Magento Layered Architecture
Unit tests are designed to test individual class methods in isolation, asserting all possible combinations and taking care of the smallest testable part of an application.
Integration tests test the interaction between individual components, layers, and an environment.
Static tests do not really run the code; they analyze it. They are used to verify that the code conforms to certain coding standards
Integrity tests check how an application is linked. They check for things such as merged configuration validation. Basically, they tell us if your application should be able to run.
Functional tests mimic the user interaction with our application. They literally mean testing in the form of browser interaction, which involves clicking on the page, adding products to the cart, and so on.
Books
https://learning.oreilly.com/library/view/magento-2-development/9781789343441/
