BEGIN {
   package Class;

   use strict;
   use warnings;

   use Moose;

   has val => (
      is       => 'rw',
      isa      => 'Num',
      required => 1,
   );


   use Moose::Util::TypeConstraints;

   coerce __PACKAGE__
      => from 'Num'
         => via { __PACKAGE__->new(val => $_) };
 }


BEGIN {
   package Container;

   use strict;
   use warnings;

   use Moose;

   has always => (
      is      => 'rw',
      isa     => 'Class',
      coerce  => 1,
      default => sub { Class->new(val => 0) },
   );

   has union => (
      is      => 'rw',
      isa     => 'Undef|Class',
      coerce  => 1,
      default => undef,
   );
}

use strict;
use warnings;

use Test::More tests => 30;

use Scalar::Util qw( blessed );

sub ta { $_[0] && blessed($_[0]->always) && blessed($_[0]->always) eq 'Class' }
sub tu { $_[0] && ( !$_[0]->union || blessed($_[0]->union) && blessed($_[0]->union) eq 'Class' ) }

my $always_fail = qr/^Attribute \(always\) does not pass the type constraint/;
my $union_fail  = qr/^Attribute \(union\) does not pass the type constraint/;

my $o = Class->new(val => 123);
my $c;

$c = eval { Container->new() };                 is($@, '');              ok(ta($c));
$c = eval { Container->new(always => $o) };     is($@, '');              ok(ta($c));
$c = eval { Container->new(always => 123) };    is($@, '');              ok(ta($c));
$c = eval { Container->new(always => "abc") };  like($@, $always_fail);  ok(!$c);

$c = eval { Container->new(union => undef) };   is($@, '');              ok(tu($c));
$c = eval { Container->new(union => $o) };      is($@, '');              ok(tu($c));
$c = eval { Container->new(union => 123) };     is($@, '');              ok(tu($c));
$c = eval { Container->new(union => "abc") };   like($@, $union_fail);   ok(!$c);

$c = Container->new();

eval { $c->always($o) };     is($@, '');              ok(tu($c));
eval { $c->always(123) };    is($@, '');              ok(tu($c));
eval { $c->always("abc") };  like($@, $always_fail);  ok(tu($c));

eval { $c->union(undef) };   is($@, '');              ok(tu($c));
eval { $c->union($o) };      is($@, '');              ok(tu($c));
eval { $c->union(123) };     is($@, '');              ok(tu($c));
eval { $c->union("abc") };   like($@, $union_fail);   ok(tu($c));