In this gentle introduction to testing, we'll walk through what testing is and why it's important to your project. Then we'll define some terms you'll be likely to see while working with tests so that we're all on the same page. After reading through this tutorial you'll understand enough of the basic vocabulary to get started running (and eventually writing) tests for your Drupal site.

The testing suite for the Drupalize.Me site uses a different strategy for functional JavaScript testing. We use a tool called Nightwatch.js that allows us to write our tests in JavaScript that runs commands against a web browser. This browser automation allows us to test the types of interactions that a typical user of our website might encounter. It also allows us to test JavaScript code using JavaScript, and execute our tests in different browsers. In this tutorial we'll take a look at how to set up Nightwatch.js, and what the syntax looks like for a couple of basic tests.

In order for Drupal to be able to locate and run the tests you create, the files need to be put in the correct place. In this tutorial, we'll take a look at the different types of test frameworks that are included along with core. We'll also see how Drupal expects our test files to be organized so that the test runners can find them.

When running tests with PHPUnit we need to specify a phpunit.xml file that contains the configuration that we want to use. Often times (and in much of the existing documentation) the recommendation is to copy the core/phpunit.xml.dist file to core/phpunit.xml and make your changes there. And this works fine, until something like a composer install or composer update ends up deleting your modified file. Instead, you should copy the file to a different location in your project and commit it to your version control repository.

In this tutorial we'll:

• Learn how to move, and modify, the phpunit.xml.dist file provided by Drupal core
• Understand the benefits of doing so
• Demonstrate how to run phpunit with an alternative configuration file

By the end of this tutorial you should be able to commit your phpunit.xml configuration file to your project's Git repository and ensure it doesn't get accidentally deleted.

In this tutorial, we'll run tests in several different ways using the PHPUnit tools available in Drupal. We'll learn about various environment variables you'll need to supply to the test runner depending on which type of test you're running. And we'll learn various ways to get reports on the test results. By the end of this tutorial, you should understand how to run Drupal tests using PHPUnit.

Drupal core comes with a run-tests.sh script to help with running tests. This script has some distinct advantages over running tests directly via PHPUnit. It runs all tests in their own separate process, and can therefore handle PHP fatal errors without killing the test run. It's also the mechanism that the Drupal CI tools use to run tests; so, it can be handy when debugging tests that are failing on Drupal.org.

In this tutorial we'll:

• Look at the available options for the core run-tests.sh script
• Go through some examples of running tests using run-tests.sh

By the end of this tutorial you'll know how to run your tests using run-test.sh.

In this tutorial, we'll walk through the process of setting up a functional test. Then, we'll learn how to run it using two different test runners. This setup process allows us to be sure we're not getting false positives from the test runners. We'll be working on a functional test, but these techniques apply with minimum modification to all the Drupal PHPUnit-based tests.

By the end of this tutorial, you should be able to set up and run functional tests in Drupal using two different test runners.

This tutorial will clarify some basic ideas about software testing. We'll give some strategies for testing and illustrate types of tests and when and why you'd use them. This document is written with Drupal in mind, but the concepts apply for other development environments you'll encounter as well. The tools will be different, but the ideas apply universally. By the end of this tutorial, you should understand what testing is for and how different types of tests support different purposes and outcomes.

In order to run functional tests that require JavaScript be executed for the feature to work, the tests need to be run in a browser that supports JavaScript. This is accomplished by using the WebDriver API in combination with an application like ChromeDriver or Selenium, which can remotely control a browser.

The exact setup for running functional tests is dependent on your development environment. We'll walk through a couple of common examples including using Docker (via DDEV) and stand-alone applications.

In this tutorial we'll:

• Learn how to install and run ChromeDriver and other necessary tools either in a Docker environment, or locally.
• Configure the relevant PHPUnit environment variables so they contain values appropriate for our specific environment.
• Execute Drupal's functional JavaScript tests via the phpunit command.

By the end of this tutorial you should be able to install the applications required to run functional JavaScript tests in a browser, and know how to configure PHPUnit to make use of them.

Themes and modules can alter the list of theme hook suggestions in order to add new ones, remove existing ones, or reorder the list. This powerful feature allows for the definition of custom logic in your application that can tell Drupal to use different templates based on your own unique needs. You might for example; use a different page template for authenticated users, or a custom block template for someone's birthday.

In this tutorial we'll cover:

• Adding new theme hook suggestions from a theme using hook_theme_suggestions_HOOK_alter()
• Altering the list of theme hook suggestions
• Removing theme hook suggestions
• Reordering the list of theme hook suggestions

In Drupal's Appearance UI, all themes get a theme settings form. As a theme developer, you can customize the theme settings form, enabling site administrators to have more control over the appearance of the theme.

In this tutorial, we'll show you how to add admin-configurable settings to your theme. In the process of doing this, we'll use a variety of theme and module development skills and assume you have some familiarity with using Drupal's Form API, Configuration API, and theme system (see Prerequisites).

By the end of this tutorial, you will be able to provide custom theme settings that an administrator can use to modify the appearance of the theme.

Any text that will be displayed to user as part of your application's user interface should be passed through the t() function, or an equivalent, so that it can be translated into other languages as needed. This tutorial will look at how to use the t() function.

This tutorial contains information that applies to anyone writing modules or themes. And many of the tutorials you read on this site and on the web in general will expect that you understand how basic string translation works.

In this tutorial we'll look at:

• Passing strings through the t() function or equivalent so they are available for translation
• Using placeholders for dynamic content in translatable strings
• Tips for making your code's interface strings easier to translate

Before you can create a path or link to another page on your site, you'll need to know the route (unless there is already a variable available for the URL you need). Finding a route can be a tricky task unless you have the right tools. In this tutorial, we'll show how tools like Webprofiler, Drush, and Grep can be used to get route information for a page, so that you can use functions that need a route as a function parameter.

In this tutorial we'll:

• Learn how to determine the route or path of an internal page.

In this tutorial, we'll walk through the process of adding and configuring filters and adding a filter group.

In this tutorial, we'll walk through the process of adding and configuring sort criteria to a view.

In this tutorial, we'll add and configure a contextual filter for a view. Our Baseball Awards content type has a field Year. We'll make it possible for a page to be dynamically created on our site that contains the year and lists the awards for that specific year. To do this, we'll add a contextual filter to the Baseball Awards view that will allow visitors to filter the list of awards by the award year. We'll also add a block using the summary view contextual filter configuration, which visitors can use to view results for specific years.

One of the ways you can create a REST endpoint in Drupal is by using Views. In this tutorial, we'll add a REST endpoint display to a view of baseball players. We'll examine and configure settings that are unique to the REST endpoint display.

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

• Add a REST endpoint display to a view
• Understand how to configure settings for an endpoint

Instead of providing multiple views with different filter criteria, consider empowering your users by exposing filter criteria as an interactive form. You can even configure the forms to use AJAX to refresh results. In this tutorial, we'll walk through the process of adding and configuring exposed filter or sort criteria in a view.

Like exposed filters, we can expose sort criteria to the site visitor. Exposing sort criteria gives the visitor more control over the list of content they are viewing. In this tutorial, we'll configure our view of baseball players to allow visitors to sort the list in different ways by adding several exposed sort criteria.

Contextual filters are a Views mechanism for dynamically refining the contents of a view. It might be helpful to think of them as "dynamic filters". In this tutorial, we'll discuss the concept of context, look at how to add contextual filters in the Views UI, and review the Taxonomy term view that comes with Drupal and how it uses a contextual filter.