Testing for valid package names

[boftx]

I have a need to test a string to see if it would be a valid name for a package suitable for submission to CPAN. Currently, I am taking a rather draconic approach and allowing only the characters that are matched by \w.

My questions are these:

1. Is my character set too restrictive, or is it reasonable in light of the majority of use-cases and portability concerns?
2. Should I remove the "_" character from the list?
3. What improvements can be made to the test cases below to better test edge cases?

Here is the test code:

#!/usr/bin/perl -T

use 5.008_008;

use strict;
use warnings FATAL => 'all';

use Test::More;

my @good_pnames = (
    qw(
      foo
      foo::bar
      foo_bar
      foo::bar_baz
      )
);

my @bad_pnames = (
    qw(
      foo.pm
      foo!
      foo:
      foo::
      foo::!
      foo:bar
      foo::bar!
      foo::bar:baz
      )
);
push( @bad_pnames, 'foo bar' );

for (@good_pnames) {
    ok( valid_pname($_), "$_ is valid" );
}

for (@bad_pnames) {
    ok( !valid_pname($_), "$_ is not valid" )
      or BAIL_OUT("Invalid package was accepted! $_");
}

done_testing();

exit;

sub valid_pname {
    my $pname = shift;

    return !!($pname =~ /^\w+(?:::\w+)*$/);
}

__END__

Update: Added foo.pm to list of bad names.

Update 2: Questions 1 and 2 are answered directly by the code from Module::Runtime supplied below by tobyink