Refactor your Playwright configuration to run the Epic Notes app in tests. Enhance your end-to-end testing skills and ensure your app functions flawlessly.

Exercise 02 (Solution)

[00:00] From this moment onward, we're gonna be working with and testing the actual application, the Epic Notes app. If you take a look at the file tree in the Playground directory, you can already see all these different folders, all the source code for the app from the React components to Prisma schemas and so forth. We're not really interested in all of that as much as we're interested in how the introduction of a whole app affects our playwright setup. So let's open the playwright config dot yes and take a look at what changed here. So first of all, I've added a test dir option that points to test slash end to end.

[00:34] This is so playwright doesn't run other tests like unit tests or integration tests by mistake. So I'm keeping all my end to end tests in this directory. Then I have a global time out for all the tests which is fifteen seconds. I have a time out for individual expect statements which is five seconds. Then I've added the retries option to have two retries on c I and more importantly this use object over here that provides base URL which is the URL of the running app and this will be important a little later in this exercise as well as the trace option that we're gonna talk about in more detail in another section.

[01:09] Now the only thing that's missing is for Playwright to actually run the app, so whenever the tests run we are guaranteed that there is already an instance of the app ready to be interacted with. To do that I will head to the end of the config and add a new property called web server. This property allows you to describe what web server's playwright should spawn before the tests run. So here we're gonna have one test server with the following options. So the first option I need to provide is the command to spawn this server.

[01:38] In here you would normally use something like npm start, but this usually starts the production version of your app so it has to be built. And I don't wanna build my app as a part of the playwright setup because I wanna have a designated step for that on CI. Maybe I wanna cache the build artifacts and just have more control over them. So what I'm gonna do, I'm gonna make this command conditional. So I will say if we are on CI, then start an already built app.

[02:03] If we are not, let's run the development command npm run dev, the same command we used to develop the application. Now Playwright will run this command and then it will expect a web server to appear at either port or URL. I will use the port option because I already have the port variable over here declared, so 3,000 by default or from the port variable on the environment, and I will make sure to cust it to number so playwright understands it correctly. The next option I will specify is an important one, it's called reuse existing server, and I will set it to true. This option is telling Playwright that if there is already application running at this port, just reuse it, don't run this command again.

[02:44] This will be really handy when I am already developing an app and I have its dev instance running on my machine so when I run the tests they will be running against that existing app instance. Then a few quality of life improvements I will pipe s t d out and s t d error from this command that spawns the app and basically the app process itself to the same process that runs the tests. This way, I'll be able to observe any logs, warnings, or errors that my app runtime prints during the test run. This can help a lot during debugging failing tests. And now lastly, I will add the environment object over here and provide here the port which is the same variable that I am waiting the app on.

[03:25] This will make sure that the application starts at this port and also set the node environment variable to test just to differentiate the, you know, the test environment inside the app if I ever need to introduce some special setup. So now with these changes, Playwright is gonna run this command before the tests start, npm start on ci and npm run dev otherwise, it will wait for the app to appear at this port, reusing the already running and existing application, during development for example, piping errors and output of that respond process, and also providing this environment variables to the application itself. Now that the configuration is ready it's time to complete the end to end test that will run against my application. So I will head to tests over here and to end and I have a homepage. Test.

[04:13] Ts that I need to finish. So here I will declare a test case that displays the welcome heading. And I will continue with it here. First, I will grab the page object from destructor in the context and navigate using page. Go to to the home page which is just slash.

[04:31] And notice that I am not providing an absolute URL here anymore, that is because in the Playwright config here, the use option and its base URL option is set to the URL of the running app. And so any relative URLs I provide to go to will be automatically resolved against this base URL. That's really handy. So now that I'm on the home page, I want to find the heading that the epic notes displays and make sure that it's visible. A very simple test similar to the one we did for epic web.

[04:59] So I will do page dot get by role heading, the accessible name that says the epic stack. And I will create a assertion around it. So I'll expect this element to be visible. I believe that's about everything, I'm just gonna delete the rest of the instructions. So now that I have this test written it's time to run it.

[05:21] In my terminal I will run the same command npm run test end to end, but now playwright, you see the playwright is already spawning my application, I can see these logs, and then it starts the test run interacting with the page. Going to the home page, which I can see here in the loader, and then ascertain that the element is visible and confirming that the test case is passing. Now it's a good time to talk about the Playwright's architecture and how it makes your end to end test runs possible. Let's take a look at this schematic where I still have the architecture of Vitast. But you know what?

[05:52] It's not actually that different. Playwright also has the main process that does the test collection and runs them and reports the results to you. It has the workers that spawn your test files to make the runs more performant and provision proper isolation. Of course, both of these run-in Node. Js, so let's just annotate them as such.

[06:11] And there isn't really any need to configure the environment here, so you just run the tests. And the obvious change here from vTest is that in Playwright you now also have a whole browser process. So let's call it Browser. Over here. And so we have this browser process that runs our tests, only it doesn't.

[06:30] As I mentioned before, you still write and run your tests in Node. Js, but somehow they instruct the browser what to do, right? With things like page dot go to to trigger navigation. To make that possible, Playwright introduces a bridge between the Node. Js process and the browser process, and through that bridge it can communicate between the two, for example instructing the browser automation what to do.

[06:52] And that is an important distinction and the reason why in your Playwright tests you're running in Node. Js and cannot access things like DOM APIs, but you can use Node. Js APIs like reading from file system or spawning an HTTP server. That is a crucial distinction from something like VITA's browser mode where your tests run-in the browser and have full access to browser APIs, but they have an opposite limitation not being able to control anything Node. Js related.

[07:18] That is also the reason why whenever you want to instruct the browser to do something you usually use this bridge over here through some of the APIs that Playwright provides, for example the page object.

Running the app

[00:00] So you've got your first end to end test written and running, but it doesn't bring you much value just yet. Well, of course, unless you wanna make sure that Epic Web is running properly. But no, in real world, you wanna run your own application in your tests. And throughout this workshop, your application will be the Epic Notes app. It's written using the Epic Stack and it showcases all the functionality that you will find when testing your applications in the wild from authentication and sessions to creating, reading, updating, deleting operations, search, and many more.

[00:29] But before you dive into testing all of that, you have one more task to complete. Refactor the existing playwright configuration so it spawns your app before running the tests. To do so, you will use a designated property called web server. And once you have that done, head to the existing end to end test for the home page and complete it. And of course, run the test and make sure that it's passing.

[00:50] See you once you're done.

Do you know this feeling when you finally trust your tests? When running them no longer makes you brace for impact, but instead gives you the confidence to ship without second-guessing every deploy. End-to-end tests rarely earn that trust. They've earned a reputation for being expensive, slow, and unreliable, and most of the time, that reputation is deserved.

Today, I want to change that for you with Playwright.

In this workshop, my goal is to make you rethink what end-to-end testing can be. That means stepping beyond the cargo-culted patterns that gave E2E tests their bad reputation in the first place. That means getting so good at Playwright that you would feel confident writing tests that are meaningful and performant, and, dare I say, a pleasure to maintain.

Welcome to the Playwright workshop!

## What You'll Learn

End-to-end tests can get really complex really fast. I will teach you how to deal with that complexity by making intentional choices throughout the workshop: from configuring Playwright to arranging your test setup to reduce flakiness and get the test suite that you can trust.

On top of that, you will be crafting your own test experience through custom fixtures, disposable test data, and reproducible authentication snapshots. This will help you orchestrate tests for complex, real-world applications.

### Fundamentals

In the first block, you will get comfortable with Playwright. From installing it and covering the essential configuration options for a great testing experience both locally and on CI, to getting familiar with the test structure, the `page` object, and why it gives you element *locators* instead of direct DOM references. You will wrap up by writing your own custom fixture for type-safe page navigation in your end-to-end tests.

### Authentication

You will learn the difference between testing authentication as a feature and testing features that are *behind* authentication. Yes, those require entirely different approaches. Then, you will write tests for the most common authentication methods in web applications. With **basic auth**, you will create a disposable `createUser()` utility that creates a test user in the database and deletes it when the test is done. With **two-factor authentication**, you will create test OTP tokens and store their verification records in the database for your test user. And with **passkeys**, you will leverage a Chrome Developer Protocol session to create a web authentication client with the passkey you provide and use it in your test.

After that, you will explore how to create and manage authentication in your test setup using [Personas](https://github.com/kettanaito/playwright-persona), reproducible snapshots of different authentication states that bridge the DX gap of `setStorageState` in Playwright.

### Guides

Next, you will dive straight into practical tips for writing end-to-end tests: from provisioning mock databases and test data to mocking client-side requests. As a bonus, I will show you how to write tests by recording your interactions in the browser using Playwright's extension for Visual Studio Code.

### Debugging

And yes, I've saved the best for last. Debugging.

It's become somewhat of a tradition to include debugging techniques in my workshops, and this one will be no different. You will master the UI mode to preview and debug your tests *visually*, and after that, learn how to debug failed CI tests with the Trace Viewer. **This is, seriously, such a time-saver.** No more guessing why a test failed three commits ago on a machine you don't have access to. You will have the entire test run at your fingertips.

## Who Is This Workshop For

This workshop is for any developer who wants to write end-to-end tests they can actually rely on. For everyone who has watched a CI pipeline turn red because of a flaky test that passes locally. For everyone who has been told that end-to-end tests are inherently slow and unreliable, and refused to accept that as the answer.

You don't need prior Playwright experience to get the most out of these exercises, but a working familiarity with modern web applications and a healthy skepticism toward the current state of E2E testing will serve you well.

Master Playwright end-to-end testing: setup, authentication (basic, 2FA, passkeys), mocking, fixtures, and debugging with UI mode and Trace Viewer.

React End-to-End Testing with Playwright

Artem Zakharchenko

Writing tests for their own sake is a pointless chore:

```tsx
describe('add numbers', () => {
  it('should add two numbers', () => {
    expect(add(1, 2)).toBe(3)
  })

  it('should add two other numbers', () => {
    expect(add(3, 4)).toBe(7)
  })
});
```

Another annoying testing problem is when tests are too brittle, and paint your logs red even though the application seems to work just fine.

When your tests lack real purpose or seem to fail for no good reason, it's no wonder you start to question their value.

Tests are supposed to give you confidence in your code, and save you from shipping broken stuff to prod. So why does writing them feel like such a burden?

The problem is that tests like these are focused on implementation details instead of the underlying behavior. Everyone talks about the importance of testing, but there's a lack of understanding about how to write tests that are actually useful.

How would it feel to have 100% trust in your tests, knowing that any failures are not a false alarm? What if you could seamlessly translate the underlying behavior of your application into tests that are easy (and even fun) to write?

It's possible, but it requires you to take a step back from just syntax.

In order to have the confidence you're testing the right things in the right ways, you need to dig into the underlying patterns behind the scenes of a testing framework.

This is exactly what you will do in Testing Fundamentals.

In this workshop, Artem Zakharchenko, testing expert and creator of the Mock Service Worker API mocking library, will guide you through creating your own version of the Vitest testing framework.

Building a testing framework from scratch will give you a deep understanding of how the pieces fit together, and change the way you think about testing for the better.

## What You'll Learn

The workshop is broken out into four parts, each with its own challenges and exercises that build upon the last:

### Principles

First, you'll explore the principles and mental models that underlie testing strategies. This is where you will begin to distinguish between the intention of your code and its implementation details. When you focus the intention of what your code should accomplish, you can write tests that are more resilient to change.

### Test Structure

Next, you'll do a deep dive into the structure of the testing framework. You'll create your own `expect` and `test` functions, configure your test environment, and use hooks to manage side effects in your tests.

### Testing Asynchronous Code

Testing asynchronous code requires a slightly different approach when compared to testing synchronous code. Here you'll practice with testing promises and async functions, as well as handling errors and rejections.

### Moving to Vitest

Once you've learned the fundamentals of testing and built your own mini-framework, you will migrate your tests to the Vitest framework. This process will cement your understanding of not just the "hows", but also the "whys" of testing.

## Who This Workshop Is For

This workshop is for developers who have some testing experience, but feel like they're missing the bigger picture. If you're tired of writing tests that feel like a chore, and want to understand how to write tests that are actually useful, this workshop is for you.

Testing Fundamentals

Let’s face it, mocking can be really confusing.

First, you need to know what to mock. Then, find the right way to mock that thing so it doesn’t compromise your test suite. Over-mock, and your tests become pointless. Under-mock, and they get brittle instead.

In either case, you put in so much effort, and you don’t feel like you’re getting much in return.

This is where Artem comes in. He’s been proving developer misconceptions around mocking wrong for nearly a decade, and he’s here to make you a mocking pro.

## What You’ll Learn

In this hands-on workshop, you’ll learn:

- The purpose of mocking;
- What to mock and when;
- How to write mocks that bring value instead of being a maintenance chore;
- How to separate your mocks from implementation details;
- Type safety strategies for your mocks;
- And **all the mocking techniques** you will need to test your code!

By solving targeted, real-world problems using the Vitest framework, you’ll gain a comprehensive understanding of mocking and finally unlock it as a useful tool in your testing arsenal.

## Workshop Structure

This workshop contains 6 exercise blocks dedicated to various techniques on mocking different data types.

### Boundaries

Understand what mocking really is, and learn how it helps you create test boundaries. See what each mock you introduce does to your tested code using visual metaphors.

### Mocking Functions

Functions are at the heart of JavaScript logic. Learn how to mock functions for effective input-output testing. Create mock functions, spy on function calls, and mock function implementation to tap into the right behaviors of the tested code.

### Mocking Date and Time

Eliminate the side effects of ever-changing date and time in your tests. Learn how to freeze time and mock date/time-dependent code to ensure consistent test results across different runs and time zones.

### Mocking Globals

Explore how to mock implicit dependencies, in a non-intrusive way. Learn to mock global values, methods, and environment variables to create the perfect test setup without meddling with things you don't own.

### Mocking Network

Gain control over network communication and test your client-side code reliably. Intercept requests and mock responses using Mock Service Worker. Reproduce various network scenarios, from success and error responses to offline behavior and response timing.

### Mocking Modules

Understand when to use module mocking and explore alternative techniques before you do. Learn how to mock modules in a type-safe and efficient way using built-in APIs in Vitest.

## Who This Workshop Is For

This workshop is meant for all developers, both those who are new to automated testing and those who’ve been writing tests for years. If you are unsure when to introduce mocks into your test suite, or how to do that so you don’t have to refactor it the next day, this workshop was made specifically for you.

Mocking Techniques in Vitest

The closer your tests resemble how your software is being used, the more confidence they will give you. There’s so many great patterns stemming from this simple rule, patterns I’m sure you’re already using to write better tests.

Then, there’s the elephant in the room. **Your test environment.**

For decades, web developers have been testing their UIs in make-believe environments that are neither the browser nor Node.js. It made them come up with a frankly ridiculous amount of test setup, polyfills, and workarounds just to make it work. Remember when you had to mock `location` in tests? `window.matchMedia`? Yeah…

It’s time to abandon such practices. The tools have improved and there’s no excuse for you to be sleeping on it. It’s time for you to learn how to use Vitest Browser Mode for in-browser component testing!

## What You’ll Learn

In this workshop, you will learn a new approach to component testing that’s both different and the same. It is different because you will write and run your tests in the actual browser, taking advantage of the standard APIs and powerful browser automation. It is the same because it’s still the component level test you know and love, with rendering, querying, and asserting. 

Your users don’t interact with the UIs you build in JSDOM. They do that in the real browser, and now your tests will too!

### **Sunsetting JSDOM**

The first step in our journey is understanding why browser-like environments fall short. JSDOM has served us well, but it's time to recognize its limitations. You'll experience firsthand how browser-like environments like JSDOM are letting you down.

We'll explore examples of valid JavaScript code that works perfectly in browsers and Node.js but fails in JSDOM, undermining the value of the tests you work so hard to write. You'll discover why these inconsistencies happen and why moving to real browser testing is the solution.

### **Vitest Browser Mode**

Vitest Browser Mode allows you to run isolated component-level tests in the actual browser while providing the convenience and flexibility of integration-level testing. It's not a full end-to-end testing framework like Playwright or Cypress, but rather the perfect middle ground for component testing.

In this module, you'll learn:

- How to install and configure Vitest Browser Mode in your project;
- The technical differences between how JSDOM and Browser Mode run your tests;
- Steps needed to migrate existing JSDOM tests to Browser Mode;
- How to set up Playwright as the browser automation provider for your component tests;
- Common setup scenarios like applying global assets in tests and configuring Vitest for both unit and component-level testing within the same project.

### **Best Practices**

Choosing the right tools is important, but knowledge that transcends any particular tool is even more valuable. In this section, we'll focus on five key areas of best practices when it comes to testing your React components:

- **Queries**: Find elements on the page the same way your users or their assistive technology would;
- **User events**: Interact with the tested elements from the user’s perspective;
- **API mocking**: Use Mock Service Worker to intercept requests and handle their responses as well as discover how to efficiently use MSW in Vitest Browser Mode by creating a custom test context;
- **Element presence**: Test elements that should (or shouldn't) appear on the page reliably without false positives or flaky results.
- **Page navigation**: Learn where to draw the line when testing page transitions and routing in the actual browser.

### **Debugging Tests**

The true value of tests comes when they fail. But dealing with failing tests can be quite frustrating without the right techniques.

In this block, you'll learn some of my favorite debugging techniques that go well beyond console logging:

- How to inspect the DOM state at any point in test;
- Using the debugger statement to stop JavaScript execution entirely;
- Wielding conditional breakpoints to step through the problematic code.

These techniques will transform your approach to test failures from dread to confidence so the next time you see a failing test you will know what to do.

## Who Is This Workshop For

This workshop is for all React developers who want to write reliable and valuable tests for their components. Whether you're new to component testing or have been writing tests for years, you will inevitably learn new tools, APIs, and techniques to gain more value out of your test suite. That’s my sole motivation behind this material.

React Component Testing with Vitest

Do you know this feeling when a tool “clicks”? When you suddenly become so comfortable with it that it’s no longer just a means to an end but an instrument to craft better experiences for yourself. Over the past decade, that transition has happened with a bunch of tools for me.

Today, I want it to happen for you with Vitest.

In this workshop, my goal is to make you a Vitest superuser. And that means stepping beyond the basics and into the advanced. That means getting so good at Vitest that you would feel confident crafting custom test experiences, understanding the inner works of your test runner, and equipping that knowledge to solve everything from complexity issues to poor test performance.

Welcome to the Advanced Vitest Patterns workshop!

## What You’ll Learn

The overarching theme of this workshop is ***customization***. I believe your experience with tools is defined by how well you understand them and how comfortable you are when it comes to customizing them. With this workshop, I’ve collected some of the best techniques and pieces of advice to make you a true Vitest superuser.

I’m also taking this workshop as an opportunity to teach you the importance of the test setup. Throughout the exercises, you will be crafting your own test experience through things like custom fixtures, matchers, and equality testers. This will help you orchestrate tests for complex, real-world applications.

### Setup

In the first block, you will get more comfortable with Vitest. From writing and debugging tests faster with the Vitest’s extension for Visual Studio Code, to configuring and visually exploring code coverage and setting up multiple test projects to use your test runner to the fullest.

### Context

You will learn how to customize your test experience by creating *custom fixtures*. Discover the fixture syntax, its life-cycle, and how to implement them in a type-safe way. Then, note down the best practices of fixture design to make sure your custom fixtures eradicate complexity, not introduce it.

### Assertions

Following the topic of customization, find out how you can supercharge your assertions. First, you will create your own matchers to help express your expectations toward your tested app and make your tests read like human language. Then, explore what is an equality tester and how you can teach the Vitest’s built-in `.toEqual` matcher to compare the incomparable.

Nail down how to write assertions for eventual states with `expect.poll` and become in full control of how much information you get out of failed assertions by understanding the balance between the hard and soft assertions.

### Performance

And yes, I’ve saved the best for last. Performance.

Learn how to profile slow test runs using built-in metrics in Vitest as well as the `vitest-profiler-plugin`. You will read the CPU and heap profiles, understand what they mean, and how you can use them to hunt down the problematic areas of your tests.

Everything past this point is techniques to make your tests faster. **We are talking up to x40 times faster** (that’s not a typo). Take a peek behind the scenes to see how Vitest orchestrates test runs and what defaults it has in place to ensure reliable results. Go through the difference between parallelization and concurrency in tests, explore the effects test isolation has on performance, and learn how to split your tests into shards for faster CI/CD jobs.

## Who Is This Workshop For

This workshop is for all developers who want to learn how to customize Vitest to create better, custom test experiences on top of it. For everyone who has felt like adding a new test in your project feels like fighting against the entire world. For everyone who has found themselves lost before a slow test suite.

As the name suggests, you will be going through advanced topics, which makes a prior basic experience with Vitest mandatory to get the most out of these exercises.

Advanced Vitest Patterns 

The Testing Bundle

Master Playwright for efficient end-to-end testing, covering setup, authentication, and debugging to enhance your web app's reliability.

React End-to-End Testing with Playwright Introduction

Workshop Introduction

Master end-to-end testing for web applications and ensure quality from UI to backend, using effective strategies to simulate real user scenarios.

Fundamentals Intro

Master end-to-end testing with Playwright by installing dependencies, configuring settings, and writing your first test to enhance your web development skills.

Exercise 01 (Solution)

Install & configure

Enhance your Playwright tests with type-safe routing. Implement a custom fixture to avoid navigation errors and streamline your end-to-end testing process.

Exercise 03 (Solution)

Custom fixtures

Master Playwright by installing, configuring, and implementing custom fixtures, then prepare for essential authentication testing in your app.

Fundamentals Outro

Fundamentals

Master end-to-end testing by effectively handling authentication as both a feature and a dependency, ensuring robust app functionality and user experience.

Authentication Intro

Master username and password authentication by creating a test user and implementing successful and failed login test cases to ensure robust functionality.

Basic

Master two-factor authentication testing by implementing OTP code verification. Enhance security in your app while building effective test cases with ease.

Two-factor authentication

Master passwordless authentication by writing end-to-end tests for passkey login flows using Playwright and enhance your web development skills today.

Passkeys

Master testing user behaviors behind authentication by managing notes in your app. Enhance your skills with practical, hands-on exercises.

Exercise 04 (Solution)

Protected logic

Master efficient authentication testing and enhance your end-to-end tests. Unlock the secrets to robust application security with Item 99.

Authentication Outro

Authentication

Master end-to-end testing by enhancing your setup with best practices, efficient test data management, and user-centric approaches for reliable results.

Guides Introduction

Enhance your testing strategy by isolating your test database. Set up a dedicated test environment with Playwright for reliable end-to-end testing.

Mock database

Master note management by testing user authentication and data handling. Prepare and clean test data to ensure seamless functionality in your application.

Test data

Master end-to-end testing by using Playwright to automate changing a user's name in an app. Enhance your skills and streamline your testing workflow!

Recording tests

Master API mocking with Playwright to ensure reliable end-to-end tests by intercepting third-party requests and creating stable test environments.

API mocking

Master debugging techniques in end-to-end testing and enhance your development skills. Dive into practical exercises and elevate your problem-solving abilities!

Guides Outro

Guides

Master debugging end-to-end tests with Playwright. Gain insights into test failures and enhance your app's reliability through effective strategies.

Debugging Introduction

Debug and fix a failing test case in Playwright by using UI mode to visually trace actions and ensure user nodes appear correctly.

UI mode

Master debugging with Playwright's Trace Viewer to analyze a failed test run, identify issues, and enhance your testing efficiency. Fix it now!

Trace viewer

Master essential debugging in Playwright with UI mode, Trace Viewer, and more. Enhance your testing skills and troubleshoot like a pro!

Debugging Outro

Debugging

Master Playwright for comprehensive web app testing and enhance your skills with effective end-to-end user journey tests. Stay safe and test smart!

React End-to-End Testing with Playwright

React End-to-End Testing with Playwright

Transcript

Running the app

Transcript