Bash completion

Assuming you already have Homebrew installed

brew install bash-completion

Add the following lines to your ~/.bash_profile:

if [ -f $(brew --prefix)/etc/bash_completion ]; then
        . $(brew --prefix)/etc/bash_completion
fi

Install the ZFS bash completions:

cd /usr/local/etc/bash_completion.d
curl -O https://raw.githubusercontent.com/zfsonlinux/zfs/master/contrib/bash_completion.d/zfs

Open a new terminal window.