What do you consider a "valid date"?

Maybe try writing down what the program should do and what rules it should enforce. Then take those rules and write them in Perl code.

For a start, the following program provides a framework for you:

#!perl
use strict;
use warnings;
use Test::More tests => 'no_plan';

sub verify_date {
    my( $date ) = @_;
};

my @testcases = (
    [ '01-01-70', 1 ], # ok
    [ '01-12-70', 1 ], # ok
    [ '12-01-70', 1 ], # ok
    [ '12-01-12', 1 ], # ok
    [ '12-12-01', 1 ], # ok
    [ '70-01-01', 0 ], # not ok
    [ '02-30-70', 0 ], # not ok
    [ '02-02-1970', 0 ], # not ok
    [ 'ab-02-1970', 0 ], # not ok
);

for my $testcase ( @testcases ) {
    my( $value, $expected ) = @$testcase;
    is verify_date( $value ), $expected, $value;
};

done_testing;
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