Then in all components in this sub-tree, you are able to get the data thanks to a Consumer. Conceptually, you will put data in a React context and provides it to a React sub-tree component thanks to a Provider. Import ParentDisplay from "./ParentDisplay" // mocking compan圜ontext's compan圜onsumer module for child components. Context provides a way to pass data through the component tree without having to pass props down manually at every level. In the file insert the following code: import React, from "./_mocks_/Compan圜ontextMock.js" To use it, you need two things: A provider. STEP 2: Create our React ContextAPI Provider and Consumer cd sample-test-app A curated list of stuff related to the new React Context API - GitHub - diegohaz/awesome-react-context: A curated list of stuff related to the new React. Reacts context API allows you to share data on a global level. Note, that this tutorial will not be using any external API calls. It will read employee data, create new employees, update employee data, and delete employees. We will solve this by using Jest to mock contextAPI. In this article, you will use Context API and React hooks together to build a fully functional CRUD application that emulates a list of employees. Given that there are no specific resources addressing it, I decided to share my solution through a simple application. The issue is that there is no provider defined in our ParentDisplay component therefore its child component (ChildCompanyDisplay) will have nothing to consume (note: The provider is defined in our main parent App component) A Portal is rendered outside of its parent DOM element but behaves in the application like any other React component. This feature was introduced in version 16.0 of React. How do we conduct ParentDisplay component unit testing to check whether values provided by contextAPI to child components are correctly rendered? React Portal is a method that renders child components into DOM nodes beyond the component tree hierarchy’s parent DOM hierarchy. You start with a top-level component that uses Context to store. This is exactly what we need for global state management. React describes context as: Context provides a way to pass data through the component tree without having to pass props down manually at every level. > ParentDisplay (no provider defined for children) Now, let’s explore what React Context is. Consider this Heading component that accepts a level for its size: App.js Section.js Heading.js App. Our React application will be structured this way: With React’s context feature, there is Context: an alternative to passing props Context lets a parent component provide data to the entire tree below it. We will create a basic application and demo how to mock a contextAPI provider and consumer for a component unit test. In this article we will discuss how to test and mock React ContextAPI using Jest and React Testing Library (React Testing Library).
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