If you want to catch this sort of thing, you could try using Perl::Critic. For example, running the default perlcritic command on your example code:

use strict;
open FH, ">test.txt" or die "not able to open file for writing $!";
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produces three warnings, as shown below:

# perlcritic blah.pl
Bareword file handle opened at line 2, column 1.  See pages 202,204 of
+ PBP.  (Severity: 5)
Two-argument "open" used at line 2, column 1.  See page 207 of PBP.  (
+Severity: 5)
Code before warnings are enabled at line 2, column 1.  See page 431 of
+ PBP.  (Severity: 5)
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