/wp/v2/pattern-directory/patterns endpoint: slug parameter has no effect on the response

src/wp-includes/rest-api/endpoints/class-wp-rest-pattern-directory-controller.php

@@ -119,16 +119,7 @@ public function get_items( $request ) {
 			$query_args['slug'] = $slug;
 		}
 
-		/*
-		 * Include a hash of the query args, so that different requests are stored in
-		 * separate caches.
-		 *
-		 * MD5 is chosen for its speed, low-collision rate, universal availability, and to stay
-		 * under the character limit for `_site_transient_timeout_{...}` keys.
-		 *
-		 * @link https://stackoverflow.com/questions/3665247/fastest-hash-for-non-cryptographic-uses
-		 */
-		$transient_key = 'wp_remote_block_patterns_' . md5( implode( '-', $query_args ) );
+		$transient_key = $this->get_transient_key( $query_args );
 
 		/*
 		 * Use network-wide transient to improve performance. The locale is the only site
@@ -337,6 +328,11 @@ public function get_collection_params() {
 			'minimum'     => 1,
 		);
 
+		$query_params['slug'] = array(
+			'description' => __( 'Limit results to those matching a pattern (slug).' ),
+			'type'        => 'array',
+		);
+
 		/**
 		 * Filter collection parameters for the block pattern directory controller.
 		 *
@@ -346,4 +342,39 @@ public function get_collection_params() {
 		 */
 		return apply_filters( 'rest_pattern_directory_collection_params', $query_params );
 	}
+
+	/*
+	 * Include a hash of the query args, so that different requests are stored in
+	 * separate caches.
+	 *
+	 * MD5 is chosen for its speed, low-collision rate, universal availability, and to stay
+	 * under the character limit for `_site_transient_timeout_{...}` keys.
+	 *
+	 * @link https://stackoverflow.com/questions/3665247/fastest-hash-for-non-cryptographic-uses
+	 *
+	 * @since 6.0.0
+	 *
+	 * @param array $query_args Query arguments to generate a transient key from.
+	 *
+	 * @return string Transient key.
+	 */
+	protected function get_transient_key( $query_args ) {
+
+		if ( isset( $query_args['slug'] ) ) {
+			// This is an additional precaution because the "sort" function expects an array.
+			$query_args['slug'] = (array) $query_args['slug'];
+
+			// Sort the array so that the transient key doesn't depend on the order of slugs.
+			sort( $query_args['slug'] );
+
+			// Slugs have to be imploded separately as implode doesn't work with recursive arrays.
+			$query_args['slug'] = implode( ',', $query_args['slug'] );
+
+			if ( '' === trim( $query_args['slug'] ) ) {
+				unset( $query_args['slug'] );
+			}
+		}
+
+		return 'wp_remote_block_patterns_' . md5( implode( '-', $query_args ) );
+	}
 }

tests/phpunit/tests/rest-api/rest-pattern-directory-controller.php

@@ -21,6 +21,15 @@ class WP_REST_Pattern_Directory_Controller_Test extends WP_Test_REST_Controller_
 	 */
 	protected static $contributor_id;
 
+	/**
+	 * An instance of WP_REST_Pattern_Directory_Controller class.
+	 *
+	 * @since 6.0.0
+	 *
+	 * @var WP_REST_Pattern_Directory_Controller
+	 */
+	private static $controller;
+
 	/**
 	 * Set up class test fixtures.
 	 *
@@ -34,6 +43,8 @@ public static function wpSetUpBeforeClass( $factory ) {
 				'role' => 'contributor',
 			)
 		);
+
+		static::$controller = new WP_REST_Pattern_Directory_Controller();
 	}
 
 	/**
@@ -399,6 +410,85 @@ public function test_get_item_schema() {
 		$this->markTestSkipped( "The controller's schema is hardcoded, so tests would not be meaningful." );
 	}
 
+	/**
+	 * Tests if the transient key gets generated correctly.
+	 *
+	 * @dataProvider data_get_query_parameters
+	 *
+	 * @covers WP_REST_Pattern_Directory_Controller::get_transient_key
+	 *
+	 * @since 6.0.0
+	 *
+	 * @ticket 55617
+	 *
+	 * @param array     $parameters_1   Expected query arguments.
+	 * @param array     $parameters_2   Actual query arguments.
+	 * @param string    $message        An error message to display.
+	 * @param bool      $assert_same    Assertion type (assertSame vs assertNotSame).
+	 */
+	public function test_transient_keys_get_generated_correctly( $parameters_1, $parameters_2, $message, $assert_same = true ) {
+		$method = $this->get_reflection_method( self::$controller, 'get_transient_key' );
+
+		$result_1 = $method->invoke( self::$controller, $parameters_1 );
+		$result_2 = $method->invoke( self::$controller, $parameters_2 );
+
+		$this->assertIsString( $result_1 );
+		$this->assertNotEmpty( $result_1 );
+
+		$this->assertIsString( $result_2 );
+		$this->assertNotEmpty( $result_2 );
+
+		if ( $assert_same ) {
+			$this->assertSame( $result_1, $result_2, $message );
+		} else {
+			$this->assertNotSame( $result_1, $result_2, $message );
+		}
+
+	}
+
+	/**
+	 * @since 6.0.0
+	 *
+	 * @ticket 55617
+	 */
+	public function data_get_query_parameters() {
+		return array(
+			array(
+				array(
+					'parameter_1' => 1,
+					'slug'        => array(),
+				),
+				array(
+					'parameter_1' => 1,
+				),
+				'Empty slugs should not affect the transient key.',
+			),
+			array(
+				array(
+					'parameter_1' => 1,
+					'slug'        => array( 0, 2 ),
+				),
+				array(
+					'parameter_1' => 1,
+					'slug'        => array( 2, 0 ),
+				),
+				'message' => 'The order of slugs should not affect transient key.',
+			),
+			array(
+				array(
+					'parameter_1' => 1,
+					'slug'        => array( 'some_slug' ),
+				),
+				array(
+					'parameter_1' => 1,
+					'slug'        => array( 'some_other_slug' ),
+				),
+				'message' => 'Transient keys must not match.',
+				false,
+			),
+		);
+	}
+
 	/**
 	 * Simulate a successful outbound HTTP requests, to keep tests pure and performant.
 	 *
@@ -461,4 +551,21 @@ static function ( $return, $args, $url ) use ( $blocked_host ) {
 			3
 		);
 	}
+
+	/**
+	 * Returns a reflection method and changes its scope.
+	 *
+	 * @since 6.0.0
+	 *
+	 * @param $object An object that has a private method that has to be called.
+	 * @param $method Name of the method.
+	 *
+	 * @return ReflectionMethod
+	 */
+	private function get_reflection_method( $object, $method ) {
+		$reflection_method = new ReflectionMethod( $object, $method );
+		$reflection_method->setAccessible( true );
+
+		return $reflection_method;
+	}
 }

tests/qunit/fixtures/wp-api-generated.js

@@ -10385,6 +10385,11 @@ mockedApiResponse.Schema = {
                             "type": "integer",
                             "minimum": 1,
                             "required": false
+                        },
+                        "slug": {
+                            "description": "Limit results to those matching a pattern (slug).",
+                            "type": "array",
+                            "required": false
                         }
                     }
                 }