The code below might be what you need to see if a module is installed.

use ExtUtils::Installed;

my $inst = ExtUtils::Installed->new();
my @missing = $inst->validate("File::BaseName");
print @missing;
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In this case, the @missing array shows:

File::BaseName is not installed...
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The validate method returns a list of the missing files. Some of the other methods could help, too.