When developing a Drupal site, it is best practice to maintain multiple environments: A production environment for your live site, a stage environment for “next version” development, and your local environment for debugging and creating new features. Solr adds further complexity as we should have a separate Solr server for each.

In this tutorial, we'll:

• Describe why different Solr servers should be used for each environment
• Explain why Config Split is not a solution for multiple environments
• Describe how to use config overrides for each environment

By the end of this tutorial you should be able to override your Search API server configuration with environment-specific settings.

While Solr compartmentalizes settings into cores, Search API organizes things into indexes. Each Search API index can have a unique set of settings and crawl a specified list of content types. Search API indexes can be created in the Search API admin interface.

In this tutorial, we'll:

• Identify a Search API index
• Describe how an index is related to a Solr core

By the end of this tutorial you should be able to create a new Search API Index connected to a Solr backend.

Creating an index alone is not enough. To populate the index, we need to specify the fields necessary to populate the index. Selecting the fields is accomplished in the Search API admin UI.

In this tutorial, we'll:

• Explain how to select what populates a search index
• Describe a field boost, and how it is used to customize results

By the end of this tutorial you should be able to add fields to a Search API Index so their content is available for searching, and then instruct Search API to index the content of your site.

Reference field types, such as taxonomy term fields, paragraph fields, or plain entity reference fields, refer to a completely separate entity within the site. This makes search configuration complicated as the typical scope of a search crawl is on a per-node (really a per-entity) basis. Fortunately there are known strategies to index these fields with ease.

In this tutorial, we'll:

• Describe why reference types pose a particular challenge to indexing
• Discuss the importance of display modes in indexing
• Highlight how the Rendered HTML Output field can be used to index paragraphs

By the end of this tutorial you should be able to add reference fields to your Search API Index and allow users to search their contents in the correct context.

One of Search API’s key advantages is that custom search pages can be created using Views. This allows a high degree of customization, while relying on a familiar toolset.

In this tutorial, we'll:

• Describe how to use Views to create a search page
• Explain search page best practices, including requiring input and no-results text

By the end of this tutorial you should be able to create a page that users can use to search your site's content using the Solr search backend.

Drupal has the ability to support multiple Search API indexes within a single installation. While adding a new index is easy, we must understand the implications of creating and using multiple Search API indexes.

In this tutorial, we'll:

• Identify when to create multiple indexes in Search API
• Define virtual indexes, and their performance implications

Processors allow you to augment your search indexes by performing additional operations before or after the index operation. This can make your search more flexible.

In this tutorial, we'll:

• Identify what a processor is, and when it can be employed in the search pipeline.
• List useful processors provided by Search API.
• Describe how to apply a processor to an index, and why reindexing is necessary.

Excerpts are brief snippets of text displayed in search results. They give context to how the search terms relate to the result. Search API provides support for excerpts out of the box.

In this tutorial, we'll:

• Identify how to apply excerpts to a search index
• Describe how to add excerpt display to the search view

By the end of this tutorial you should be able to use the Highlight search processor to add excerpts to search results.

Autocomplete provides a brief and quick list of results to the user while typing. While this functionality isn’t available out of the box, it’s easy to add using an additional contributed module, Search API Autocomplete.

In this tutorial, we'll:

• Describe how to add autocomplete functionality to an existing index

By the end of this tutorial you should be able to add an autocomplete feature to the search query text field.

One of the key advantages of custom search is to do more than provide a single, global search box. Filtering allows you to divide results to a subset.

In this tutorial, we'll:

• Describe how to configure filtering through use of a taxonomy field
• Explain the disadvantages of this approach, including how it relies on Views to reduce results rather than Solr

Filtering results allows us to divide up the result set along one or more dimensions. It’s built in to Search API, but often we need a slightly different approach. Drill-down search or faceted searching allows us to constrain (rather than divide) our result set to one or more dimensions. The contributed Facets module provides this functionality.

In this tutorial, we'll:

• Describe how facets constrains results to preconfigured dimensions
• Demonstrate how use of a facet also constrains the possible selections for other facets
• List the steps for installing Facets module
• Describe the field types best used for creating facets

By the end of this tutorial you should be able to explain what facets are and how they work in the context of searching a Drupal site's content.

Creating a facet in Drupal is rather different from using Facets API in Drupal 7. In the new module, we first create a search view, and then configure facets against target fields in the index. Once created, we must configure the facet UI to appear on target pages using the Blocks UI.

In this tutorial, we'll:

• List the steps necessary to create a facet using a non-reference field (i.e. boolean, or text list)
• Explain why facets are displayed using blocks
• Describe the various facet display modes and uses for each

By the end of this tutorial you should be able to add a facet based on a text list field and allow users to filter search results using the values in the list field.

A powerful facet combination is to create a search Facet on a taxonomy field. This brings several advantages to how your search can be configured and displayed.

In this tutorial, we'll:

• Describe the additional complexities for using a reference field for a facet
• Show how to use taxonomy weights to control facet option order

By the end of this tutorial you should be able to add a facet that allows users to filter search result based on taxonomy terms.

In order to run tests, your Drupal site needs additional development requirements installed using Composer.

By default, when you download Drupal as a zip file or tarball, these packages will not be installed, since they're used for development purposes.

In this tutorial, we'll walk through the steps to make sure we've got Composer available. Next we'll install the dependencies. Then we'll talk about why you shouldn't have development dependencies available on your production site. Thankfully, Composer can help make this easy to manage.

Simpletest has been removed from Drupal 9. If you're preparing to upgrade your site to the latest version of Drupal and you have Simpletests in your codebase that extend WebTestBase you'll need to update them to use PHPUnit's BrowserTestBase class instead. This will ensure your tests don't depend on a deprecated testing framework. By the end of this tutorial, you should be able to convert WebTestBase-based tests to use PHPUnit's BrowserTestBase class instead.

In this tutorial, we will look at the various types of tests and testing frameworks included in Drupal core. We'll also provide an overview of how the different frameworks operate and the types of situations where each of the different frameworks is useful.

Previously, in Implement a Functional Test, we learned how to tell BrowserTestBase to use the Standard installation profile in order to get our test passing, letting the Standard profile implicitly provide our dependencies. We mentioned that doing so probably wasn't the best decision and that we should explicitly declare those dependencies instead.

In this tutorial, we'll walk through how to explicitly declare our test's dependencies. When in doubt, it's generally considered a best practice to be as explicit about the dependencies of our tests as possible. By the end of this tutorial, you should be able to:

• Understand why we want to explicitly declare our dependencies.
• Determine what the dependencies really are and make a list of them.
• Implement each dependency in our list.
• Emerge with a thorough passing test.

In this tutorial, we'll walk through the basics of how to implement a functional test by extending Drupal's BrowserTestBase class. We'll assume you've already determined that you need to write a functional test and that you've Set up a Functional Test.

In this tutorial, we'll:

• Determine the specifications of the test.
• Walk through the behavior we want to test.
• Document our test in the test class.
• Implement the testing steps.
• Decide how to deal with dependencies (for now). (We'll go into details about handling test dependencies in Implement Drupal Functional Test Dependencies.)

Let's write somewhat strict unit tests in a Drupal module. By the end of this tutorial, you will be able to:

• Understand what makes a unit test different from other types of tests.
• Determine the specifications of a unit test.
• Use mocking to isolate units under test, and to force code flow to achieve high coverage.

We'll start out with a brief introduction to unit tests. Then we'll look at a contrived example of a Drupal controller class for illustration purposes. Next, we'll test two units of this controller class, each requiring different mock styles.

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.