Add Tag transformer for WP_Term objects

.github/changelog/2552-from-description

@@ -0,0 +1,4 @@
+Significance: patch
+Type: added
+
+Adds support for turning tags, categories, and custom taxonomies into federated collections in the Reader view so you can browse and follow topics more seamlessly.

includes/transformer/class-factory.php

@@ -110,6 +110,8 @@ public static function get_transformer( $data ) {
 					return new User( $data );
 				}
 				break;
+			case 'WP_Term':
+				return new Term( $data );
 			case 'json':
 				return new Json( $data );
 		}

includes/transformer/class-term.php

@@ -0,0 +1,38 @@
+<?php
+/**
+ * Term Transformer Class file.
+ *
+ * @package Activitypub
+ */
+
+namespace Activitypub\Transformer;
+
+/**
+ * Term Transformer Class.
+ */
+class Term extends Base {
+	/**
+	 * Transforms the WP_Term object to an OrderedCollection.
+	 *
+	 * @see \Activitypub\Activity\Base_Object
+	 *
+	 * @return \Activitypub\Activity\Base_Object|\WP_Error The OrderedCollection or WP_Error on failure.
+	 */
+	public function to_object() {
+		$base_object               = new \Activitypub\Activity\Base_Object();
+		$base_object->{'@context'} = 'https://www.w3.org/ns/activitystreams';
+		$base_object->set_type( 'OrderedCollection' );
+		$base_object->set_id( \get_term_link( $this->item ) );
+
+		return $base_object;
+	}
+
+	/**
+	 * Get the OrderedCollection ID (term link).
+	 *
+	 * @return string The OrderedCollection ID (term link).
+	 */
+	public function to_id() {
+		return \get_term_link( $this->item );
+	}
+}

tests/phpunit/tests/includes/transformer/class-test-factory.php

@@ -13,6 +13,7 @@
 use Activitypub\Transformer\Factory;
 use Activitypub\Transformer\Json;
 use Activitypub\Transformer\Post;
+use Activitypub\Transformer\Term;
 
 /**
  * Test class for Transformer Factory.
@@ -48,6 +49,13 @@ class Test_Factory extends \WP_UnitTestCase {
 	 */
 	protected static $user_id;
 
+	/**
+	 * Test term ID.
+	 *
+	 * @var int
+	 */
+	protected static $term_id;
+
 	/**
 	 * Create fake data before tests run.
 	 *
@@ -80,6 +88,16 @@ public static function wpSetUpBeforeClass( $factory ) {
 				),
 			)
 		);
+
+		// Create test term.
+		$term          = $factory->term->create_and_get(
+			array(
+				'taxonomy' => 'post_tag',
+				'name'     => 'Test Tag',
+				'slug'     => 'test-tag',
+			)
+		);
+		self::$term_id = $term->term_id;
 	}
 
 	/**
@@ -266,4 +284,16 @@ public function test_get_transformer_with_wp_error() {
 		$this->assertEquals( 'test_error', $result->get_error_code() );
 		$this->assertEquals( 'Test error message', $result->get_error_message() );
 	}
+
+	/**
+	 * Test get_transformer with WP_Term.
+	 *
+	 * @covers ::get_transformer
+	 */
+	public function test_get_transformer_term() {
+		$term        = get_term( self::$term_id );
+		$transformer = Factory::get_transformer( $term );
+
+		$this->assertInstanceOf( Term::class, $transformer );
+	}
 }

tests/phpunit/tests/includes/transformer/class-test-term.php

@@ -0,0 +1,112 @@
+<?php
+/**
+ * Test file for Term Transformer.
+ *
+ * @package Activitypub
+ */
+
+namespace Activitypub\Tests\Transformer;
+
+use Activitypub\Transformer\Factory;
+use Activitypub\Transformer\Term;
+
+/**
+ * Test class for Term Transformer.
+ *
+ * @coversDefaultClass \Activitypub\Transformer\Term
+ */
+class Test_Term extends \WP_UnitTestCase {
+	/**
+	 * Test term ID.
+	 *
+	 * @var int
+	 */
+	protected static $term_id;
+
+	/**
+	 * Create fake data before tests run.
+	 *
+	 * @param \WP_UnitTest_Factory $factory Helper that creates fake data.
+	 */
+	public static function wpSetUpBeforeClass( $factory ) {
+		// Create a test tag.
+		$term          = $factory->term->create_and_get(
+			array(
+				'taxonomy' => 'post_tag',
+				'name'     => 'Test Term',
+				'slug'     => 'test-tag',
+			)
+		);
+		self::$term_id = $term->term_id;
+	}
+
+	/**
+	 * Test get_transformer with WP_Term.
+	 *
+	 * @covers \Activitypub\Transformer\Factory::get_transformer
+	 */
+	public function test_get_transformer_term() {
+		$term        = get_term( self::$term_id );
+		$transformer = Factory::get_transformer( $term );
+
+		$this->assertInstanceOf( Term::class, $transformer );
+	}
+
+	/**
+	 * Test to_object method.
+	 *
+	 * @covers ::to_object
+	 */
+	public function test_to_object() {
+		$term        = get_term( self::$term_id );
+		$transformer = new Term( $term );
+		$object      = $transformer->to_object();
+
+		// Should return a Base_Object.
+		$this->assertInstanceOf( \Activitypub\Activity\Base_Object::class, $object );
+
+		// Check ActivityStreams context.
+		$this->assertEquals( 'https://www.w3.org/ns/activitystreams', $object->{'@context'} );
+
+		// Check type is OrderedCollection.
+		$this->assertEquals( 'OrderedCollection', $object->get_type() );
+
+		// Check ID is the term link.
+		$expected_url = get_term_link( $term );
+		$this->assertEquals( $expected_url, $object->get_id() );
+	}
+
+	/**
+	 * Test to_id method.
+	 *
+	 * @covers ::to_id
+	 */
+	public function test_to_id() {
+		$term        = get_term( self::$term_id );
+		$transformer = new Term( $term );
+		$id          = $transformer->to_id();
+
+		// Should return the term link.
+		$expected_url = get_term_link( $term );
+		$this->assertEquals( $expected_url, $id );
+	}
+
+	/**
+	 * Test with category taxonomy.
+	 */
+	public function test_category_term() {
+		$category = self::factory()->term->create_and_get(
+			array(
+				'taxonomy' => 'category',
+				'name'     => 'Test Category',
+				'slug'     => 'test-category',
+			)
+		);
+
+		$transformer = new Term( $category );
+		$object      = $transformer->to_object();
+
+		$this->assertEquals( 'OrderedCollection', $object->get_type() );
+		$this->assertEquals( get_term_link( $category ), $object->get_id() );
+	}
+}