The benefit for two checks is that each rule can be tuned separately. You might realize there are a number of weird endings that you don't like, such as m{ [#@$.~] $ }x.

The negative aspect of using two regex to check legality is that it's a bit harder to supply a rule in a configuration file, such as those used by spam filters, etc. If your code can't handle two supplied regex, then you'll have to figure out one.

A negative look-behind is useful.

print if m{
            ^                 # begins with
            test              # 'test'
            \d+               # a number
            .*?               # nothing or anything else
            (?<! ~ )          # but no '~' at the tail
            $                 # to the end
          }ix;
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