--- /dev/null
+use strict;
+use warnings;
+use Test::More tests => 4;
+{
+ package Response;
+ use Mouse;
+ use Mouse::Util::TypeConstraints;
+
+ require t::lib::ClassType_Foo;
+
+ # XXX: This below API is different from that of Moose.
+ # class_type() should be class_type 'ClassName';
+ # class_type 'Headers' => { class => 't::lib::ClassType_Foo' };
+ # this should be subtype Headers => as 't::lib::ClassType_foo';
+ subtype 'Headers'
+ => as 't::lib::ClassType_Foo'
+ ;
+
+ coerce 'Headers' =>
+ from 'HashRef' => via {
+ t::lib::ClassType_Foo->new(%{ $_ });
+ },
+ ;
+
+ has headers => (
+ is => 'rw',
+ isa => 'Headers',
+ coerce => 1,
+ );
+}
+
+my $res = Response->new(headers => { foo => 'bar' });
+isa_ok($res->headers, 't::lib::ClassType_Foo');
+is($res->headers->foo, 'bar');
+$res->headers({foo => 'yay'});
+isa_ok($res->headers, 't::lib::ClassType_Foo');
+is($res->headers->foo, 'yay');