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Karma vs WebdriverIO: What are the differences?


In the world of web development, two popular tools for testing web applications are Karma and WebdriverIO. While both of them serve the same purpose of testing web applications, there are some key differences between them that make each tool unique and suitable for different scenarios.

  1. Test Runner vs. Automation Framework: Karma is primarily a test runner, which means it executes tests in the browser environment. It focuses on running unit tests and provides features like test frameworks, test reporter, and code coverage. On the other hand, WebdriverIO is an automation framework that allows you to automate browser interactions and perform end-to-end testing. It provides a wide range of APIs for browser automation and supports various testing frameworks.

  2. Testing Levels: Karma is mainly suitable for unit testing, where it executes tests at a lower level, typically focusing on individual functions, modules, or units of code. It facilitates running tests in browsers and provides tools for testing JavaScript code. In contrast, WebdriverIO is more oriented towards end-to-end testing, where tests are executed at a higher level, simulating user interactions with the application in a real browser environment.

  3. Testing Scope: Karma is primarily designed for testing JavaScript code in isolation, allowing you to test individual components or modules in an isolated manner. It provides a clean sandboxed environment for testing. On the other hand, WebdriverIO allows you to test the entire web application as a whole, including interactions between different components and modules. It simulates real user interactions and validates the application's behavior as a complete system.

  4. Browser Compatibility: Karma supports multiple browsers, allowing you to run tests in various browser environments simultaneously or sequentially. It provides easy configuration for launching and controlling different browsers. In contrast, WebdriverIO supports a wide range of browsers through Selenium WebDriver or WebDriver protocol. It allows you to control browsers programmatically and perform cross-browser testing.

  5. Concurrency and Parallel Execution: Karma executes tests in a sequential manner, one after the other, by default. However, it also provides options for running tests concurrently in multiple browser instances. On the other hand, WebdriverIO supports parallel execution of tests out of the box. It can distribute the tests across multiple browser instances, enabling faster and efficient test execution.

  6. Community and Ecosystem: Karma has been around for a longer time and has a larger user base and community support. It has a well-established ecosystem with a wide range of plugins, frameworks, and tools integrated with it. WebdriverIO, although relatively newer, also has a growing community and ecosystem. It provides extensive documentation, integrations with various frameworks, and plugins for enhancing the testing capabilities.

In summary, Karma is a test runner focused on unit testing JavaScript code in browsers, while WebdriverIO is an automation framework tailored for end-to-end testing and browser automation. Karma is more suitable for isolated JavaScript testing, whereas WebdriverIO is ideal for simulating user interactions and testing the complete web application. The choice between the two depends on the testing requirements and the scope of the application being tested.

Advice on Karma and WebdriverIO
Needs advice

we are having one web application developed in Reacts.js. in the application, we have only 4 to 5 pages that we need to test. I am having experience in selenium with java. Please suggets which tool I should use. and why ............................ ............................ .............................

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Replies (1)
Prashanth Marappa
Senior Software Engineer at Mphasis · | 1 upvotes · 218.3K views

with the help of selenium we can automate react js for functional testing

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Needs advice

Hi, I am starting out to test an application that is currently being developed - FE: React. BE: Node JS. I want the framework to be able to test all UI scenarios (from simple to complex) and also have the capability to test APIs. I also need to run tests across all OSs and Browsers (Windows, Mac, Android, iOS). I have also looked into react-testing-library and Any advice you can give as to which framework would be best and why would be so much appreciated! Thank you!!

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Replies (3)

You should also definitely look into Playwright, which is a new automation tool from Microsoft building on top of the Puppeteer experience and trying to bring this experience in the cross browser space - very exciting project. Great team. Also CodeceptJS as already Playwright support which at a ton of valuable features on top of Playwright, give it a go!

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Jinesh Khimsaria
Test Automation Specialist at Personal · | 3 upvotes · 73.8K views

I'm also looking for the same, FE: React & BE: NodeJS. Cypress won't help as it lacks cross-browser testing, it doesn't support all the browsers. I'm still investigating it, but looks like WebdriverIO may fulfil what I'm looking for - Cross-browser testing, integration with CI/CD, running it as a docker service, good support on assertions & reporting of test results. Let me know if you found any information on any of the above mentioned points.

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Hi Esther, if you really need cross OS and cross device automation Cypress wont help, with WebdriverIO you can do it … and check out CodeceptJS, which is a wrapper around several frameworks (like WebdriverIO) and will support future players (currently for example upcoming Playwright) as well.

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Pros of Karma
Pros of WebdriverIO
  • 61
    Test Runner
  • 35
    Open source
  • 27
    Continuous Integration
  • 22
    Great for running tests
  • 18
    Test on Real Devices
  • 11
    Backed by google
  • 5
    Easy Debugging
  • 2
    Remote Control
  • 11
    Various integrations to vendors like Sauce Labs
  • 10
    Open Source
  • 8
    Great community
  • 7
    Easy to setup
  • 4
    Best solution for broad browser support

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Cons of Karma
Cons of WebdriverIO
  • 1
    Slow, because tests are run in a real browser
  • 1
    Requires the use of hacks to find tests dynamically
  • 8
    High maintenance

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What is Karma?

Karma is not a testing framework, nor an assertion library. Karma just launches a HTTP server, and generates the test runner HTML file you probably already know from your favourite testing framework. So for testing purposes you can use pretty much anything you like.

What is WebdriverIO?

WebdriverIO lets you control a browser or a mobile application with just a few lines of code. Your test code will look simple, concise and easy to read.

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What companies use Karma?
What companies use WebdriverIO?
See which teams inside your own company are using Karma or WebdriverIO.
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What tools integrate with Karma?
What tools integrate with WebdriverIO?

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What are some alternatives to Karma and WebdriverIO?
Jasmine is a Behavior Driven Development testing framework for JavaScript. It does not rely on browsers, DOM, or any JavaScript framework. Thus it's suited for websites, Node.js projects, or anywhere that JavaScript can run.
Jest provides you with multiple layers on top of Jasmine.
Mocha is a feature-rich JavaScript test framework running on node.js and the browser, making asynchronous testing simple and fun. Mocha tests run serially, allowing for flexible and accurate reporting, while mapping uncaught exceptions to the correct test cases.
Protractor is an end-to-end test framework for Angular and AngularJS applications. Protractor runs tests against your application running in a real browser, interacting with it as a user would.
JavaScript is most known as the scripting language for Web pages, but used in many non-browser environments as well such as node.js or Apache CouchDB. It is a prototype-based, multi-paradigm scripting language that is dynamic,and supports object-oriented, imperative, and functional programming styles.
See all alternatives