Perl6 Alias trait

Tests

[cjfields@Chriss-MacBook-Pro bioperl6 (master)]$ prove6 -l -v t/Role/Aliased.t
t/Role/Aliased.t ..
ok 1 -
not ok 2 - adds alias

# Failed test 'adds alias'
# at t/Role/Aliased.t line 23
ok 3 -
1..3
# Looks like you failed 1 tests of 3
Dubious, test returned 1 (wstat 256, 0x100)
Failed 1/3 subtests

Test Summary Report
-------------------
t/Role/Aliased.t (Wstat: 256 Tests: 3 Failed: 1)
  Failed test:  2
  Non-zero exit status: 1
Files=1, Tests=3,  0 wallclock secs ( 0.02 usr  0.01 sys +  0.31 cusr  0.05 csys =  0.39 CPU)
Result: FAIL

trait test code

use v6;

use Test;

multi trait_mod:<is>(Attribute:D $attr, :$alias!) {
    my $accessor_name = $attr.name.substr(2);
    
    for $alias.list -> $name {
        $attr.HOW.add_method($attr.HOW, $name, method {
            self.$accessor_name
        } );
    }
}

class Stub {
    has $.a is alias('foo');
    has $.long_name is alias('bar');
};

my $test = Stub.new(:a<hi there>, :long_name<Long time no see>);

is($test.a, 'hi there', '');
ok($test.can('foo'), 'adds alias');

# Does not work, get "No such method 'foo' for invocant of type 'Stub'"
#is($test.foo, 'hi there');

is($test.long_name, 'Long time no see');

done();