Router and Pages Router. Test React Server Components, Server Actions, and API Routes with real execution—your async components fetch data for real, only external APIs are mocked.

Server Components Server Actions App Router Pages Router
View docs

Express Adapter

Full Express support. Routes, middleware, error handlers—all run for real. More adapters planned.

View docs

Instant Runtime Switching

Switch scenarios instantly without restarting your server. Tests run in parallel with isolated state—fast like unit tests, realistic like integration tests.

Type-Safe

Built for Playwright. TypeScript autocomplete for your scenario IDs. Never debug a typo again.

No Framework Mocking

No mocking next/headers. No mocking req.session. Your app code runs as-is.

Playwright Helpers

Each test gets a unique ID. Call switchScenario(page, 'premium-user') and all requests from that test use your scenario. Run tests in parallel—each isolated, each with different API responses.

View docs