How to enable parallel tests with puppeteer?

Question

I am using the chrome puppeteer library directly to run browser integration tests. I have a few tests written now in individual files. Is there a way run them in parallel? What is the best way to achieve this?

Answer 1

To run puppeteer instances in parallel you can check out this library I wrote: puppeteer-cluster

It helps to run different puppeteer tasks in parallel in multiple browsers, contexts or pages and takes care of errors and browser crashes. Here is a minimal example:

const { Cluster } = require('puppeteer-cluster');

(async () => {
  const cluster = await Cluster.launch({
    concurrency: Cluster.CONCURRENCY_CONTEXT, // use one browser per worker
    maxConcurrency: 4, // cluster with four workers
  });

  // Define a task to be executed for your data
  cluster.task(async ({ page, data: url }) => {
    await page.goto(url);
    const screen = await page.screenshot();
    // ...
  });

  // Queue URLs
  cluster.queue('http://www.google.com/');
  cluster.queue('http://www.wikipedia.org/');
  // ...

  // Wait for cluster to idle and close it
  await cluster.idle();
  await cluster.close();
})();

You can also queue your functions directly like this:

  const cluster = await Cluster.launch(...);

  cluster.queue(async ({ page }) => {
    await page.goto('http://www.wikipedia.org');
    await page.screenshot({path: 'wikipedia.png'});
  });

  cluster.queue(async ({ page }) => {
    await page.goto('https://www.google.com/');
    const pageTitle = await page.evaluate(() => document.title);
    // ...
  });

  cluster.queue(async ({ page }) => {
    await page.goto('https://www.example.com/');
    // ...
  });