ChromeHeadless can’t run as root with –no-sandbox anymore in Karma Runner Karma

Explanation of the problem

25 10 2017 08:47:40.197:ERROR [launcher]: Cannot start ChromeHeadless
[1025/084740.006078:ERROR:zygote_host_impl_linux.cc(88)] Running as root without --no-sandbox is not supported. See https://crbug.com/638180.

This issue is observed in a Docker environment running Ubuntu 16.

The error message suggests that ChromeHeadless cannot be started due to a compatibility issue with the version of Chromedriver being used. Specifically, the error states that running Chrome as root without the “–no-sandbox” flag is not supported, as detailed in the link provided in the error message (https://crbug.com/638180).

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Problem solution for ChromeHeadless can’t run as root with –no-sandbox anymore in Karma Runner Karma

const puppeteer = require('puppeteer');
const browser = await puppeteer.launch({headless: true, args:['--no-sandbox']});

Other popular problems with Karma

//example of karma.conf.js
module.exports = function(config) {
  config.set({
    files: [
      'src/**/*.js', //this is the pattern for source files
      'test/**/*.spec.js' //this is the pattern for test files
    ],
    frameworks: ['jasmine'],
    preprocessors: {
      'src/**/*.js': ['babel'],
      'test/**/*.spec.js': ['babel']
    },
    //...
  });
};

Problem: Tests are failing with a timeout

Another common problem with Karma is that tests are failing with a timeout error. This can happen when tests are taking too long to complete or when there is a problem with the test runner’s communication with the browser.

Solution:

To solve this problem, you can increase the timeout value in the Karma configuration file or you can fix the problem by looking into the browser’s console for error messages and fix them.

//example of karma.conf.js
module.exports = function(config) {
  config.set({
    //...
    browserNoActivityTimeout: 60000, //increase the timeout value to 60 seconds
    //...
  });
};

Problem: Tests are failing with a “Cannot read property ‘xxx’ of undefined” error

Another common problem with Karma is that tests are failing with a “Cannot read property ‘xxx’ of undefined” error. This error happens when the test is trying to access a property of an object that is undefined. This can happen when an object is not defined or when a module is not imported correctly.

Solution:

To solve this problem, you should check that all the required modules are imported correctly and that objects are defined before they are used in the test.

//example of test file
import { MyObject } from './myObject';

describe('MyObject', () => {
  it('should have a property x', () => {
    const obj = new MyObject();
    expect(obj.x).toBeDefined();
  });
});

//example of myObject.js
export class MyObject {
  constructor() {
    this.x = 'some value';
  }
}

A brief introduction to Karma

Karma is a test runner for JavaScript that can be used to run tests for web applications. It is designed to work with a variety of testing frameworks, such as Jasmine, Mocha, and Protractor. Karma uses a browser-based test runner to execute tests, which allows you to run tests in multiple browsers and on different platforms. This allows you to test your web application in a variety of environments and ensure that it works as expected.

Karma is highly configurable and can be integrated with a variety of build tools, such as Grunt, Gulp, and Webpack. It also has a plugin system that allows you to add additional functionality, such as code coverage reporting, test reporting, and test watch mode. Karma also provides an API that allows you to interact with the test runner programmatically, which can be useful for automating testing tasks. Overall, Karma is a powerful tool that can help you test your web application and ensure that it is working correctly.

Most popular use cases for Karma

describe('MyFunction', () => {
  it('should return the correct value', () => {
    expect(MyFunction()).toEqual('some value');
  });
});