I wrote front-end testing code less frequently. I heard a lot of frameworks used by my colleagues, like Karma, Jasmine, Chai, Mocha, Jest. you name it.

Why so much complex?

In the Java ecosystem, we have JUnit for the test runner, it provides test suites and all kinds of assert expressions. If we need to mock some dependencies, we use Mokito or others like. That’s enough.

So when it comes to Javascript, I am really confused with so many frameworks/libraries. What is worse is I don’t know their roles only from their name.

So the following I give a one sentence introduction for each of them.

• Karma: spectacular test runner for JavaScript that allows you to execute JavaScript code in multiple real browsers.
• Chai: a BDD / TDD assertion library for node and the browser
• Jasmine: a a Behaviour Driven Development testing framework for JavaScript
• Mocha: simple, flexible, fun javascript test framework
• Jest: another javascript test framework developed by Facebook

So obviously, Jasmine/Mocha/Jest can be of the similar role with some overlays.

Look at them a bit more

Jasmine

Jasmine provides with everything you are expected to need for your tests: a running environment, structure, reporting, assertion, and mocking tools. Has widespread Angular support.

One word: ready-to-go

Mocha

Mocha is usually used with third party assertion, mocking, and spying tools (usually Enzyme and Chai).

One word: flexible and extensible

Jest

Like Jasmine, everything is there.

One word: performance

See more in A complete guide to testing Javascript in 2017