React Applications are made up of different components, frameworks, or features, which is why testing is necessary to ensure all parts work as they should.
In this case, one of the most robust, albeit time-consuming forms of software testing is End-to-end testing because it focuses on testing all aspects of a React application to ensure that every feature works as expected.
Various testing tools, such as Cypress.io, Mocha, Enzyme, and many others, are used for running end-to-end tests. However, this article is centered on conducting an End-to-end test for React apps using Jest as the testing tool.
In software development, end-to-end testing is a vital component that ensures the application functions properly in a real-world setting and that the different parts of a system interact as intended.
End-to-end testing is significant when developing React apps since they often comprise several separate components and frameworks.
Jest is widely regarded as a top tool for conducting end-to-end testing of React applications.Jest is a robust testing framework that can write and implement automated tests for React apps.
In our previous article, we went in-depth into understanding the concept of
End-to-end testingand why it is vital for producing highly effective applications.
However, this article will cover the primary steps for conducting an end-to-end test for React apps using Jest.
To get started, let us better understand End-to-end testing and Jest.
What is End-to-End Testing?
End-to-end testing is another software test that examines the entire system from end to end. This testing ensures that all system components interact correctly and function as expected in a real-world environment.
At
Fetchly Labs, we prioritize testing various parts of an application after it has been created to ensure it works as it should. But when carrying out End-to-end testing, the focus is on the entire system rather than individual elements.
End-to-end testing also allows developers at Fetchly to identify issues that may exist across multiple layers of an application, such as the front-end, back-end, and database. By running tests that simulate real-world user interactions, end-to-end testing can help developers catch issues early in the development stage before they become more complicated and expensive to repair.
What is Jest?
Jest is an open-source JavaScript testing framework developed and managed by Facebook. It was designed to test React apps but can also be utilized to test other JavaScript application forms. Jest is a robust framework that allows developers to write and execute automated tests quickly and easily.
Testing a React Application
Effectively carrying out an End-to-end test for a React app using Jest requires three significant steps, namely:
- Setting up Jest in preparation for the test.
- Writing the tests with Jest.
- Running the test
Setting up Jest
Before using Jest to conduct an end-to-end test for a React app, you must set it up. Setting up Jest is a relatively simple process. If you used create-react-app to bootstrap your application, Jest is already included straight from the box. If your stack is custom-built, however, you can install it via npm using the following:
npm install Jest
Then, initialize a jest configuration file using the instructions laid out by Jest afterward:
npx jest --init
Once Jest has been set up, you can move on to writing tests.
Writing Tests with Jest
Once Jest has been set up, you can start writing tests for your React app. Jest has a variety of features that make it easy to write tests. The "test" function is an essential feature that defines Jest.
The "test" function takes two arguments: a string that describes the expected feature to be tested and a function argument that contains the test logic. For example, suppose you wanted to test a React component; in that case, you could write the following code:
test('MyComponent renders correctly', () => {
const component = shallow(<MyComponent />);
expect(component).toMatchSnapshot();
});
This code will test that the component renders correctly. If the component does not render correctly, the test will fail. To fulfill the concept of End-to-end testing, however, you want to write tests for your application's features and use cases.
In addition to the "test" function, Jest provides several other useful features. For example, you can use the "beforeEach" and "afterEach" functions to build up and tear down test data before and after each test. You can also use the "expect" assertion to check that certain conditions are met.
Finally, you can use the "describe" function to group related tests.
Running Tests
Once you have successfully written your tests, you can run them using the Jest command line.
Use the following command line to run the test:
npm run test
Jest will run all the tests and display the results in the command line.
Final Thoughts
This article centers on how to conduct end-to-end testing for React apps using Jest. We also discussed setting up Jest, writing tests with Jest, and running tests with Jest, as these are all essential aspects of the testing process.
Developing a web and mobile application requires paying close attention to how it looks and functions, so the process cannot be rushed.
When developers carry out an end-to-end test at Fetchly, they take their time with the process while working with the QA department to conduct in-depth simulations of how every application component should work within a web or mobile application.
That being said, the ultimate success of a new application in the digital market largely depends on the end user's experience, making it essential to prioritize software testing in its various forms.
*This is not the official Fetchly opinion but the opinion of the writer who is employed by Fetchly*
