vars_ok does not find lexicals that aren't in a sub

[petdance]

Here's my lib/foo.pm

package foo;

my $scalar;
my %hash;
my @array;

1;

and here's my foo.t

#!/usr/bin/perl

use warnings;
use strict;
use 5.010;
use experimental 'signatures';

use Test::More tests => 1;

use Test::Vars;

vars_ok( 'lib/foo.pm' );

exit 0;

When I run the test, the test passes, although there are three unused vars in lib/foo.pm.