Learn how to test React app with Jest and Selenium.

Mastering Selenium

This module will teach us to properly test our React applications, starting from basic unit tests with Jest to automated integration tests using Selenium. We’ll learn everything from the ground up to the most advanced concepts, and gain confidence in shipping our software to customers.

Test React Applications with Jest and Selenium

Now that you have a basic idea of testing, let's explore why testing is so important when developing a production application.

It is easy to overlook the role of testing when starting a new project. While it is relatively small, it is quite easy (and sometimes faster) to test it manually. However, as the project grows, manual testing becomes infeasible.

## The power of knowing

Testing gives you the power of _knowing_. With a comprehensive test suite in place, you can instantly check if your changes broke anything else in the app.

How many times did you refactor a piece of code and then found out that something completely unrelated stopped working? Or how many times have you read through thousands of lines of code to find out which modules use this particular function?

Testing makes refactoring a piece of cake. You can change anything without fearing that the change will result in unwanted consequences. This will accelerate the development process immensely. Suddenly, the refactoring efforts are kept to a minimum and the backlog will be cleared before you know it.

## Code cleanliness

While writing code without tests, the design specifications are translated directly to the production code. When following TDD, there is an intermediate step. You first translate the specifications into tests, and write production code to follow the tests.



Now that you have a basic idea of testing, let's explore why testing is so important when developing a production application.

It is easy to overlook the role of testing when starting a new project. While it is relatively small, it is quite easy (and sometimes faster) to test it manually. However, as the project grows, manual testing becomes infeasible.

# The power of knowing

Testing gives you the power of _knowing_. With a comprehensive test suite in place, you can instantly check if your changes broke anything else in the app.

How many times did you refactor a piece of code and then found out that something completely unrelated stopped working? Or how many times have you read through thousands of lines of code to find out which modules use this particular function?

Testing makes refactoring a piece of cake. You can change anything without fearing that the change will result in unwanted consequences. This will accelerate the development process immensely. Suddenly, the refactoring efforts are kept to a minimum and the backlog will be cleared before you know it.

# Code cleanliness

While writing code without tests, the design specifications are translated directly to the production code. When following TDD, there is an intermediate step. You first translate the specifications into tests, and write production code to follow the tests.



Learn about the importance of testing and the way it solves common problems in the development world.

Introduction

Introductory Quiz

Write Your First Tests

Basic Testing Exercises

More Tests

Mocking Modules in Unit Tests

Mocking Exercises

More on Integration Tests

Bonus: Custom Matchers

Conclusion

Significance of Testing

The power of knowing