
Cypress Nextjs is a powerful combination that can take your web development to the next level. Cypress is a fast, easy-to-use, and reliable testing framework that can be integrated with Nextjs, a popular React-based framework, to create seamless end-to-end testing experiences.
With Cypress Nextjs, you can write tests that interact with your application just like a real user would, checking for everything from form submissions to API calls. This means you can catch bugs and issues early on, saving you time and headaches down the line.
Nextjs provides a lot of built-in features that make it easy to integrate Cypress for end-to-end testing. For example, Nextjs provides a built-in API route for testing, which can be used to write tests that interact with your application's API.
Additional reading: Next Js Spa
Setting Up a Project
To set up a Next.js project with Cypress, create a new folder called "cypress" in the root directory of the project. This is the first step in getting started with Cypress for Next.js.
You'll also need to add the cypress script to the package.json file. This is where you'll configure Cypress to work with your Next.js project.
Start the test runner using the command "npx cypress run". This will open the Test Runner for Cypress, where you can run your tests.
The cypress folder will contain all your tests, making it easy to manage and organize your test suite.
Related reading: How to Run Nextjs to Build
Navigation
Navigation is crucial for any web application, and Next.js makes it a breeze with its powerful routing system.
You can easily create client-side and server-side routes using this system.
To test navigation in a Next.js application, use the cy.visit() command to navigate to different routes.
Writing assertions is also a good idea to check if the correct page has been loaded.
For example, to test if the About page has been loaded correctly, you can use the cy.visit() command to navigate to that page and then write an assertion to check if it's loaded.
Assertions can be written to check if the correct page has been loaded.
Explore further: Check Nextjs Version
Forms
Forms are an essential part of most web applications, and testing them is crucial to ensure that they function correctly.
To test forms in a Next.js application, you'll need to use the cy.get() command to locate form elements and the cy.type() command to simulate user input.
The cy.visit() command is used to visit the form page before filling in the form fields and clicking the submit button.
You can use the cy.get() command to find the form fields by their IDs, and then use the cy.type() command to fill in the data.
To check if a form is submitted correctly, you can use the cy.contains() command to check that the success message is displayed after submitting the form with valid data, and the error message is displayed after submitting the form with invalid data.
Here's a step-by-step guide on how to test a form in a Next.js application:
- Visit the form page using the cy.visit() command.
- Use the cy.get() command to find the form fields by their IDs.
- Fill in the form fields with test data using the cy.type() command.
- Click the submit button.
- Use the cy.contains() command to check if the success or error message is displayed.
Authentication
Authentication is a crucial aspect of many web applications, and testing it is necessary to ensure that users can log in and access protected resources. You can use Cypress to test authentication by making HTTP requests to the application's API endpoints.
To test if a user can log in successfully, you can use the cy.request() command to make a POST request to the /api/login endpoint with test user credentials. This will check if the response contains an access token.
You'll need to visit the login page before filling in the username and password fields and clicking the login button. You can use the cy.visit() command to do this. Then, use the cy.get() command to find the username and password fields by their IDs and fill in the data using the cy.type() command.
After submitting the form, you should check that the error message is displayed if the credentials are invalid, and the dashboard page is displayed if the credentials are valid. You can use the cy.contains() command to check for this.
Here's a breakdown of the steps involved in testing authentication:
- Visit the login page using cy.visit()
- Find the username and password fields using cy.get()
- Fill in the data using cy.type()
- Submit the form and check for the error message or dashboard page using cy.contains()
Effortless Coverage
Effortless Coverage is a game-changer for robust frontend applications. Learning multiple tools for unit, integration, and end-to-end testing can be time-consuming and overwhelming.
This is where component testing comes in, unifying unit and visual tests in a way that provides similar benefits and coverage as end-to-end testing, without the complex setup and maintenance.
With Cypress and Next.js, you can leverage component testing to achieve effortless coverage, making it easier to write and maintain tests for your web application.
Accessibility Tests with Scope
Accessibility tests with a component scope are crucial for ensuring that individual components are accessible and usable. This can be achieved by leveraging automated accessibility testing tools like cypress-axe.
To perform accessibility tests with a component scope, you can use the cy.injectAxe() command after visiting or mounting components and before calling cy.checkA11y(). This will prepare everything for accessibility testing.
The cy.checkA11y() command can be used to perform a range of accessibility checks, either on the current page or on a specified element. By default, it will run on the entire document, but you can pass in the component's selector to define the scope of the analysis.
Here are the key commands to use for accessibility testing with a component scope:
- cy.injectAxe() - injects axe on the page, preparing everything for accessibility testing
- cy.checkA11y() - performs a range of accessibility checks on the specified element
Make sure to call cy.injectAxe() after visiting or mounting components and before calling cy.checkA11y() to ensure accurate results. This will help you catch any accessibility issues specific to the component being tested.
Benefits of Using
Using Cypress with Next.js offers several benefits that make testing and development a breeze. Fast and reliable tests are just one of the many advantages of this powerful combination.
Cypress allows developers to write tests quickly and easily, thanks to its user-friendly interface and robust API. With Next.js providing server-side rendering, initial load times are faster, resulting in even faster tests.
Setting up a Next.js project with Cypress is a straightforward process. There are numerous online tutorials and guides that provide step-by-step instructions to get you started.
This testing library offers excellent documentation, complete with examples, tutorials, and best practices for writing tests. Whether you're a seasoned developer or just starting out, you'll find it easy to use Cypress with Next.js.
Here are some of the key benefits of using Cypress with Next.js:
- Fast and reliable tests
- Easy setup
- Excellent documentation
- Integration with CI/CD tools
With Cypress and Next.js, you can run tests automatically after each code deployment using tools like Jenkins, Travis, and CircleCI.
TypeScript Integration
TypeScript can be a bit finicky when working with Cypress, but don't worry, it's usually just a few tweaks away from playing nicely.
The first step is to add types to your root tsconfig.json file. This will help TypeScript understand the project's structure.
You may also need to add a tsconfig.json file to your cypress/ folder, which is a simple process of extending the base project file.
Adding 'plugin:cypress/recommended' to your eslint config is often the magic trick that solves most type issues with Cypress.
Here are the tweaks you'll need to make:
- add types to your root tsconfig.json
- add a tsconfig.json to cypress/
- add 'plugin:cypress/recommended' to your eslint config
Since this project uses CSS modules and SCSS, it needs to be suitably configured in the support file for component testing.
Testing
Testing is an essential part of building a robust and reliable application. You can run tests in Cypress to ensure your application is working as expected. With the Cypress app open, navigate to component testing and click on the filename themeToggle.cy.js to run the test.
A unique perspective: How to Run Next Js App
You can also use Cypress to test accessibility. Cypress-axe is a library that runs axe-core under the hood, which is an accessibility testing engine used to test apps against WCAG rules. To use it, you need to call cy.injectAxe() after visiting or mounting components and before calling cy.checkA11y(). This will help you identify and fix accessibility issues in your application.
Here are some key points to keep in mind when writing accessibility tests:
- cy.injectAxe() is used to inject axe on the page, preparing everything for accessibility testing
- cy.checkA11y() is used to perform a range of accessibility checks, either on the current page or on a specified element
It's also important to test the accessibility of your application in different scenarios, such as when switching to dark mode. This will help you ensure that your application remains accessible and usable for all users.
Installing
Installing Cypress is pretty straight-forward, you can install it using npm or yarn.
Make sure your machine is compatible with the Cypress system requirements.
To install Cypress, you can use npm: npm install cypress.
If you prefer yarn, you can install Cypress using: yarn add cypress.
Add the libraries as development dependencies to begin.
Make sure that cypress is at least version 10 or higher to get access to component testing.
Add scripts to your package.json that'll allow you to open Cypress, and to run your component tests headlessly.
Take a look at this: How to Add Img to Nextjs
Frequently Asked Questions
What is the difference between Nextjs playwright and Cypress?
Playwright outperforms Cypress in complex, multi-page applications, while Cypress excels in simple, JavaScript-focused projects. Choose Playwright for complex scenarios and Cypress for streamlined, JavaScript-centric development
Sources
- https://webkul.com/blog/cypress-integration-in-next-js/
- https://larsmagnus.co/blog/component-testing-with-cypress-in-next-js
- https://articles.readytowork.jp/boosting-next-js-performance-a-guide-to-e2e-and-component-testing-with-cypress-d696a45114ba
- https://buttercms.com/blog/how-to-test-nextjs-apps/
- https://blog.bitsrc.io/component-testing-with-cypress-12-and-nextjs-13-using-typescript-14825ea05f58
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