Q101. What is Shallow Renderer in React testing?
_Shallow rendering_ is useful for writing unit test cases in React. It lets you render a component _one level deep_ and assert facts about what its render method returns,...
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Q102. What is `TestRenderer` package in React?
This package provides a renderer that can be used to render components to pure JavaScript objects, without depending on the DOM or a native mobile environment. This packa...
Q103. What is the purpose of ReactTestUtils package?
_ReactTestUtils_ are provided in the `with-addons` package and allow you to perform actions against a simulated DOM for the purpose of unit testing.
Q104. What is Jest?
_Jest_ is a JavaScript unit testing framework created by Facebook based on Jasmine and provides automated mock creation and a `jsdom` environment. It's often used for tes...
Q105. What are the advantages of Jest over Jasmine?
There are couple of advantages compared to Jasmine: - Automatically finds tests to execute in your source code. - Automatically mocks dependencies when running your tests...
Q106. Give a simple example of Jest test case
Let's write a test for a function that adds two numbers in `sum.js` file: ```javascript const sum = (a, b) => a + b; export default sum; ``` Create a file named `sum.test...
Q107. What is flux?
**Flux** is an **application architecture** (not a framework or library) designed by Facebook to manage **data flow** in React applications. It was created as an alternat...
Q108. What is Redux?
Redux is a predictable state container for JavaScript applications, most commonly used with React. It helps you manage and centralize your application’s state in a single...
Q109. What are the core principles of Redux?
Redux follows three fundamental principles: 1. **Single source of truth:** The state of your whole application is stored in an object tree within a single store. The sing...
Q110. What are the downsides of Redux compared to Flux?
While Redux offers a powerful and predictable state management solution, it comes with a few trade-offs when compared to Flux. These include: 1. **Immutability is essenti...