class TermEntityReferenceTest

class TermEntityReferenceTest extends KernelTestBase {
    
    /**
     * {@inheritdoc}
     */
    protected static $modules = [
        'entity_test',
        'field',
        'system',
        'taxonomy',
        'text',
        'user',
    ];
    
    /**
     * {@inheritdoc}
     */
    protected function setUp() : void {
        parent::setUp();
        $this->installEntitySchema('entity_test');
        $this->installEntitySchema('taxonomy_term');
        $this->installEntitySchema('user');
    }
    
    /**
     * Tests an entity reference field restricted to a single vocabulary.
     *
     * Creates two vocabularies with a term, then set up the entity reference
     * field to limit the target vocabulary to one of them, ensuring that
     * the restriction applies.
     */
    public function testSelectionTestVocabularyRestriction() {
        // Create two vocabularies.
        $vocabulary = Vocabulary::create([
            'name' => 'test1',
            'vid' => 'test1',
        ]);
        $vocabulary->save();
        $vocabulary2 = Vocabulary::create([
            'name' => 'test2',
            'vid' => 'test2',
        ]);
        $vocabulary2->save();
        $term = Term::create([
            'name' => 'term1',
            'vid' => $vocabulary->id(),
        ]);
        $term->save();
        $term2 = Term::create([
            'name' => 'term2',
            'vid' => $vocabulary2->id(),
        ]);
        $term2->save();
        // Create an entity reference field.
        $field_name = 'taxonomy_' . $vocabulary->id();
        $field_storage = FieldStorageConfig::create([
            'field_name' => $field_name,
            'entity_type' => 'entity_test',
            'translatable' => FALSE,
            'settings' => [
                'target_type' => 'taxonomy_term',
            ],
            'type' => 'entity_reference',
            'cardinality' => 1,
        ]);
        $field_storage->save();
        $field = FieldConfig::create([
            'field_storage' => $field_storage,
            'entity_type' => 'entity_test',
            'bundle' => 'test_bundle',
            'settings' => [
                'handler' => 'default',
                'handler_settings' => [
                    // Restrict selection of terms to a single vocabulary.
'target_bundles' => [
                        $vocabulary->id() => $vocabulary->id(),
                    ],
                ],
            ],
        ]);
        $field->save();
        $handler = $this->container
            ->get('plugin.manager.entity_reference_selection')
            ->getSelectionHandler($field);
        $result = $handler->getReferenceableEntities();
        $expected_result = [
            $vocabulary->id() => [
                $term->id() => $term->getName(),
            ],
        ];
        $this->assertSame($expected_result, $result, 'Terms selection restricted to a single vocabulary.');
    }

}