SC2236 and SC2237 are not issued for `test`

[e-kwsm]

For bugs

• Rule Id (if any, e.g. SC1000): SC2236 and SC2237
• My shellcheck version (shellcheck --version or 'online'): online
• I tried on shellcheck.net and verified that this is still a problem on the latest commit
• It's not reproducible on shellcheck.net, but I think that's because it's an OS, configuration or encoding issue

For new checks and feature suggestions

• shellcheck.net (i.e. the latest commit) currently gives no useful warnings about this
• I searched through https://github.com/koalaman/shellcheck/issues and didn't find anything related

Here's a snippet or screenshot that shows the problem:

#!/bin/sh
test ! -n "$1"
! test -z "$1"

Here's what shellcheck currently says:

nothing

Here's what I wanted or expected to see:

Line 2	SC2236: Use -z instead of ! -n.
Line 3	SC2237: Use test -n .. instead of ! test -z ...