I knew that `[` was notionally the same as `test`, but had never 'checked'. I just assumed `[` was a built-in that conformed rather than them actually being the same.

So I very much enjoyed following along with the article, first seeing that `ls -il /bin/test` and `ls -il /bin/[` are at different inodes, then md5summing and seeing they are different, getting concerned, then the article revealing that is the case now (I'm trusting rather than verifying about the separate builds).

I was then very satisfied to recall that `[[` is a built-in (as `[[` isn't portable between all shells).