Kernel tests in Drupal enable module integration testing with Drupal core systems in a bootstrapped environment. Kernel tests bridge the gap between unit and functional tests. This tutorial focuses on writing kernel tests for the anytown module, specifically to test the ForecastClient service's caching logic and custom username validation.

In this tutorial, we'll:

• Explore the parts of a kernel test.
• Write kernel tests for anytown module features.
• Use mocks and the Drupal container in kernel tests.

By the end of this tutorial, you should be able to get started writing kernel tests to verify your module's integration with Drupal core.

Unit tests are the simplest among Drupal's test types, ideal for verifying code that performs computations. This tutorial guides through writing unit tests for the anytown module, focusing on the ForecastClient service, and illustrates how to use mocks for dependencies.

In this tutorial, we'll:

• List potential unit tests for the anytown module.
• Write tests for ForecastClient service logic.
• Demonstrate how to mock services in unit tests.

By the end of this tutorial you should be able to write PHPUnit Unit tests for logic in the anytown module.

As of Drupal 10.2, most plugin types use PHP attributes for discovery and metadata.

In this tutorial, we'll:

• Provide a recipe for implementing PHP attribute-based plugins.
• Demonstrate how to figure out where the code and metadata should live for PHP attribute-based plugins.

By the end of this tutorial you should have a recipe for getting started with implementing PHP attribute-based plugins, and a better understanding of how to figure out the details required to implement a given plugin type.

PHP attributes are a native PHP language feature, introduced in PHP 8.0, that provide a way to add metadata to classes, methods, properties, and functions in PHP code.

In Drupal, this metadata is used by the plugin system to aid in the discovery and configuration of plugin instances. As a Drupal developer, it's important to understand how to recognize, read, and write PHP attributes, as you'll encounter them when working with plugins.

In this tutorial we'll look at:

• What PHP attributes are
• The use case for attributes in Drupal
• An overview of the attribute syntax

By the end of this tutorial, you should understand how attributes are used in Drupal and how to write them in your own code.

Prior to Drupal 10.2 most plugin implementations required the use of annotations alongside a PHP class. Now Drupal supports and recommends the use of PHP attributes instead. During the transition, most developers will still need to know how to recognize and implement annotation-based plugins.

In this tutorial we'll:

• Provide a recipe for implementing annotation-based plugins.
• Demonstrate how to figure out where the code and metadata should live for annotation-based plugins.

By the end of this tutorial you should have a recipe for getting started with implementing annotation-based plugins, and a better understanding of how to figure out the details required to implement a given plugin type.

Many of Drupal's APIs that look like a bunch of configuration in a YAML file (migrations, menu links, etc.) are actually plugins in disguise. The YAML from these files is used as arguments to a generic PHP plugin class which then behaves differently depending on the provided values. As a developer, you probably don't need to know that menu links are plugins, but it can be helpful when debugging or just trying to get a better understanding of the big picture.

In this tutorial, we'll:

• Learn about how YAML-based plugins work
• Discuss how to find the implementation details for YAML-based plugins
• Walk through an example of implementing a YAML-based plugin

By the end of this tutorial, you should be able to recognize a YAML-based plugin definition, and author your own.

There’s no one-size-fits-all path to upgrade from Drupal 10 to Drupal 11, but there is a set of common tasks that everyone will need to complete.

In this tutorial we’ll:

• Explain the differences between Drupal 10 and Drupal 11 that affect the upgrade path.
• Walk through the high-level steps required to upgrade from Drupal 10 to Drupal 11.
• Provide resources to help you create an upgrade checklist and start checking items off the list.

By the end of this tutorial you should be able to:

• Explain the major differences between Drupal 10 and 11.
• Audit your existing Drupal 10 projects for Drupal 11 readiness, and estimate the level of effort involved.
• Start the process of upgrading your site from Drupal 10 to Drupal 11.

In this tutorial, you’ll create and render a simple single directory component (SDC) in Drupal. You’ll set up the required files, call the component from a template, and confirm that Drupal renders it with its styles automatically attached.

By following along, you will:

• Scaffold the files for a basic card component.
• Reference the component in a node template.
• See how Drupal renders the component’s HTML and CSS together.

When you’re done, you’ll have a complete working example of a Drupal single directory component.

The component YAML file, with the suffix .component.yml, is the heart of every Drupal single directory component (SDC). This file describes how consumers can pass data (props) and nest content (slots) into the component. Similar to a PHP interface, the schema defined in a .component.yml file acts as a contract that tells consumers (both developers and low-code tools) what data a component accepts and what shape it expects.

In this tutorial, you’ll learn what each key in a component's YAML file does. You’ll see how the file names the component, describes its API, and helps low-code tools validate and expose your component. Then we’ll create a new card component with a card.component.yml file.

By following along, you will:

• Reinforce your understanding of where a Drupal component's YAML file lives and why it matters.
• Break down each top-level key—$schema, name, description, props, and slots.
• Learn more about what you can put into a .component.yml file.

By the end of this tutorial, you’ll have a discoverable card.component.yml file for a new card SDC and a mental model for how Drupal uses it.

Learn how to embed a Drupal single directory component (SDC) in a Twig template like node.html.twig. This tutorial explains how to pass props and slots to the component, how to determine the correct namespace and name, and how to choose between Twig’s {% include %} and {% embed %} when rendering an SDC. This technique is most often used by theme developers who override templates and compose a page using single directory components. A common scenario is expressing your design system as components in a theme, then overriding templates to use those components.

In this tutorial, we will:

• Reference a component from a parent Twig template file.
• Pass props and slot values to a component from that template.
• Decide when to use {% include %} or {% embed %} based on the component's slot structure.

By the end of this tutorial, you’ll be able to embed a component into a Twig template and pass values to both its props and slots.

As a module developer, you output themed content from your module in the form of renderable arrays. When doing so, you can make use of single directory components (SDCs) by using the #type => 'component' render element type. This allows modules to dynamically select and configure a component based on configuration or specific PHP logic. You'll use this as the return value of a controller, or a configurable plugin related to display building, like custom blocks or field formatters. As an example, we'll author a custom block plugin that loads a specific node and outputs it using the card SDC we defined in a previous tutorial. We'll build a render array that supplies the values for the component's props and slots, and add some caching logic to the output.

In this tutorial, we will:

• Build a render array that targets an SDC via the #component property.
• Pass data into the component's props and slots, and demonstrate optional #propsAlter and #slotsAlter callbacks.
• Validate the output and cache it properly.

By the end of this tutorial, you'll be able to render any SDC via a module's PHP code using a well-structured and cache-friendly render array.

One of the benefits of using Drupal single directory components is that Drupal automatically builds and attaches an asset library whenever it is used. Adding CSS styles and JavaScript interactivity to a single directory component (SDC) is as simple as dropping component-name.css and component-name.js files into the root directory of the component. Drupal detects these files, creates an asset library, and attaches it when the component is rendered. This means when you want to add additional CSS or JavaScript assets, you will override the asset library created for your component instead of defining a new one.

In this tutorial, we will:

• Add component-scoped CSS and JavaScript files.
• Learn how to override a component's existing asset library to add additional assets.
• Discuss how to integrate common front-end asset build tools (Gulp, Webpack, Vite, etc.) while working with Drupal single directory components.

By the end of this tutorial, you'll be able to attach CSS and JavaScript assets to an SDC and validate that they load only when the component is in use.

Drupal single directory components use Twig template files to define their HTML markup and how the values of props and slots are displayed. To discover available props and slots, read the component’s .component.yml file. When working with slots, you’ll often choose between rendering a slot as a Twig block ({% block %}) or interpolating a variable directly ({{ variable }}).

In this tutorial, you’ll:

• Add a card.twig file to an existing component directory.
• Read the associated card.component.yml schema to identify props and slots you can work with.
• Render props and slots wrapped in custom HTML markup.

By the end of this tutorial, you’ll be able to connect a Twig template to any SDC and render the props and slots passed into the component.

A Drupal single directory component (SDC) is Drupal's way of packaging the markup, metadata, styles, and behavior for a UI element in one self-contained folder inside a theme or module. This structure helps front-end developers and site builders keep all related files together for easier theming and reuse. A Drupal single directory component directory must be located in a specific place and its files named with a particular convention so that the system can discover it and use its assets.

In this tutorial, we'll:

• Show where Drupal discovers single directory components in your codebase.
• Explain the naming and organization conventions for Drupal single directory component directories and files.
• Outline key files for a component—both required and optional.

By the end of this tutorial, you'll be able to identify an SDC directory in a Drupal module or theme and know exactly what you're looking at.

Using Vite we can scaffold a stand-alone React application with modern tooling, instant dev-server startup, and hot module replacement. It's a great way to get started with React and works perfectly for decoupled apps that talk to Drupal's JSON:API. After creating the scaffold, we'll port code from previous tutorials to the new structure.

In this tutorial we'll:

• Use Vite to scaffold a new React project
• Refactor existing code into Vite's project structure
• Confirm that our code runs

By the end of this tutorial, you'll know what Vite is and how to get started using it for a decoupled React app.

Props and slots are the two ways that data can be provided to a single directory component (SDC). They are part of a component's schema definition, and are used to determine the names of variables passed to a component's template file. Props pass structured, validated data into a component, while slots allow us to inject flexible content such as HTML or nested components. Understanding when and how to use each ensures you can build reusable and adaptable components.

In this tutorial, we'll:

• Learn what props and slots are, and how they differ.
• Discuss how using one or the other impacts the developer experience and use of your components in a UI.
• Practice deciding when to use each for component design.

By the end of this tutorial, you'll know how to choose between props and slots when building components.

Overriding Single Directory Components (SDCs) allows you to safely customize the functionality and appearance of components provided by contrib modules or themes. Instead of editing the original files, copy a component into your theme, declare that it replaces the original, and then make the necessary adjustments. This approach ensures our changes are upgrade-safe and easy to maintain.

In this tutorial, we will:

• Copy an existing SDC into a theme.
• Use the replaces: key in the component metadata to declare the override.
• Modify the component Twig, CSS, or JavaScript and confirm the changes appear on our site.

By the end of this tutorial, you should be able to override SDCs safely and maintain your customizations in an upgrade-safe manner.

Learn how to generate menu links dynamically with plugin derivatives in a custom module. This tutorial walks through creating a single base menu link plugin definition and a deriver class that expands that definition into one menu link per content entity. The code will automatically generate links for all published basic pages, placing dynamic menu links in the main menu.

By the end of this tutorial, you should be able to:

• Understand which files you need in order to define menu link plugin derivatives, also known as dynamic menu links
• Create the necessary code to define menu link plugin derivatives for an example use case

This reference document contains a detailed list of available properties for the #[ContentEntityType] attribute in Drupal 11. The current documentation in the Drupal 11 code base lists, but doesn't always describe, each of these properties. Or, in many cases, the property is an associative array where the nested key/value pairs are important, but what they should be isn't well documented. So we've created this helpful reference. Most of the properties listed here will also apply to #[ConfigEntityType] attributes. These properties define the metadata and behavior of custom entity types.

In this tutorial, we'll:

• Look at an example of how to use #[ContentEntityType] attributes.
• Provide a comprehensive list of available properties and a description of each.
• Show detailed examples of using nested array properties like handlers[].

By the end of this tutorial, you should be able to understand how and when to use any of the properties of a #[ContentEntityType] attribute in order to modify the behavior of a custom entity type.

Drupal stores the settings that define how a site behaves as configuration data. Everything from the site name to image styles, roles, and view definitions are stored as configuration. The Configuration API gives modules, themes, and installation profiles a consistent way to store, retrieve, update, and provide this configuration in a structured and portable way.

In this tutorial, we'll:

• Provide a high-level overview of the features of Drupal's Configuration API
• Link to related tutorials where you can learn more and get hands-on practice working with configuration data in code.