Improves the init_func_params for overriding the bookmark.

tests/phpunit/tests/bookmark/getBookmark.php

@@ -152,23 +152,30 @@ public function data_when_instance_bookmark() {
 	}
 
 	/**
-	 * Initializes the get_bookmark's function parameters to match the order of the function's signature and
+	 * Initialize the get_bookmark's function parameters to match the order of the function's signature and
 	 * reduce code in the tests.
 	 *
 	 * @param array        $params   Array of given function parameters.
 	 * @param int|stdClass $bookmark Optional. Bookmark's cache key or instance.
 	 *
-	 * @return array An array of ordered parameter.
+	 * @return array An array of ordered parameters.
 	 */
 	private function init_func_params( array $params, $bookmark = null ) {
-		$defaults           = array(
-			'bookmark' => 0,
+		// The defaults sets the order to match the function's parameters as well as setting the default values.
+		$defaults = array(
+			'bookmark' => self::$bookmark,
 			'output'   => OBJECT,
 			'filter'   => 'raw',
 		);
-		$params             = array_merge( $defaults, $params );
-		$params['bookmark'] = is_null( $bookmark ) ? self::$bookmark : $bookmark;
+		$params   = array_merge( $defaults, $params );
 
+		// When given a bookmark, use it.
+		if ( ! is_null( $bookmark ) ) {
+			$params['bookmark'] = $bookmark;
+		}
+
+		// Strip out the keys. Why? The splat operator (...) does not work with associative arrays,
+		// except for in PHP 8 where the keys are named arguments.
 		return array_values( $params );
 	}