Playwright fixtures + InboxTap

Start InboxTap as a worker fixture, then start an application-like worker fixture that consumes its dynamic SMTP settings. Each Playwright test receives a fresh inbox without reserving fixed ports or starting a browser.

Prerequisites

• Node.js 20 or later

Setup

npm install

No browser download is needed because this example exercises fixture composition without the page fixture.

Run the tests

npm test

Playwright starts and tears down the complete fixture dependency chain for each worker.

How it works

import { test as base } from "@playwright/test";
import { extendInboxTap } from "inboxtap/fixtures/playwright";
import nodemailer from "nodemailer";

interface App {
  sendWelcome(to: string): Promise<void>;
}

const withInboxTap = extendInboxTap(base);

export const test = withInboxTap.extend<object, { app: App }>({
  app: [
    async ({ inboxTap }, use) => {
      const transport = nodemailer.createTransport(inboxTap.smtp);
      await transport.verify();
      try {
        await use({
          async sendWelcome(to) {
            await transport.sendMail({
              from: "app@local.test",
              to,
              subject: "Welcome",
              text: "Your account is ready.",
            });
          },
        });
      } finally {
        transport.close();
      }
    },
    { scope: "worker" },
  ],
});

The app worker fixture depends on the inboxTap worker fixture, so Playwright starts InboxTap first and closes it last. The runnable example uses a small mail-sending object in place of a web application to keep the lifecycle easy to see.

Isolation and cleanup

InboxTap is shared only at worker scope; the adapter injects a new inbox for every test. The application fixture owns its transport, and dependency-ordered teardown closes that transport before InboxTap stops.

Do not use Playwright's webServer option when the application needs InboxTap's dynamic SMTP port: webServer starts before test fixtures exist. Start the application as a dependent worker fixture, as this example does.

Troubleshooting

• The application cannot connect — create its transport from inboxTap.smtp; do not copy a fixed port into the configuration.
• The app starts before InboxTap — list inboxTap in the app fixture's dependency arguments.
• A browser executable is missing — this example does not use page; remove browser fixtures from copied tests or install the browser your application tests require.