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

Selenium

https://pypi.org/project/selenium/

Chai

https://www.chaijs.com
Programming language

Python

JavaScript

Category

Web Automation

Unit Testing

General info

Selenium is an open source tool used to test web applications

Selenium is a powerful testing tool which can send standard Python commands to different browsers, despite variations in browser design. It also provides extensions to emulate user interaction with browsers, a distribution server for scaling browser allocation, and the infrastructure for implementations of the W3C WebDriver specification that lets you write interchangeable code for all major web browsers

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

It is primarily a browser automation tool which tests front-end components and functionality

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

It can perform Unit tests and can test various components and behaviours in the backend using a BDD or TDD approach

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

By writing your Selenium WebDriver tests in PyTest, this gives you access to Pytest's powerful fixture model

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

One can group fixtures if accessing Pytest's fixture model

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.

Yes

By using a library such as Faker or Fake-factory

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

It includes support for mocking

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

By using the TestNG feature with which we can create groups and maintain them easily

N/A

Other
Other useful information about the testing framework