[Regression]: Tests fails in parallel run when click on dropdown options performed

[mikhail-shafigullin]

Last Good Version

1.30

First Bad Version

1.31 and above, up to 1.43

Steps to reproduce

Browser: Firefox

1. Clone repository https://github.com/mikhail-shafigullin/pw-bug from branch playwright-43
2. npm install -> npx playwright install
3. npm run test:e2e:local for local and npm run test:e2e:ci in Github Actions
4. Some runs will be failed in parallel build

Expected behavior

All runs are successful.

Actual behavior

Some runs have an error that they didn't find option button. Some runs have an error that they didn't find text in select after click on option.
Test Run: https://github.com/mikhail-shafigullin/pw-bug/actions/runs/8722579714

Additional context

This issue is a copy of issue on Playwright 1.41: #29096
My repository is a copy of the repository of topic starter from this issue.
Repository: https://github.com/mikhail-shafigullin/pw-bug

Environment

System:
    OS: macOS 13.5.2
    CPU: (10) arm64 Apple M1 Pro
    Memory: 58.45 MB / 32.00 GB
  Binaries:
    Node: 20.11.0 - ~/.nvm/versions/node/v20.11.0/bin/node
    Yarn: 1.22.19 - /usr/local/bin/yarn
    npm: 10.2.4 - ~/.nvm/versions/node/v20.11.0/bin/npm
  Languages:
    Bash: 3.2.57 - /bin/bash
  npmPackages:
    @playwright/test: 1.43.0 => 1.43.0

[yury-s]

сс @aslushnikov

[aslushnikov]

Indeed I can easily repro!

Turns out Juggler's focused page emulation is faulty and lets tabs to blur.

The reproduction:

import { firefox } from '@playwright/test';

const browser = await firefox.launch({
  executablePath: process.env.FFPATH,
  headless: false
});

async function run(id, page) {
  console.log('start', id);
  for (let i = 0; i < 10; i++) {
    await page.locator('.multiselect__select').click();
    await page.locator('li.multiselect__element').filter({ hasText: 'Option 3' }).click();
  }
  console.log('done', id);
}

const page1 = await browser.newPage();
await page1.goto('https://ilia-krivonosov.github.io/dropdown/');
const page2 = await browser.newPage();
await page2.goto('https://ilia-krivonosov.github.io/dropdown/');

await Promise.all([
  run('page1', page1),
  run('page2', page2),
]);
await browser.close();

[mikhail-shafigullin]

@dgozman Hello
Is it fixed? Will it be in the next playwright release?