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

	PHPUnit https://phpunit.de/	Chai https://www.chaijs.com
Programming language	PHP	JavaScript
Category	Unit Testing	Unit Testing
General info	PHPUnit is a unit testing framework for the PHP programming language PHPUnit is a programmer-oriented testing framework and is an instance of the xUnit architecture for unit testing frameworks.	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.	Yes It's an instance of the xUnit architecture for unit testing frameworks	N/A
Client-side Allows testing code execution on the client, such as a web browser	Yes It can perform Unit tests and can test various front-end components and behaviours	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 By performing unit tests on singular back-end components	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 use of a setup code. The setup code consists of two Important template functions, the 'setUp()' function (called to create the objects to be tested) and 'tearDown()' function (called to cleanup the objects which you tested)	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 It does support group fixtures	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	Creative Commons Attribution 3.0 Unported License	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 One of its main features is that PHPUnit comes with out of the box support for Mock objects	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 It allows grouping of tests and by using the @group annotation one can tag a test to belong to one or more groups	N/A
Other Other useful information about the testing framework