Return a token with the name of a single guest

modules/opd_podcast/opd_podcast.module

@@ -2,7 +2,10 @@
 
 declare(strict_types=1);
 
+use Drupal\Core\Render\BubbleableMetadata;
+use Drupal\Core\StringTranslation\TranslatableMarkup;
 use Drupal\node\NodeInterface;
+use Drupal\taxonomy\TermInterface;
 
 /**
  * @param array<non-empty-string, array<non-empty-string, array{}>> $links
@@ -23,3 +26,66 @@ function opd_podcast_node_links_alter(array &$links, NodeInterface $entity, arra
   $links['#attributes']['class'][] = 'm-0';
   $links['#attributes']['class'][] = 'p-0';
 }
+
+/**
+ * Implements hook_token_info().
+ *
+ * @return array{tokens: array<non-empty-string, array{description: TranslatableMarkup, name: TranslatableMarkup}[]>, types: array<non-empty-string, array{description: TranslatableMarkup, name: TranslatableMarkup}>}
+ */
+function opd_podcast_token_info(): array {
+  $tokens = [];
+
+  $type = [
+    'description' => t('Tokens related to podcasts.'),
+    'name' => t('Podcasts'),
+  ];
+
+  $tokens['guest-names'] = [
+    'description' => t('The names of the guests on a podcast episode.'),
+    'name' => t('Guest names'),
+  ];
+
+  return [
+    'tokens' => [
+      'opd-podcast' => $tokens,
+    ],
+    'types' => [
+      'opd-podcast' => $type,
+    ],
+  ];
+}
+
+/**
+ * Implements hook_tokens().
+ *
+ * @param array<non-empty-string, non-empty-string> $tokens
+ * @param array<non-empty-string, mixed> $data
+ * @param array<non-empty-string, mixed> $options
+ *
+ * @return array<non-empty-string, mixed>
+ */
+function opd_podcast_tokens(string $type, array $tokens, array $data, array $options, BubbleableMetadata $bubbleableMetadata) : array {
+  $replacements = [];
+
+  if ($type === 'opd-podcast') {
+    foreach ($tokens as $name => $original) {
+      switch ($name) {
+        case 'guest-names':
+          $node = $data['node'] ?? NULL;
+          assert($node instanceof NodeInterface);
+          assert($node->hasField('field_podcast_guests'));
+
+          $guests = $node->get('field_podcast_guests')->referencedEntities();
+          assert(is_array($guests));
+          assert(!is_null($guests[0]));
+          assert($guests[0] instanceof TermInterface);
+
+          $replacements[$original] = $guests[0]->label();
+          break;
+      }
+    }
+  }
+
+  return $replacements;
+}
+

modules/opd_podcast/tests/modules/opd_podcast_test/config/install/field.field.node.podcast_episode.field_podcast_guests.yml

@@ -0,0 +1,28 @@
+langcode: en
+status: true
+dependencies:
+  config:
+    - field.storage.node.field_podcast_guests
+    - node.type.podcast_episode
+    - taxonomy.vocabulary.podcast_guest
+id: node.podcast_episode.field_podcast_guests
+field_name: field_podcast_guests
+entity_type: node
+bundle: podcast_episode
+label: Guests
+description: ''
+required: false
+translatable: false
+default_value: {  }
+default_value_callback: ''
+settings:
+  handler: 'default:taxonomy_term'
+  handler_settings:
+    target_bundles:
+      podcast_guest: podcast_guest
+    sort:
+      field: name
+      direction: asc
+    auto_create: true
+    auto_create_bundle: ''
+field_type: entity_reference

modules/opd_podcast/tests/modules/opd_podcast_test/config/install/field.storage.node.field_podcast_guests.yml

@@ -0,0 +1,19 @@
+langcode: en
+status: true
+dependencies:
+  module:
+    - node
+    - taxonomy
+id: node.field_podcast_guests
+field_name: field_podcast_guests
+entity_type: node
+type: entity_reference
+settings:
+  target_type: taxonomy_term
+module: core
+locked: false
+cardinality: -1
+translatable: true
+indexes: {  }
+persist_with_no_fields: false
+custom_storage: false

modules/opd_podcast/tests/modules/opd_podcast_test/config/install/node.type.podcast_episode.yml

@@ -0,0 +1,11 @@
+langcode: en
+status: true
+dependencies: { }
+third_party_settings: { }
+name: 'Podcast episode'
+type: podcast_episode
+description: null
+help: null
+new_revision: true
+preview_mode: 1
+display_submitted: true

modules/opd_podcast/tests/modules/opd_podcast_test/config/install/taxonomy.vocabulary.podcast_guest.yml

@@ -0,0 +1,8 @@
+langcode: en
+status: true
+dependencies: {  }
+name: 'Podcast guest'
+vid: podcast_guest
+description: null
+weight: 0
+new_revision: false

modules/opd_podcast/tests/modules/opd_podcast_test/opd_podcast_test.info.yml

@@ -0,0 +1,8 @@
+name: Podcast Test
+description: A test module for podcasts.
+core_version_requirement: ^11
+type: module
+package: oliverdavies.uk
+hidden: true
+dependencies:
+  - drupal:node

modules/opd_podcast/tests/src/Kernel/PodcastTokenTest.php

@@ -0,0 +1,75 @@
+<?php
+
+namespace Drupal\Tests\opd_podcast\Functional;
+
+use Drupal\Tests\BrowserTestBase;
+use Drupal\Tests\node\Traits\NodeCreationTrait;
+use Drupal\Tests\token\Functional\TokenTestTrait;
+use Drupal\node\NodeInterface;
+use Drupal\taxonomy\Entity\Term;
+use Drupal\taxonomy\TermInterface;
+
+class PodcastTokenTest extends BrowserTestBase {
+
+  use NodeCreationTrait;
+  use TokenTestTrait;
+
+  public $defaultTheme = 'stark';
+
+  protected static $modules = [
+    'opd_podcast',
+    'opd_podcast_test',
+    'taxonomy',
+  ];
+
+  /**
+   * @param non-empty-string[] $guestNames
+   * @param non-empty-string $expected
+   *
+   * @dataProvider podcastNodeProvider
+   */
+  public function test_guest_name_token(array $guestNames, string $expected): void {
+    $node = $this->createPodcastNode(
+      guestNames: $guestNames,
+    );
+
+    $this->assertToken(
+      data: ['node' => $node],
+      expected: $expected,
+      token: 'guest-names',
+      type: 'opd-podcast',
+    );
+  }
+
+  public function podcastNodeProvider(): \Generator {
+    return [
+      yield 'Single guest' => [['Matt Glaman'], 'Matt Glaman'],
+    ];
+  }
+
+  /**
+   * @param array<int, non-empty-string> $guestNames
+   *
+   * @return list<TermInterface>
+   */
+  private function createGuestTerms(array $guestNames): array {
+    return array_map(
+      array: $guestNames,
+      callback: fn (string $guestName): TermInterface => Term::create([
+        'name' => $guestName,
+        'vid' => 'podcast_guest',
+      ]),
+    );
+  }
+
+  /**
+   * @param non-empty-string[] $guestNames
+   */
+  private function createPodcastNode(array $guestNames): NodeInterface {
+    return $this->createNode([
+      'field_podcast_guests' => $this->createGuestTerms($guestNames),
+      'title' => '::title::',
+      'type' => 'podcast_episode',
+    ]);
+  }
+}