Learn Cypress, Jest and Scss

It's tempting to pick up a framework which has preselected flexbox or grid as the layout tool of choice, but it's important to learn when and why to use each method. This leads to slimmer stylesheets which results in better site performance, and less likelihood for "hacks" to make one method do what the other does inherently better. 

Throughout this collection, we will be progressively styling a responsive landing page template while building your knowledge on when to select grid or flexbox for any layout scenario. Spoiler alert: sometimes the best solution is using both!

The specification describes a CSS box model optimized for user interface design. In the flex layout model, the children of a flex container can be laid out in any direction, and can “flex” their sizes, either growing to fill unused space or shrinking to avoid overflowing the parent.

flexbox

Create a Landing Page with CSS Grid and Flexbox

One of the most important — but most ignored — practices for web developers is performing end-to-end testing on applications before they go live into production. You know: making sure they work like they’re supposed to. But testing can be tedious, and definitely not fun.

In this course, Brett Cassette will show you how you can test all layers of your application stack, simultaneously, with Cypress. When you use Cypress, it’s like having a robot that uses your app the way a real user would. Cypress reports if things work the way you designed them to — and if they don’t — every step of the way. And it’s fun.

After completing this course, you’ll be ready to apply the same E2E testing principles to your own applications. Stop leaning on your QA department (if it exists) to stress-test your application, and ship your app knowing it’s ready. 


Fast, easy and reliable testing for anything that runs in a browser.

cypress

Test Production Ready Apps with Cypress

Imagine the following.

You join a new project and after getting access to the repo you notice that there's no tests.

You decide to ask the team whether they are in different repo or something and unfortunately the answer is:

>We don't have any tests, we didn't have the time.

😐

In this collection we're going to learn how to add e2e tests with cypress.io to an existing React app in order to do two things:

- 🌟 Ensure that our app currently works as intended
- 🌟 Allow us to add features to it with a technique called "Cypress Driven Development" 

In less than 20 minutes we're going to go through:

- ⚡️Adding cypress.io setup to an existing project
- ⚡️Testing search functionality with `data-cy` properties
- ⚡️Using "Cypress Driven Development" to add a new feature to an app
- ⚡️Use Cypress UI to debug an API response
- ⚡️How to use `cy.only` and `cy.skip` in order for us to build our e2e test suite faster

and much more!

Add e2e tests with cypress to a React application

The tools available for unit testing have come a long way. While testing may never be “easy”, the available tools have certainly moved testing closer to the simple end of the spectrum. Full end to end testing hasn’t quite kept the same pace and as a result many applications are testing manually and often by users in production. Cypress provides a testing environment that makes end-to-end testing fast and reliable with a simple API that makes creating automated unit tests for your web applications a no-brainer.


End to End testing with Cypress

In this collection, we build a minimal flashcard application using React, primarily focusing on function components and the hooks API. To make sure we can understand and maintain existing code, there are also a few lessons toward the end that use class components so you can get familiar with the syntax. We cover important React concepts, and sprinkle in libraries that are pretty standard in the ecosystem like @reach/router, Jest, and React testing library. We start with create-react-app so we can get right into it without worrying about configuring tooling. There's [a separate course for that here](https://egghead.io/courses/modern-javascript-tooling-with-react?af=5mx0ie)

jest

Build a React App with the Hooks API

In this course we are going to work through properly setting up Enzyme with Jest to test rendered components. This includes the nitty gritty of making our testing environment work with various versions of React. After we get our environment setup ready, we’ll work through the different ways we can render a component within our test pages. With a rendered component we can now test component methods and properties to assert that they are what is intended. 

React is one of the web’s most popular frameworks for building JavaScript applications. 

If you know what you’re doing, React can drastically simplify how you build, use, and maintain code.

Whether you’re a React newbie or you’re ready for advanced techniques, you can level-up with egghead. Explore our in-depth courses, lessons, and community resources to build more powerful applications and crack open your career.

react

Test React Components with Enzyme and Jest

CSS uses a global namespace for CSS Selectors that can easily result in style conflicts throughout your application when building an application using modern web components. You can avoid this problem by nesting CSS selectors or use a styling convention like BEM but this becomes complicated quickly and won’t scale.

CSS-in-JS avoids these problems entirely by generating unique class names when styles are converted to CSS. This allows you to think about styles on a component level with out worrying about styles defined elsewhere.

In this course, you will learn how to express popular SCSS (Sass) language features using latest JavaScript features. We will convert simple examples from SCSS to CSS-in-JS. As a designer or (S)CSS developer, you should be able to follow without extensive JavaScript knowledge, understanding SCSS is required though. We will not be using any particular CSSinJS libraries. Instead, we will focus on a base knowledge you need later if you use any CSSinJS library.

Sass is the most mature, stable, and powerful professional grade CSS extension language in the world.

scss

Convert SCSS (Sass) to CSS-in-JS

Your app can react in various way on different network conditions. Cypress has a great toolset for setting up those conditions, which enable you to test your app thoroughly. That way you can ship your app with confidence.

Cypress’ .intercept() command is one of the most fun command to use. And it’s also one of the most useful.

Especially when you are done with all your happy paths and want to increase your test coverage with some edge cases.

These edge cases can mean different data, headers or server behavior. You can modify all of these, dynamically or with a static fixture prepared beforehand

Test Network Edge Cases with cy.intercept() Command in Cypress

Have you ever wished for access to conditionals or iteration when writing styles? How cool would it be to use functions to write styles? SCSS has that and more! SCSS is a superset of CSS. Any valid CSS is SCSS, they even have the same syntax. SCSS borrows features from other languages to write smarter, reusable and more readable styles. This course will focus on how to use SCSS’s more useful features, compare them against each other and assess when their usage is appropriate.

Learn the Best and Most Useful SCSS

Best practices for building & testing redux applications have changed dramatically over time. This course aims to be a comprehensive and up-to-date resource for those seeking to confidently test their redux apps. Whether you're just getting started or want to improve on your existing testing strategy, there will be something in this course for you.

This first few lessons of this course look at how to add jest to an existing react/redux application that was built on top of [vite](https://vitejs.dev/). We cover basic functionality like using `npm test` vs `npx jest` and generating and using [code coverage](https://jestjs.io/docs/cli#--coverageboolean) to inform our testing strategy.

The next 10 or so lessons cover the specifics of unit testing the redux code in our application. We'll go over how to test reducers, selectors and thunks. As part of this we'll touch on mocking APIs and using [Redux Mock Store](https://github.com/reduxjs/redux-mock-store) as well as running actions through our applications' actual reducers to broaden our test coverage.

In the final part of this course we'll look at how we can test our redux connected react components using the various utilities that come with the [React Testing Library](https://testing-library.com/docs/react-testing-library/intro/). We'll cover simulating various kinds of user input with the [User Event Module](https://testing-library.com/docs/ecosystem-user-event), populating our redux store with test data, using [jest spies](https://jestjs.io/docs/jest-object#jestspyonobject-methodname), how to wait for asynchronous tasks to complete, and several approaches for finding & asserting that visual elements exist on the page.

This course is built on top of content that was created for the [Modern Redux with RTK and TypeScript](https://app.egghead.io/playlists/modern-redux-with-redux-toolkit-rtk-and-typescript-64f243c8) course and I highly recommend you start there if you haven't completed it already. It does expect a *basic* familiarity with react, redux and jest. TypeScript is used in these lessons, but is not a major focus and hopefully won't distract you too much if you prefer plain JavaScript.

No matter your experience level with redux and testing react applications, I'm confident your abilities will level up as you watch this course and follow along with the examples.

Thank you!

Confidently Testing Redux Applications with Jest & TypeScript

Web accessibility (also referred to as a11y) is the design and creation of websites that can be used by everyone. Accessibility support is necessary to allow assistive technology to interpret web pages.

React fully supports building accessible websites, often by using standard HTML techniques.

Erin Doyle is an expert in creating accessible React applications and has developed a course that will give you a concrete process for auditing react apps for accessibility. In this course, you will go through different tools and libraries to audit components in a React app.

Auditing React Apps for Accessibility 

Techniques to improve your CSS, Sass, and HTML implementations for everyday scenarios. 

Learn the Fundamentals of CSS and Sass to Create Modern and Responsive Layouts 

Copy/pasting the same code is redundant and updating copy/pasted code slows development velocity. Mixins are reusable chunks of code that are included, similar to calling a function, instead of copy/pasted.

Mixins have some nice features:
- Arguments just like functions.
- Arguments can have default values and optional values.
- Named arguments allow us to use optional and default arguments when the mixin is included.
- Variable arguments allow us to have a dynamic number of arguments when the mixin is included.
- The @content directive allow us to add additional styles when the mixin is included.

In this lesson we learn how to DRY up the code with the SCSS @mixin directive and make copy/paste a thing of the past.

Reuse Styles with the SCSS @mixin Directive

Updating the same color or metric multiple times is no fun. SCSS variables improve maintainability by allowing one name to represent a value that can be used anywhere. SCSS variables also give us the power of creating our own naming conventions to express the intent of specific values. In this lesson we learn how to use SCSS variables to assign user friendly names to colors/metrics so one value change will update that value in all the right places.

Use SCSS Variables for Readable and Maintainable Stylesheets

SCSS nesting can produce DRYer code by targeting child elements without having to write the parent class. Nesting up to 3 levels deep can help us understand relationships between styles. The SCSS parent selector represents the parent class, so it can DRY up targeting pseudo-elements/classes and be an asset for naming conventions. In this lesson we learn how to remove the redundancy of targeting pseudo-elements/classes, and child elements by taking advantage of SCSS’s nesting and parent selectors.

Organize Styles with SCSS Nesting and the Parent Selector

In this lesson we learn how to set up SCSS  and transpile your SCSS code into CSS with node-sass.

Transpile SCSS to CSS using node-sass

Tired of dealing with monolithic CSS files? Are requests for multiple CSS files hurting your performance? In this lesson we learn how to separate our styles with SCSS partials, and how SCSS imports compile to one file so there's only one request.

Organize SCSS into Multiple Files with Partials

We can write reusable styles with the SCSS @extend or @mixin directives. Which one is better? It depends. A better question is, how do they differ?
Extends:
change the source order, mixins don’t.
maintain relationships, mixins don’t.
share inherited traits, mixins don’t.
can extend multiple classes, mixins don’t.
can create multiple class declarations in the compiled CSS, mixins don’t.
can use the placeholder selector, mixins don’t.

Mixins:
can accept arguments, extends don’t.
can pass additional content, extends don’t.
repeat code when compiled, extends group class names together.
work well wIth media queries, extends have a limited interaction wIth media queries.

In this lesson we learn about writing reusable styles with the @extend directive and how it compares to the @mixin directive.


Reuse Styles with the SCSS @extend Directive

Writing similar classes with minor variations, like utility classes, can be a pain to write and update. Sometimes just a single character is the only difference between classes and updating the defining parameter means we need to change it for every class name and value. We can write a class one time and the @for directive can write all the minor variations for us. If the similar classes need to be updated, with the help of the @for directive, they only need to be updated once. In this lesson we learn how to leverage the power of the SCSS @for control directive to relieve the pain.

Write similar classes with the SCSS @for Control Directive

The SCSS @for directive is great when we know how many iterations are required and we only need 1 variable. What if we need multiple variables to iterate over data sets? Hello SCSS maps and the @each control directive! In this lesson, we’ll check out iterating with lists and looping over data sets with maps and the @each directive.

Loop Over Data with the SCSS @each Control Directive

Writing SCSS @functions is similar to writing functions in other programming languages; they can accept arguments and have return statements. SCSS provides a ton of great features, but sometimes we need to roll our own function. We can do that too! They’re useful when the desired functionality isn’t available from the built in SCSS functions and a mixin just won’t do. In this lesson, we learn how and when to use SCSS function directives.


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