Add tests for `multi` command without block given.
Add tests for `multi` command without block given.

guilleiguaran/fakeredis,hoffmanc/fakeredis,TiteiKo/fakeredis,carsonreinke/fakeredis,zegal-cn/fakeredis,meetupcall/fakeredis,alienxp03/fakeredis,alexlag/fakeredis,caulfield/fakeredis