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)

[00:00] Fixtures are the first class citizens for extending functionality in Playwright, and the reason why we're talking about them so early into the workshop is because I want you to get comfortable with creating your own fixtures and extending the test experience. For example, by making page navigation in your tests type safe. As I mentioned previously, I'm going to achieve that by replacing the default page go to functionality with my custom fixture called navigate. And I already have the module prepared where I'm going to implement all my custom fixtures called testextend. Ts.

[00:31] The naming here doesn't really matter, you can use whatever module you want. Effectively this is part of your test setup. I will start the implementation for my Navigate fixture from the types. I will declare an interface called Fixtures where I will list all my custom fixtures. So I want to create a fixture called Navigate, I will list it here as the key, and the value here will be the type of that fixture, what I'm gonna be calling in tests.

[00:54] So here I will use the types generated by React Router to help me out. I will import two things, first the href function which is a URL builder, and then the type called register. This is a generated type that if you inspect it has this pages property that contains all the generated routes that I have in my application. And I am gonna use them to infer what kind of routes are supported in my tests. So heading back to my test extend, here I'm going to declare a type argument called t that extends key of register and its pages property.

[01:29] Basically taking all the keys of the pages object which is all these route strings, and storing them in a type called t. Here in the arguments, I will extend this basically, spread this arguments array and provide the type the parameters type of href to make sure that the call signature of my navigate fixture is the same as the call signature of the href function which accepts the path and an optional argument for building my routes. In this case for testing. And I will provide the t as the type argument for the h refs so we are inferring the exact routes that we're using and have the collocation between the route path and the route parameters. The only thing left is to say that it returns a promise that resolves to void.

[02:15] Now this is just a type story of this fixture. To actually implement the runtime behavior, I will import from playwright slash test the test function under an alias test base. And here I will declare my own test function that equals test base dot extent with the fixtures that I just created. And I will export it because I will use this one in tests. So here, typescript already errors here saying that we're missing some fixtures.

[02:42] So let's implement the navigate fixture. I'll keep the types over here. So I'll provide the navigate key, which will be the implementation for my navigate fixture. We'll turn it into a synchronous function that accepts the test context, the same context that we have in test cases. And the second argument will be the use function to actually provide the value for this fixture.

[03:02] I will call it immediately and await it. And here, if you inspect this types, you will see that this is already the types inferred from my fixtures interface above. This is this type signature. So I will have the arguments here, and I will use the regular page go to to still provision the navigation. I don't wanna implement that myself.

[03:22] So I'll head to this first argument, the context, and grab the page and await page dot go to. Make this asynchronous so we can await it. And here I will call the href function from React Router and provide it with the args. And this way I will have the type safe URL builder building this end destination route and providing it to page go to to actually trigger the navigation. And this completes the implementation of the fixture, so I have the call signature in typescript and I have the runtime behavior in Playwright.

[03:54] Playwright implements this particular way of building fixtures to expose you to the test environment by this test context where you can grab things like page or context or anything else really that Playwright gives you and have a lot of capabilities when it comes to building your fixtures. You also have this closure here, which is smarter than it looks, because everything before the use function is your before hook and everything after is your after hook. So you can provision some resources before you expose the fixture and then use this after part to clean up those resources and have nice and performant tests. So now that I have this fixture, the only remaining part here is to use it in my test. I will head to homepage.test.ts.

[04:34] And for now, in order to have this fixture over here on the test context, I will replace this test function. Instead of playwright, I will import it from my tests test extent. And now that I have this test, if I head to the test this context object, I will see that the navigate fixture is here, and that's exactly the function that I have implemented. Before I change anything from now, I wanna take a look at this expect function that it errors because I'm not exporting the expect function anymore. I will jump quickly to my test dot extend, import the expect from typescript, and just export it as is.

[05:10] So I am able to use it in tests from the same module without having to switch here and back. So now I will replace the go to function with the navigate fixture. So for the home page, no visual changes appeared. But if I try to provide the argument the path, you can see that now I have this whole list of all the routes existing in my app. And if I make a mistake, TypeScript will let me know immediately your route is not assignable to the keys of pages that you have.

[05:37] What's even cooler is that when I want to go to a path that has a path parameter, like here, the provider, the navigate fixture will error because I am forgetting the provider argument. So I will provide the second argument here, the object and the provider string with the exact value so I'm able to build the correct route and then navigate to it under test. So let's clean this up and go to the homepage. Slash. And now that this is ready, I'm gonna run this test to make sure that Playwright is using my fixture correctly and runs the rest of the test as is.

[06:10] Awesome. So I can see that a test is passing. And from the logs of my app, I can also see that we are navigating to the home page because that's exactly what navigate here does in the test. So let's take a look at what's happening here. Because we're replacing or extending the test function, we now are able to imbue this default test context with our custom fixtures such as the navigate fixture, and we implement them by describing their types in this fixture's interface and then extending the default test function by calling dot extend and implementing our fixture.

[06:40] So in this case, we're using the default page object and its go to method to go to the built URL by React router which remains type safe due to the generated types. Type safe routing is becoming an essential part of any JavaScript framework and is already supported in React router, 10 stack start and Next. Js just to name a few. And I highly encourage you to benefit from those generated types not only while building your apps but also while testing them.

Custom fixtures

[00:00] One thing you will do in every end to end test that you write, and do quite often, is navigating between the pages in your app. And you already know that to do so you call the go to method on the page object. And you provide it the URL where you want to go, where relative paths will be resolved against the URL of your app. And because you're gonna be doing this pretty often, it would be nice to know when you're making a mistake in this path and going to a route that doesn't exist. And most importantly, know that before you waste your time running the test, waiting for it to complete, and then tell you that you made a mistake.

[00:31] No, there is a much better way to do so and that is introduce this safety on the type level. In much simpler terms, I'm talking about type safe routing in your end to end tests. But rightfully so, the default go to function doesn't know about what kind of routes your application has. Playwright cannot assume the routing library you are using and what kind of types it generates, if any. This is where you have to teach it.

[00:55] And that is precisely your task for this exercise. Follow the instructions to implement your own custom fixture called Navigate to support type safe routing in playwright tests. Once you do so, refactor the existing tests where you use this new fixture and enjoy the type safety end to end.

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

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)

Running the app

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

Custom fixtures

Transcript