Playwright

Installing browsers for playwright under NixOS

Normally, at first run, playwright will tell you to run playwright install. The purpose of this is to install browsers for you that it can then use for testing. The installation itself will technically work. Unfortunately, the installed browsers will not be suitable to be used inside NixOS. This is due to the fact that dependencies will not be at places where the browsers expect them to be. To mitigate this problem, nixpkgs has a package called playwright-driver.browsers. Before you start your script, make sure to set

export PLAYWRIGHT_BROWSERS_PATH=/path/to/drivers

You can for example put this shell.nix in the directory with your playwright-related code:

{ pkgs ? import <nixpkgs> {} }:
  pkgs.mkShell {
    nativeBuildInputs = [
      pkgs.playwright-driver.browsers
    ];

    shellHook = ''
      export PLAYWRIGHT_BROWSERS_PATH=${pkgs.playwright-driver.browsers}
      export PLAYWRIGHT_SKIP_VALIDATE_HOST_REQUIREMENTS=true
    '';
}

Playwright with Visual Studio Code

If you are using playwright with Visual Studio Code, you may want to add vscode to the package list shown earlier. With Visual Studio Code installed you can run nix-shell --run "code ." to open your playwright-related directory.

Don't forget to install the Playwright Test for VSCode extension in Visual Studio Code.

Then you should be able to run your tests in Visual Studio Code.

Note: Keep in mind that you need to use the same version of playwright in your node playwright project as in your nixpkgs, or else playwright will try to use browsers versions that aren't installed!

Playwright with Devenv

With Devenv you can also set certain environment variables and pin packages to make playwright work. Again, make sure to pin to the same version of playwright in devenv.yaml and package.json!

devenv.nix

{ pkgs, lib, config, inputs, ... }:

let
  pkgs-playwright = import inputs.nixpkgs-playwright { system = pkgs.stdenv.system; };
  browsers = (builtins.fromJSON (builtins.readFile "${pkgs-playwright.playwright-driver}/browsers.json")).browsers;
  chromium-rev = (builtins.head (builtins.filter (x: x.name == "chromium") browsers)).revision;
in
{
  # https://devenv.sh/basics/
  env = {
    PLAYWRIGHT_BROWSERS_PATH = "${pkgs-playwright.playwright.browsers}";
    PLAYWRIGHT_SKIP_VALIDATE_HOST_REQUIREMENTS = true;
    PLAYWRIGHT_NODEJS_PATH = "${pkgs.nodejs}/bin/node";
    PLAYWRIGHT_LAUNCH_OPTIONS_EXECUTABLE_PATH = "${pkgs-playwright.playwright.browsers}/chromium-${chromium-rev}/chrome-linux/chrome";
  };

  # https://devenv.sh/packages/
  packages = with pkgs; [
    just
    nodejs
  ];

  # https://devenv.sh/languages/
  languages.javascript.enable = true;

  dotenv.disableHint = true;
  cachix.enable = false;

  # https://devenv.sh/scripts/
  scripts.intro.exec = ''
    playwrightNpmVersion="$(npm view ./. devDependencies'[@playwright/test]')"
    echo "❄️ Playwright nix version: ${pkgs-playwright.playwright.version}"
    echo "📦 Playwright npm version: $playwrightNpmVersion"

    if [ "${pkgs-playwright.playwright.version}" != "$playwrightNpmVersion" ]; then
        echo "❌ Playwright versions in nix (in devenv.yaml) and npm (in package.json) are not the same! Please adapt the configuration."
    else
        echo "✅ Playwright versions in nix and npm are the same"
    fi

    echo
    env | grep ^PLAYWRIGHT
  '';

  enterShell = ''
    intro
  '';

  # See full reference at https://devenv.sh/reference/options/
}

devenv.yaml

# yaml-language-server: $schema=https://devenv.sh/devenv.schema.json
inputs:
  nixpkgs:
    url: github:NixOS/nixpkgs/nixos-unstable
  # Currently pinned to: playwright@1.52.0
  # See https://search.nixos.org/packages?channel=unstable&from=0&size=50&sort=relevance&type=packages&query=playwright
  nixpkgs-playwright:
      url: github:NixOS/nixpkgs/979daf34c8cacebcd917d540070b52a3c2b9b16e

package.json

{
  "name": "e2e-tests-ng",
  "version": "1.0.0",
  "main": "index.js",
  "license": "MIT",
  "devDependencies": {
    "@playwright/test": "1.52.0",
    "eslint": "^8.41.0"
  },
  "engines": {
    "node": ">=18.0.0"
  },
  "scripts": {
    "playwright:test": "playwright test",
    "playwright:test:ui": "playwright test --ui",
    "playwright:install": "playwright install",
    "lint": "eslint ."
  },
  "dependencies": {
    "dotenv": "^16.0.3",
    "jsrsasign": "^11.0.0"
  }
}

Playwright via Docker

https://playwright.dev/docs/docker#remote-connection can be a good option to make use of a container (instead of wrestling with NixOS) to run browsers.

# devenv.nix example that simplifies the configuration 
# but it's easy to setup the env var and run the command manually without devenv too

{
  env.PW_TEST_CONNECT_WS_ENDPOINT = "ws://127.0.0.1:3000/";

  # run it with `devenv processes up` and in another terminal run `npm exec playwright test` 
  processes.pw-remote.exec = "docker run -p 3000:3000 --rm --init --workdir /home/pwuser --user pwuser mcr.microsoft.com/playwright:v1.52.0-noble /bin/sh -c 'npx -y playwright@1.52.0 run-server --port 3000 --host 0.0.0.0'";
}

Will need a slight tweak like below for the IP address due to a small limitation comes with the container use.

// example.spec.ts

import { test, expect } from '@playwright/test';

test('has title', async ({ page }) => {
  // await page.goto('http://localhost:3333/'); // can't do due to the browsers running within a container but your server is running on the host
  await page.goto('http://host.docker.internal:3333/'); // so do this instead
  // also make sure your server code runs for playwright, too - https://playwright.dev/docs/test-webserver#configuring-a-web-server

  await expect(page).toHaveTitle(/your website/);
});