How to enable parallel tests with puppeteer?

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/');
    // ...
  });

How I achieved this was to create your suite(s) of tests in individual files, as you have done already. Then create a testSuiteRunner.js file (or whatever you wish to call it) and set it up as follows:

require('path/to/test/suite/1);
require('path/to/test/suite/2);
require('path/to/test/suite/3);
...

Import all of your suite(s) using require statements, like above, (no need to give them const variable names or anything like that) and then you can use node ./path/to/testSuiteRunner.js to execute all of your suites in parallel. Simplest solution I could come up with for this one!

I think the best idea would be to use a test runner like Jest that can manage that for you. At least I do that this way. Please keep in mind the machine might blow up if you'd run too many Chrome instances at the same time so it's safe to limit the number of parallel tests to 2 or so.

Unfortunately, it isn't clearly described in the official documentation of how Jest parallels the tests. You might find this https://github.com/facebook/jest/issues/6957 useful.

Libraries as puppeteer-cluster are great but remember first of all you want to parallel your tests, not puppeteer's tasks.