Jest (just) in Five Minutes

• What is Jest?
• Jest is a JavaScript testing framework maintained by Facebook, Inc.

• How to set up Jest?
• https://jestjs.io/docs/en/getting-started

• Any easy tip to remember the syntactical steps of what you do when you write a test?
• DIE Matchers (Describe the Test(It) that Expects the result to Match the expectation)

• How does Jest supports mocking?
• jest.fn - allows you to mock a function. All mock functions have this '.mock' property.
• jest.mock - allows you to mock a module (module is the JavaScript module that was exported using module.exports or export default)
• jest.spyOn - allows you to mock either the whole module or the individual functions of the module. At its most general usage, it can be used to track calls on a method (read this nice article: https://blog.echobind.com/how-to-mock-using-jest-spyon-d13d57a8434d)
• NOTE: you can't spy something that doesn't exist on the object.

• How does the mock functions help you in the testing?
• Mock functions allow you to test the links between code by erasing the actual implementation of a function, capturing calls to the function (and the parameters passed in those calls), capturing instances of constructor functions when instantiated with new, and allowing test-time configuration of return values. Read more: https://jestjs.io/docs/en/mock-functions

• How do I mock an API call using Jest? Well, thanks to this blog given below...
• https://dev.to/zaklaughton/the-only-3-steps-you-need-to-mock-an-api-call-in-jest-39mb

• What is React-Testing-Library (RTL)?  
• RTL is a light-weight solution for testing react components. Unlike Enzyme, React will test DOM nodes instead of component instances.
• https://testing-library.com/docs/react-testing-library/intro/
• https://blog.echobind.com/writing-functional-tests-with-react-testing-library-part-1-470870ee1a6

What if I try here to cover a little bit on Jasmine?

• How does Jasmine supports mocking?
• jasmine.createSpy - to mock a function
• jasmine.createSpyObj - to mock a module
• jasmine.spyOn - to mock the individual functions of the module