print_r

<?php             is_array($value) => '[]',

            is_object($value) => get_class($value),

            is_string($value) => $value,

            default => print_r($value, true),

        };

    }

}

<?php             sprintf(

                'Event [%s] does not have the [%s] listener attached to it',

                $expectedEvent,

                print_r($expectedListener, true)

            )

        );

    }