WP_Site_Health::test_php_extension_availability( string $extension_name = null, string $function_name = null, string $constant_name = null, string $class_name = null ): bool

844	private function test_php_extension_availability( $extension_name = null, $function_name = null, $constant_name = null, $class_name = null ) {845		// If no extension or function is passed, claim to fail testing, as we have nothing to test against.846		if ( ! $extension_name && ! $function_name && ! $constant_name && ! $class_name ) {847			return false;848		}849 850		if ( $extension_name && ! extension_loaded( $extension_name ) ) {851			return false;852		}853 854		if ( $function_name && ! function_exists( $function_name ) ) {855			return false;856		}857 858		if ( $constant_name && ! defined( $constant_name ) ) {859			return false;860		}861 862		if ( $class_name && ! class_exists( $class_name ) ) {863			return false;864		}865 866		return true;867	}