add failing toString tests
add failing toString tests

btd/buffer,beni55/buffer,LiuDeng/buffer,loon3/buffer,SAGV/buffer,LiuDeng/buffer,SAGV/buffer,feross/buffer,feross/buffer,LinusU/buffer,feross/buffer,btd/buffer,nolanlawson/buffer,loon3/buffer,LinusU/buffer,beni55/buffer,nolanlawson/buffer