`[[ -n $VAR ]]` equal to `[[ $VAR ]]`?

[Thorsten Kampe <thorsten@xxxxxxxxxxxxxxxx>]

Hi,

this is kind of a follow-up to 
http://www.zsh.org/mla/users/2011/msg00284.html .

Basically the solutions were `((+VAR))` for zsh and `[[ -n 
${VAR+stuff} ]]` for bash and zsh.

Now my question is, isn't `[[ -n $VAR ]]` equivalent to `[[ $VAR ]]`? 
(`[[ -n ${VAR+stuff} ]]` equivalent to `[[ ${VAR+stuff} ]]`)

Thorsten