Answer

Generating TypeScript Code Coverage with Playwright and Monocart

First, ensure you've installed Playwright and Monocart. Next, create a tsconfig.json file in your tests directory. Here's a sample configuration:

{
  "compilerOptions": {
    "target": "ESNext",
    "module": "commonjs",
    "moduleResolution": "Node",
    "sourceMap": true,
    "outDir": "../tests-out"
  }
}

Then, add pretest and test scripts to your package.json file:

{
  "scripts": {
    "pretest": "tsc --incremental -p tests/tsconfig.json",
    "test": "<command to run playwright test>"
  }
}

Replace <command to run playwright test> with your project's specific command. Now, you can build and run your tests with npm run test.

To generate a code coverage report, use Playwright's Coverage API. It collects data about the JavaScript and CSS used by the page during testing. Here's an example of how to use JavaScript coverage to produce an Istanbul report:

const { chromium } = require('playwright');
const v8toIstanbul = require('v8-to-istanbul');

(async () => {
  const browser = await chromium.launch();
  const page = await browser.newPage();

  await page.coverage.startJSCoverage();
  await page.goto('https://ray.run'); // Replace with your test URL

  const coverage = await page.coverage.stopJSCoverage();

  for (const entry of coverage) {
    const converter = v8toIstanbul('', 0, { source: entry.source });
    await converter.load();
    converter.applyCoverage(entry.functions);
    console.log(JSON.stringify(converter.toIstanbul()));
  }

  await browser.close();
})();

In this example, we launch a Chromium browser, create a new page, start JavaScript coverage, navigate to the URL, and stop the coverage. We then convert the coverage data into an Istanbul report format using v8-to-istanbul. You can customize this report to fit your needs.

Remember, this assumes you've already set up Playwright and Monocart and have a basic understanding of TypeScript and code coverage concepts.