Tutorials on Testing

The newline Guide to Storybook for Building React Apps is coming soon (May 2022). 🎉

Testing is basically a requirement for modern software today, not a nice-to-have. In the past, end-to-end testing was hard to set up, flaky, and generally a pain to deal with, but it's the best automated testing option to confirm software works. Cypress.io continues to improve the e2e testing experience and its new feature Cypress Studio takes it a step further to make writing tests quicker and easier too.

Disclaimer - If you are unfamiliar with writing a simple unit test for a route handler of a Go and chi RESTful API, then please read this blog post before proceeding on. Go's testing library package provides many utilities for automating the testing of Go code. To write robust tests for Go code, you must already understand how to write a basic Go test suite that contains several TestXxx functions. Writing tests for code, especially within the context of test-driven development (TDD), prioritizes the code's correctness over the code's flexibility to adapt to new/updated requirements. The guarantee of less unexpected regressions offsets the upfront cost of spending more time to write tests alongside application code. In a fast-paced, high-pressure environment, it can be difficult to convince other team members and stakeholders of the value in testing code when time is an extremely limited resource. Another factor that must be considered is the amount of code covered by the tests. If the tests cover only a small percentage of the application code (or a small subset of use cases), then the benefits of having these tests probably won't outweigh the benefits of adding new features or improving existing features. Plus, anytime you decide to refactor the application code, you will also have to update the corresponding tests to reflect these changes. When time is so valuable, the time spent on writing tests could have been spent elsewhere. Therefore, to fully benefit from tests, you must write enough tests such that they cover a large percentage of the application code.

In previous posts we learned: In this post, we're going to write tests for a custom React hook. We're going to create a custom hook that will uppercase a given text string. This hook will be connected to an input and whenever a user changes the input value this hook will automatically uppercase the value.

Testing plays a fundamental role in the development of quality software. Shipping and deploying software with undetected bugs and regressions opens up a can of terrible consequences such as losing the trust of end users or costing the business time and resources. In a large collaborative setting, having developers manually test each and every feature and user flow for bugs and regressions wastes valuable time that can be put towards improving other aspects of the software. As the codebase and team grows, this approach will not scale. By writing unit/integration/end-to-end tests, identifying and catching bugs and regressions throughout an entire codebase becomes a painless, automatable task that can easily be integrated into any continuous integration pipeline. Unlike most other languages, the Go programming language provides a built-in, standard library package for testing: testing . The testing package offers many utilities for automating the testing of Go source files. To write a test in Go, define a function with a name prefixed with Test (followed by a capitalized segment of text) and accepts an argument of struct type T , which contains methods for failing and skipping tests, running multiple tests in parallel, formatting test logs, etc. Example :

In the previous post , we created a unit test for a function. In this post, we're going to create a unit test for a component using @testing-library/react . Since we're using Create React App the React Testing Library is already installed in our dependencies. If you don't have it, install the package using: We will create a Greetings component with the greetings text inside and a button for sending friendly waves 😊

Tests make sure that changes in code don't break its functionality. For testing an app, we need a test runner. Create React App provides us a test runner called jest . Let's create a new app and inspect what it contains. The src directory contains all the app code and a file called App.test.tsx . This file contains a test that makes sure that the App component renders a link:

Hooks in React are a new, popular, and extensible way to organize side-effects and statefulness in React components. By composing the base hooks provided by React, developers can build their own custom hooks for use by others. Redux, ApolloClient, and Callstack have distributed custom hooks to access your app's store, client, and themes using the useContext hook. You can also compose useEffect and useState to wrap API requests or wrap the concept of time. It's powerful. It's simple. These two statements are not a coincidence, either: the power is the simplicity.