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

Exercise 01 (Solution)

[00:00] A good place to start is to understand how Prisma knows which database to use. That behavior is configured in the file called dot environment that lists all of these environment variables. The relevant one here is the database URL one. You can see that it points to a local file at data dot DB. So this is the database that Prisma uses alongside SQL to perform database operations.

[00:23] So if I want to deviate from this behavior and make it right to a different file, I will create another environment file called dot environment dot test and this file will contain all the differences, all the environment variables that apply only in tests. I will copy this variable and I will change the file used for testing to test dot db. I will keep the connection limit parameter set to one because SQLite locks the entire database during write operations and I don't wanna introduce a race condition where one test will be writing something to the database, lock it, and then another test will run-in parallel also attempt it to write something. That'll be terrible. So I'm keeping the connection limit set to one.

[01:02] On its own, having this environment. Test file does nothing, I need to load it during the test run. So I will go to the playwright dot config. Ts and here you can see that we're using the dot environment package to load the environment files. So by default it will load this dot environment file.

[01:19] Let's opt out of that behavior and import from dot environment an object called dot environment I will call dot environment dot config this will reproduce the previous behavior and load in the dot environment file, the default one, and then I will call the same method again but not provide a different path because I want to load the dot environment dot test file. To make sure that my variables in the dot environment. Test actually override the same variables set in the root environment file, I will provide an option here called override and set it to true. So now when Playwright executes this configuration file, it will pull variables from both of those environment files. And the only thing I have to do now is to also propagate this database URL variable to the application that Playwright spawns.

[02:08] So down here, in the web server object, I will go to the environment object and add the database URL and load it from the current process. Database URL. So what I've done here is actually two things. I'm loading my environment dot test file in the Node. Js process that is the Playwright itself, the same process that runs the configuration and the tests.

[02:30] And then secondly, I'm also propagating the same database URL change to my application. So so whenever backend logic fires against Prisma to create certain resources or read certain resources, it would know that it has to do so against my test database. If I try running my tests now, they will fail because the test database is not prepared. To prepare it, I will create a global setup file for playwrights in a file called playwrights dot setup dot ts. You can choose whatever name you want.

[02:59] So in that file, here I will export a default function called global setup and in this function, I will prepare my test database for the test run. It will consist of two steps. First, I will generate the Prisma client. I will import from node trial process function called spawn synchronously. I will use it to spawn a Prisma process and call the generate with the SQL flag because we're using SQLite in the application.

[03:27] And I'll also provide the standard input output option to inherit so I'm able to see all the logs, warnings, and errors that Prisma prints while generating the client. The second step, I want to apply those initial migrations. In a similar fashion, I will call spawn synchronously. I will run Prisma migrate reset then dash dash force and skip seed. So what I'm doing here is I'm forcefully resetting my database to the initial migration defined in the SQL file and then skipping seeding any initial data because I don't need them for my tests.

[04:03] And in the same manner, let's set s t d I o to inherit. Since this is a global setup, both of these commands will run before my tests, thus preparing the database and making sure that it's in the right state for the test run. But if I go to the package. Json file and check how Prisma is prepared in the production run, I can see that first we're running migrate deploy and then we generate in the Prisma client. I will align my test setup to have the exact same order so there are less discrepancies between the production run and the test run.

[04:33] Now the only thing remaining is to plug this setup file into Playwright. I will head back to Playwright config and add a new option called global setup and point it to the setup file at playwrights.setup.ts. Now let's take a look at the end to end test that we have. Here we have the create notes test from before that uses the authenticate fixture to assume a user persona. In other words, I expect that this user will be created in the test database, alongside the notes because we are trying to create the note as well.

[05:04] So let's run these tests and see which database actually gets used. We can see the test succeeding and also that our Prisma preparation steps fire as a part of playwright's run. This is the part of the global setup. And if I go to my project in the Prisma directory, I can now locate this test. Db, this is our test database.

[05:29] If I open it, I can observe the resources created. For example, if I go to the user table, this is my user that was created during the authentication in the end to end test. If you take a look at the global setup, we are resetting the database at the first step before the tests run. This means that after a test run, you still have the intact state of the DB if you want to investigate it. So for example, if some of your tests failed, you are able to open this database at the exact state and look around and figure out what's wrong, even if you run this test yesterday.

[06:00] So as long as you didn't have any other test runs, the TestDB will always be the latest snapshot of the database, which I find really handy. Naturally, the way you arrange the database in your end to end tests will differ depending on the database that you're using. In our case, we're using Prisma with SQLite which is really handy because SQLite writes the database file to disk so we can point to a different file to use for testing purposes. Now, what you have in your application might be different. But no matter the setup, you still need to make sure to procure proper isolation on the database level.

[06:31] So if you are using something like in memory databases, you can prepare a special instance and point your application to use that instance in tests. For dockerized databases like Postgres, you can rely on tools like test containers to spin the test instance of the database and point your application to use that container. Just remember that the goal here is to ensure reliable test runs through database isolation. It will give you both control over the data created during the test run and make sure that no unwanted resources can affect the test results.

Mock database

[00:00] Up to this point whenever we created resources in the database we were actually writing in the same DB used during development. While it may sound practical, I highly encourage you to separate your test database and any other database instances you might have. The reason for that is simple, isolation. You are well familiar with the isolation on the test case level, but it doesn't stop there. Isolating your test database is equally as important.

[00:26] By doing so, you will limit the number of things that are allowed to influence your test run, and also improve other aspects of testing such as the ability to debug failed tests. So if those happen, you'll be able to open the test db and observe its state. In this exercise, your task is to improve the test setup to use the designated test database. To do that, you will create a setup file where you will prepare the test database, then connect it to Playwrights and run the existing end to end test, making sure that all the resources they create are created in the designated test database.

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.

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

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

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

Mock database

Transcript