How to iterate over array indices in zsh?

In bash we can iterate over index of an array like this

~$ for i in "${!test[@]}"; do echo $i; done

where test is an array, say,

~$ test=(a "b c d" e f)

so that the output looks like

0
1
2
3

However, when I do the same in zsh I get an error:

➜ ~ for i in "${!test[@]}"; do echo $i; done
zsh: event not found: test[@]

What is going on? What is the proper way of iterating over indices in zsh?