--- /dev/null
+#!/usr/bin/perl
+
+use strict;
+use warnings;
+
+use Test::More tests => 11;
+use Test::Exception;
+
+BEGIN {
+ use_ok('Mouse::Util::TypeConstraints');
+}
+
+# subtype 'aliasing' ...
+
+lives_ok {
+ subtype 'Numb3rs' => as 'Num';
+} '... create bare subtype fine';
+
+my $numb3rs = find_type_constraint('Numb3rs');
+isa_ok($numb3rs, 'Mouse::Meta::TypeConstraint');
+
+# subtype with unions
+
+{
+ package Test::Mouse::Meta::TypeConstraint::Union;
+
+ use overload '""' => sub {'Broken|Test'}, fallback => 1;
+ use Mouse;
+
+ extends 'Mouse::Meta::TypeConstraint';
+}
+
+my $dummy_instance = Test::Mouse::Meta::TypeConstraint::Union->new;
+
+ok $dummy_instance => "Created Instance";
+
+isa_ok $dummy_instance,
+ 'Test::Mouse::Meta::TypeConstraint::Union' => 'isa correct type';
+
+is "$dummy_instance", "Broken|Test" =>
+ 'Got expected stringification result';
+
+my $subtype1 = subtype 'New1' => as $dummy_instance;
+
+ok $subtype1 => 'made a subtype from our type object';
+
+my $subtype2 = subtype 'New2' => as $subtype1;
+
+ok $subtype2 => 'made a subtype of our subtype';
+
+# assert_valid
+
+{
+ my $type = find_type_constraint('Num');
+
+ my $ok_1 = eval { $type->assert_valid(1); };
+ ok($ok_1, "we can assert_valid that 1 is of type $type");
+
+ my $ok_2 = eval { $type->assert_valid('foo'); };
+ my $error = $@;
+ ok(! $ok_2, "'foo' is not of type $type");
+ like(
+ $error,
+ qr{validation failed for .\Q$type\E.}i,
+ "correct error thrown"
+ );
+}