--- /dev/null
+#!/usr/bin/perl
+
+use strict;
+use warnings;
+
+use Test::More tests => 9;
+use Test::Exception;
+
+BEGIN {
+ use_ok('Mouse::Util::TypeConstraints');
+}
+
+my $r = Mouse::Util::TypeConstraints->get_type_constraint_registry;
+
+# Array of Ints
+
+my $array_of_ints = Mouse::Meta::TypeConstraint::Parameterized->new(
+ name => 'ArrayRef[Int]',
+ parent => find_type_constraint('ArrayRef'),
+ type_parameter => find_type_constraint('Int'),
+);
+isa_ok($array_of_ints, 'Mouse::Meta::TypeConstraint::Parameterized');
+isa_ok($array_of_ints, 'Mouse::Meta::TypeConstraint');
+
+$r->add_type_constraint($array_of_ints);
+
+is(find_type_constraint('ArrayRef[Int]'), $array_of_ints, '... found the type we just added');
+
+# Hash of Ints
+
+my $hash_of_ints = Mouse::Meta::TypeConstraint::Parameterized->new(
+ name => 'HashRef[Int]',
+ parent => find_type_constraint('HashRef'),
+ type_parameter => find_type_constraint('Int'),
+);
+isa_ok($hash_of_ints, 'Mouse::Meta::TypeConstraint::Parameterized');
+isa_ok($hash_of_ints, 'Mouse::Meta::TypeConstraint');
+
+$r->add_type_constraint($hash_of_ints);
+
+is(find_type_constraint('HashRef[Int]'), $hash_of_ints, '... found the type we just added');
+
+## now attempt a coercion
+
+{
+ package Foo;
+ use Mouse;
+ use Mouse::Util::TypeConstraints;
+
+ coerce 'ArrayRef[Int]'
+ => from 'HashRef[Int]'
+ => via { [ values %$_ ] };
+
+ has 'bar' => (
+ is => 'ro',
+ isa => 'ArrayRef[Int]',
+ coerce => 1,
+ );
+
+}
+
+my $foo = Foo->new(bar => { one => 1, two => 2, three => 3 });
+isa_ok($foo, 'Foo');
+
+is_deeply([ sort @{$foo->bar} ], [ 1, 2, 3 ], '... our coercion worked!');
+
+