Galata tests: use webServer in the Playwright config to start JupyterLab

[jtpio]

Problem

Currently we need to start JupyterLab separately to run the Galata tests:

jupyterlab/.github/workflows/galata.yml

Lines 30 to 33 in 10c16e8

	- name: Launch JupyterLab
	run: |
	cd galata
	jlpm start 2>&1 > /tmp/jupyterlab_server.log &

And wait for it to be ready:

jupyterlab/.github/workflows/galata.yml

Lines 42 to 46 in 10c16e8

	- name: Wait for JupyterLab
	uses: ifaxity/wait-on-action@v1
	with:
	resource: http-get://localhost:8888/lab
	timeout: 360000

Proposed Solution

Playwright added support for starting web servers via the playwright.config.js in 1.24:

https://github.com/microsoft/playwright/releases/tag/v1.24.0

// playwright.config.ts
import type { PlaywrightTestConfig } from '@playwright/test';
const config: PlaywrightTestConfig = {
  webServer: [
    {
      command: 'npm run start',
      port: 3000,
      timeout: 120 * 1000,
      reuseExistingServer: !process.env.CI,
    },
    {
      command: 'npm run backend',
      port: 3333,
      timeout: 120 * 1000,
      reuseExistingServer: !process.env.CI,
    }
  ],
  use: {
    baseURL: 'http://localhost:3000/',
  },
};
export default config;

We could leverage this to streamline how the JupyterLab application is started for the UI tests. Playwright handles waiting for the application to be ready (port and url are configurable).

Additional context

Docs: https://playwright.dev/docs/test-advanced#launching-a-development-web-server-during-the-tests