next.js/test/e2e/app-dir/service-worker-multiple/service-worker-multiple.test.ts

import { nextTestSetup } from 'e2e-utils'
import { retry } from 'next-test-utils'

// Compiling `navigator.serviceWorker.register(new URL(...))` is a Turbopack-only feature.
;(process.env.IS_TURBOPACK_TEST ? describe : describe.skip)(
  'app dir - service worker (multiple registrations error)',
  () => {
    const { next, skipped, isNextDev } = nextTestSetup({
      files: __dirname,
      skipStart: true,
      // This test asserts a build failure.
      skipDeployment: true,
    })

    if (skipped) {
      return
    }

    it('errors when different service worker files are registered', async () => {
      // In production `next.start()` runs the build, which fails. In dev the server
      // boots and the failure surfaces when the registering page is compiled.
      await next.start().catch(() => {})
      if (isNextDev) {
        await next.fetch('/').catch(() => {})
      }

      await retry(async () => {
        expect(next.cliOutput).toContain(
          'Multiple service workers with different source files'
        )
      })
    })
  }
)