Answer

Creating a Custom Selector Engine in Playwright

Creating a custom selector engine in Playwright involves a few steps.

Registering the Selector Engine

First, you need to register your custom selector engine using the selectors.register() method. This method requires a create function, a query function, and a queryAll function.

Here's an example of how to register a custom engine that queries elements based on their tag name:

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

const createTagNameEngine = () => ({
  query(root: Document | ShadowRoot | Element, selector: string) {
    return root.querySelector(selector);
  },
  queryAll(root: Document | ShadowRoot | Element, selector: string) {
    return Array.from(root.querySelectorAll(selector));
  },
});

await selectors.register('tag', createTagNameEngine);

Using the Custom Selector Engine

Once registered, you can use your custom selector engine by prefixing the selector with its name. For example:

const button = page.locator('tag=button');

You can also combine your custom selectors with built-in locators and use them in any methods that support selectors. For example:

await page.locator('tag=div').getByText('Click me').click();

And you can perform assertions on elements selected using your custom engine:

await expect(page.locator('tag=button')).toHaveCount(3);

Remember to register your selectors before creating any pages in Playwright. For more details, check out Mastering Playwright Test Automation: Your Comprehensive Cheat Sheet.