Master Remix stubs for isolated component testing, handle edge cases, simulate user states without full end-to-end testing.

Use CreateRemixStub for Remix components with mock data. Test integration with React Testing Library for proper rendering and DOM element waiting.

Rendering Components with Mock Data

[00:00] Right from the get-go, we're getting an error. Uncaught error, used loader data must be used within a data router. So if we go into here and take a look at the component that we're rendering, right there, that's the used loader data that needs to be rendered within a data router. So to be able to do that,

[00:17] we need to bring in CreateRemixStab, which is going to be able to create a fake version of the Remix app for us. So we create the stab right here. We're going to say our app, so CreateRemixStab returns a component that we're just going to call app.

[00:34] This is CreateRemixStab and we define routes. These routes are actually going to resemble React router route configuration. So if you've ever worked on React router before, this should actually be pretty familiar to you. So we're going to say our path is the same path as what it actually is. So it's going to be slash users slash colon username.

[00:53] So we've got that param. Then our component will be the username route. The thing that we want to render itself. Then we'll have a loader and that is going to, we want this to be the same type of thing, like we're going to return mock data and stuff,

[01:11] but we want it to be the same loader as the loader of our component or the route that we're rendering. So we're going to use the same return type. So I'm going to say return type, type of loader, and this should be the awaited version of that.

[01:30] So that is what is going to return. So let's return JSON. This utility is going to come from Remix. So let's import JSON from Remix run node. There we go. Then JSON is going to return

[01:49] a user and user join display, and that can be whatever we want. Now, I am clearly added an extra thing there. Then we've got our loader that needs to be from here. We're just going to bring in the type though, because that's all we need. It's not the real loader, just the type. Okay, great.

[02:08] Yeah, so we've got our user right here. We have our join display here. Probably better to just say user.created at to locale date stream. There we go. That makes it more realistic. Then once we've got all of that,

[02:27] we can render the app instead of our username route. So we'll say app, and we've got it around this wrapper because we still need the authenticity token that's being rendered by our route. Then we can save that and see what our tests say now. Okay, we've got another error this time,

[02:45] and the error is no routes match location slash. So we set our path to be slash user slash username. We could remove this, but we actually need that param. That's our application actually relies on that. And so what we're going to say instead is our app is going to have some initial entries. And so the initial entry,

[03:04] that's an array of entries in like the history stack. We only need like one. We could have multiple, but we only need one. And that is, we're just going to land on this page. So users, and then we want the path, the username to be our user's username.

[03:20] So we'll make this a template string and say user.username. And that will be our initial entry. We could also say initial index, initial, oh, whoops, right here, initial index and say initial index is zero, but that's the default. So we're all set there. Okay, and with that, our test passes.

[03:40] We can take a look at screen.log playground URL if you want to, and then pull that up right here, our markup, oh dear, is very minimal. So there's a problem with that. Oh, I know what's going on. The problem is that it actually is going to take a second

[04:01] for this to actually render our UI. And so that's why we're using these find by queries down here because we need to wait for those to show up. And that's what Olivia the owl was trying to explain and I just ignored it. So there you go. So if I do it after the heading,

[04:17] then we get the full UI and let me move that over here. So this is what our UI looks like. Yeah, it's missing some styles and stuff, but that's the general idea. And we can use that to select the heading and the image and the link and all of that stuff. And then of course you can always say screen.debug right there.

[04:38] And there it's all laid out and nicely highlighted and everything, which is pretty cool. Okay, great. So let's just do a quick review. We brought in the CreateRemixStub, also brought in the type of the loader and JSON for this test.

[04:55] We created a RemixStub that gave us back an app. We defined the routes that we want for this test, specified our component and our path and our loader. And then instead of rendering our components, we're rendering the app. And we're still using React Testing Library to render that. The RemixStub is just creating the app

[05:14] that has all the context necessary for our components to be rendered. Then we also specify where we want to be rendered because we can have multiple routes. And so we need to say which route we want to have active and what params they will have and everything. You could also do search params as a part of this as well, if you wanted to.

[05:32] And yeah, then we wait for these things to appear. It doesn't take long, but it does take a moment. So we use screen.findby for these queries. And in general, at this level of testing with integration testing, which is what we're doing here, we want to typically use the find variant

[05:52] of these queries anyway, because if you're using the get variant of the query, so if we say get by role and all of those, then those are not async. So they will look for those things in the DOM right now. And unfortunately, you can't really rely on that ever. Somebody could add some asynchrony to things

[06:11] and that could very well be a perfectly fine thing. And so when you're at this level of testing, I actually recommend you typically want to use the async version of all of the queries. The exception to this being like, if you want to verify that something doesn't exist, then you're gonna use query by,

[06:29] and you just want to, the tricky thing with an async thing is how do you know that it never shows up? But yeah, so you're typically gonna be using find by, sometimes you'll use query by. And then if you're at a lower level test, then using get by variant to the queries is just fine.

[06:47] And interestingly, when you're in Playwright and you're doing all of the locators and things there that are testing library inspired, those are also going to be async as well. So once you get to this level of testing on the testing trophy, we're in the integration piece right now. Once you get to this level, you're pretty much better off doing the async queries.

[07:06] Okay, I think that is enough for this step. So let's keep on going to the next.

Creating a Stub for Testing Component Logic in Remix

[00:00] So here we've got our username route, and if we are not logged in, then it's just going to say when the user joined, it'll say their name, it'll have their avatar, and it will have a link to their notes. But if we log in as this user, and then go to there, then we're also going to get a logout button and an edit profile button.

[00:19] So there, right there, we've got some logic. And having some logic for this, sometimes it makes sense to do at a lower level than an end-to-end test, especially when you get into a much more complicated page. It's nice to be able to isolate your test down to the specifics,

[00:36] so you can handle edge cases and various other states that the user can be in for a particular component. So in this first step, we're going to create a remix stub, so that we can stub out all of the stuff that Remix does for us, because this is rendering a form, an action form.

[00:55] This is rendering a link. And there are various other things that Remix sets up in context for us, like our loader data, for example, for even loading this stuff. So we need to have a stub, which is basically just like a fake version of a real thing. It's kind of like a mock, but this doesn't keep track of how it's called or anything.

[01:13] It's just like a fake object. It's like a setup function. So we're making a stub of our app, and then we can render it to render this out and make some assertions on the stuff that's being rendered. So that's what you're going to be doing in this exercise. I hope you have a great time!

We all know the drill. The code works on your machine but you didn’t realize the impact of the change you made and it breaks in production. This problem grows exponentially as your application’s size and usefulness grows. Unpredictability can be a developer's worst nightmare.

However, many developers find it difficult to effectively test their code. Manual testing gets tedious fast. Complex logic and async code can be tricky to test effectively.

The Full Stack Testing Workshop will equip you with the tools you need to ensure your app works now and in the future. You'll learn how to write modular, maintainable tests that cover all of your code, from the backend to the frontend.

As the author of the de-facto standard testing library for web development (called eh… Testing Library), I have some solid opinions that have led many teams to much more confidence shipping their code. Let’s get you some of that confidence.

## End-to-End Testing with Playwright

With end-to-end (E2E) testing, you can validate a web app from the user's perspective. This is the closest you can get to a real user interacting with your app. In this section, you'll learn the ins and outs of writing a test with Playwright:

- Best practices for setup before running tests
- Simulating user actions like interacting with the UI to perform a search
- Creating a new user in the database
- Cleaning up after tests have run
- Using playwright fixtures for reliable setup/teardown

## Mocking & Authentication for E2E Tests

When your application relies on external services, you need to have a way to test them without actually using them. Similarly, you don't want to fully onboard a new account every time you test an authenticated user flow. In this section, you'll learn how to re-use the same mocks we’ve been using for development to mock third-party services and simulate logging in:

- Use Mock Service Worker to intercept network requests
- Replace email verification with a local file solution
- Attach cookies to Playwright
- Reusing 2FA logic for local testing
- Testing behavior with different HTTP responses

## Unit Testing

Sometimes you’ve got some really complicated business logic in your app. Business logic that is critical to your application. For this stuff, it’s nice to package it up in its own function or module to keep all that logic in one place. This is the perfect situation where lower level unit testing comes in handy. Here, we'll dive into unit testing with the Vitest framework to ensure that each function and module behaves as expected:

- Organizational best practices
- Asserting outcomes with `expect`
- Recording function calls with spies
- Specifying test behavior with Vitest hooks
- Keeping test output clean to avoid cluttering up the terminal

## Component and Hook Testing

When building React components, you should focus on two users: the user who interacts with a component, and the developer who renders it. By using Testing Library, we can avoid mocking React and its hooks and instead test components as they would be used in a real app:

- Render components with Testing Library
- Simulate the DOM environment on a per-test basis
- Querying for missing elements
- Testing hooks in isolation from React
- Stubbing React context
- Cleanup after testing

## Authenticated Integration

Similar to higher-level E2E tests, it is often necessary to simulate an authenticated user. However, we don't want to test the entire user flow every time we make a change. In this section, you'll learn how to test authenticated operations without the overhead of a full E2E test:

- Generating random session IDs
- Associating sessions with users
- Testing authenticated routes
- Asserting user state in responses

## Custom Assertions

Writing tests is good; writing readable and maintainable tests is better. Custom assertions can make your test code easier to understand and modify. Here you'll learn to encapsulate complex checks into simple, understandable assertions:

- Create matchers for specific states
- Share assertions across tests
- Add custom assertions to TypeScript definitions
- Format test output with colors for readability

## Test Database

There are some decisions to make when writing tests that interact with the database. Testing with the development database has benefits, but requires us to remember to delete data after each test. By using a test database, we can avoid accidents while still being able to run our test suites:

- Set up a test-specific database instance
- Seeding a minimal amount of data
- Defining a global setup for Vitest
- Understanding the importance of module import order

Learn how to write tests that cover all of your backend and frontend code. Web Application Testing covers unit testing, E2E, integration testing, and more!

Web Application Testing

Kent C. Dodds

Full Stack Vol 1

Intro to Web Application Testing Workshop

Intro to Web Application Testing 

Intro to End-to-End

Automate tests seamlessly in Playwright UI mode, mirroring manual tester actions. Validate search feature with Playwright's robust tools and intuitive interface

Playwright tests for user interactions, page navigation, search box inputs, and assert URLs, list elements, and items to test web app search functionality.

Writing and Asserting Playwright Tests for Search Functionality

Writing Automated Tests with Playwright UI Mode

Master isolated tests in Playwright and Node for better control, independence, and reliability. Import and run essential APIs for self-sufficient testing.

Create, manipulate URL with search parameters, display user data using encoding. Elevate your app's user data handling skills.

Creating and Interacting with User Data

Isolating Tests for Better Reliability and Flexibility

Clean up test data to maintain test isolation in end-to-end testing. Prevent data buildup in the development database, ensuring smooth, reliable workflows.

Incorporate user deletion in setup and teardown for a pristine testing environment, eliminating unwanted data and ensuring a clean slate for every test.

Proper Setup and Teardown of Testing for Database Cleanup

Test Isolation in End-to-End Testing

Utilize Playwright fixtures to guarantee thorough database cleanup, eradicating test-created user data, bypassing potential pitfalls from alternative methods.

Use Playwright fixtures for custom test objects, properties, behaviors, execute functions strategically, and manage data cleanup efficiently.

Playwright Fixtures for Testing

Implementing Fixtures to Ensure User Deletion in Playwright Tests

Take a break, nourish yourself, hydrate, and jot down your learnings to keep your brain sharp. Let's continue the great work with more testing ahead!

Dad Joke Break E2E

End-to-End

Address HTTP/S validity with a mock server and stub, this makes it easy to ensure that a client's response is consistent

Intro to E2E Mocking

Capture, save verification codes for smooth server-test automation communication.

Master Node.js email read/write with the File System module. Save, retrieve email data for testing efficiently.

Handling Emails in Node.js using File System

Writing Emails to the File System for Test Automation

Quickly grasp requiring and using disk-stored email data in tests for successful content reading. Crucial for test setup and execution.

Enhance process-to-process communication in Node.js using the secure file system method. Elevate data transfer and parsing capabilities.

Communicating Between Processes with File System in Node.js

Reading Email from Disk in Test Environment

Quickthink about the punning methods you will employ to share skeins of mirth with your fellow yo-cards

Dad Joke Break E2E Mocking

End-to-End Mocking

Learn how to simulate an authenticated user in your tests by generating and adding cookies to the browser context, improving test efficiency and isolation.

Intro to Auth E2E

Master end-to-end user flow tests, streamline authentication, and navigate login, profile editing, 2FA, and login verification.

Simulate user login, set cookies in browser tests to mimic web app authentication accurately.

Login and Setting Cookies for Browser Testing

End-to-End User Flow Testing and Authentication Utility

Dad Joke Break Auth E2E

Authenticated End-to-End

Intro to Unit Test

Craft solid unit tests for getErrorMessage, covering various scenarios and input-based error messages. Test pure and impure aspects thoroughly.

Master unit testing for utility functions, cover error handling, and achieve full code coverage with tools like coverage reports.

Writing Unit Tests for Utility Functions

Unit Testing a Function for Error Messages

Minimize test output logs, mock console.error for cleaner testing. Master spies for focused, effective testing without excessive console noise.

Utilize spies to track, assert console.error calls in tests. Ensure correct arguments and preserve valuable error info.

Testing Console Error with Spies

Managing Test Output and Error Logging with Console Mocking

Utilize Playwright testing hooks for error restoration and default mock restoration to enhance test stability.

Learn how to restore mocks by default, capture and handle console errors, and create a shared console error setup for efficient JavaScript testing.

Effective Error Handling and Console Capture Testing

Implementing Test Hooks for Error Restoration in Playwright

Create a setup file for automatic inclusion of essential files in all test files, closely simulating the production environment for effective testing.

Set up a test directory with setup files using VTest to automate configuration and common tasks. Ensure smooth test execution and robust error handling.

Setting Up Test Environment and Utilizing Setup Files with VTest

Creating a Setup File for Test Environment Setup

Dad Joke Break Unit Test

Unit Testing

Intro to Component Testing

Efficiently test Error List component rendering with React Testing Library. Gain hands-on experience across diverse test cases.

Simulate DOM with JSDOM for React component testing, skip the browser. Utilize Testing Library, tackle challenges, and hone your skills.

Testing React Components with JSDOM

Error List Component with React Testing Library

Fix test failures from DOM manipulation with proper cleanup techniques for reliable, efficient testing.

Maintain test isolation, eliminate dependencies on test state, and ensure clean execution in Testing Library with effective test cleanup.

Ensuring Isolation and Proper Test Execution

Proper DOM Cleanup for Reliable Testing

Dad Joke Break Component Test

Component Testing

Intro to Hooks

Create a double confirmation feature in React with a custom hook. Explore implementation,testing with RenderHook and Act. Prevent accidental actions effectively

Master custom React hook testing with RenderHook and Act from Testing Library React. Access hook properties through result.current for precise testing.

Testing Custom React Hooks with RenderHook and Act

Double Confirmation Feature

Test hooks with flexibility. Use custom test components or the render hook utility. Tailor your approach to your testing needs and preferences.

Create test components for thorough React hook testing, ensuring API contracts, and validating state changes accurately with Testing Library React and UserEvent

Testing React Hooks

Custom Test Components vs Render Hook Utility

Dad Joke Break Hooks

Hooks

Ensure test-driven development (TDD) by writing testcases from the get-go and developing integration tests quickly in isolation.

Intro to Testing Remix 

Fix a failing test by adding a parent route granting access to root data. Ensure proper rendering and testing of the username route in authenticated settings.

Create authenticated integration tests in Remix by configuring root routes, loaders, and context for precise testing of user interactions.

Creating Routes and Context in Remix

Creating a Parent Route for Accessing Root Data

We interrupt your couch time for this important reminder. Oh, and to keep you feeling healthy and vibrant.

Dad Joke Break Testing Remix 

Testing Remix

Learn how to mock APIs using MSW to enhance testing reliability, handle different scenarios, avoid dependencies, and ensure test isolation.

Intro to Http Mocking

Manually test and modify GitHub sign-in callback in your app. Adjust user association, validate response cookies, and location headers for robust functionality.

Simulate OAuth2 flow, effectively mock GitHub API requests in tests. Ensure robust verification of authentication and API integration in your app.

Testing OAuth2 Flow and Mocking GitHub API Responses

GitHub Sign-In Callback

Override HTTP interceptors for GitHub API token requests in testing, handle errors efficiently, export and access the server, and implement cleanup.

Master error case testing in a mock API environment. Verify failure handling, page redirection, and console error capture. Maintain test isolation with cleanup.

Testing Error Handling and Assertions with Mock API Calls

Testing Error Handling in GitHub API Interceptor

Learn how to avoid repeating test code by creating reusable functions and avoiding excessive duplication, ensuring efficient and maintainable testing workflows.

Organize code better with bottom setup functions, reduce repetition, and boost readability through parameterization and code sharing.

Efficient Code Organization with Setup Functions

Streamlining Repetitive Test Setup for Optimal Efficiency

Dad Joke Break Http Mocking

HTTP Mocking

Intro to Auth Integration

Master testing authenticated requests & connections post-login. Simulate sessions, verify for code reliability.

Master user setup, authenticate, and manage connections, including GitHub and DB users, sessions, and test cleanup. Deep dive into authentication.

Creating and Authenticating Users for Connection Setup

Testing Authenticated Requests and Connection Creation

Verify GitHub login session creation with assertions. Cover scenarios like connecting accounts and non-logged-in users.

Extract, check, parse server response's session cookie for user authentication, ensuring DB session creation.

Verifying Session Creation and User Authentication

Assertions for GitHub Login Session Creation

Swap fake data with real user info in routes, use utilities for seamless database user insertion and deletion.

Real DB interactions for user creation/deletion, image addition, request authentication in integration tests. Full UI coverage, no heavy mocking.

Authentication in Database Integration Tests

Integrating Real Database with User Routes

Dad Joke Break Auth Integration

Authenticated Integration

sanityVideoMuxId: gndUuMl8O02HCDPqYUGRa1o2oUxoiYsRoakUQ802ZtPnc

Intro to Custom Assertions

Enhance test assertion readability and functionality by creating custom matchers like assertRedirect. Elevate code clarity and error messages.

Elevate your testing game with custom assertions in Jest. Create "to have redirect" and more for precision. Organize in a test util directory for collaboration.

Custom Assertions with Jest's Expect Library

Custom Matchers for Assertions

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Dad Joke Break Custom Assertions

Custom Assertions

Extend the Gradle plugin to suit the needs of your projects. Learn about exploring a Cucumber-JVM Gradle boolean condition or approach using

Intro to Test Database

Set a test database with a URL before importing Prisma for seamless client testing. Master import order and setup for success.

Learn how to properly set up an isolated database for testing purposes using Prisma and dynamic imports, ensuring a clean and efficient testing environment.

Setting Up an Isolated Database for Tests

Setting Up a Test Database for Prisma Integration Tests

Learn how to solve conflicts when running tests simultaneously by setting up individual test databases to avoid shared state and data interference.

Learn how to create and manage isolated test databases using unique identifiers, allowing for efficient and independent testing processes.

Isolating Test Databases for Efficient Testing

Managing Test Databases for Parallel Testing

Speed up test execution with a global setup module. Enhance efficiency for faster, full database tests.

Learn how to set up a base database for faster test execution, avoiding repetitive migrations, and utilizing the real database environment efficiently.

Optimizing Test Setup with Global Database Configuration

Optimizing Test Setup

Take a well-deserved break before applying the acquired knowledge to your own projects. Well done!

Dad Joke Break Test Database

Test Database

Discover how to set up and integrate various testing tools, both at the UI and lower levels, to enhance your app's stability and facilitate easier test creation

Web Application Testing

Web Application Testing

Transcript

Creating a Stub for Testing Component Logic in Remix

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