Kotest vs Chai comparison of testing frameworks
What are the differences between Kotest and Chai?

Kotest

https://github.com/kotest/kotest

Chai

https://www.chaijs.com
Programming language

Kotlin

JavaScript

Category

Unit Testing

Unit Testing

General info

kotest is a powerful, elegant and flexible test framework for Kotlin, formerly known as kotlintest

Kotest has excellent support for data driven testing or table driven testing where it has the ability to quickly rerun the same test over and over with a predefined set of inputs and expected values

Chai is a BDD / TDD assertion library for Node.js and the browser that can be paired with any JavaScript testing framework.

Chai is an assertion library, similar to Node's built-in assert and makes testing easier by giving you many assertions you can run against your code. It also includes a robust Plugin architecture for extending Chai's assertions and interfaces.
xUnit
Set of frameworks originating from SUnit (Smalltalk's testing framework). They share similar structure and functionality.

No

N/A

Client-side
Allows testing code execution on the client, such as a web browser

Yes

You can test front-end components with kotest

Yes

Chai can be used in a browser environment to test front-end components and functionality
Server-side
Allows testing the bahovior of a server-side code

Yes

Yes, you can test back-end components with kotest

Yes

Chai is used in a Node.JS environment to test server behaviour and functionality
Fixtures
Allows defining a fixed, specific states of data (fixtures) that are test-local. This ensures specific environment for a single test

Yes

kotest contains fixtures, that is the setup / teardown functions

N/A

Group fixtures
Allows defining a fixed, specific states of data for a group of tests (group-fixtures). This ensures specific environment for a given group of tests.

Yes

kotest has group fixtures available

N/A

Generators
Supports data generators for tests. Data generators generate input data for test. The test is then run for each input data produced in this way.

N/A

Yes

By using chai-spec-generator plugin which will generate chai test specs from a JavaScript object
Licence
Licence type governing the use and redistribution of the software

Apache License 2.0

MIT License

Mocks
Mocks are objects that simulate the behavior of real objects. Using mocks allows testing some part of the code in isolation (with other parts mocked when needed)

Yes

You can use a third party library like mockk to create mocks

Yes

By using by using a third party library like chai-jest-mocks which is a chai plugin that adds assertions for jest mock functions. You can also use sinon.js
Grouping
Allows organizing tests in groups

Yes

You can create test suites with kotest

N/A

Other
Other useful information about the testing framework