Also, you can get more help from B::Lint

perl -MO=Lint code.pl
Nonexistant subroutine 'Test::scaler' called at code.pl
z syntax OK
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and perlcritic

perlcritic -1 code.pl
Subroutine "scaler" is neither declared nor explicitly imported at lin
+e 12, column 9.  This might be a major bug.  (Severity: 4)
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