+is($@, '', 'callback returning undef doesn\'t warn/croak');
+is($x, $n, 'callback returning undef fails');
+
+my @callers;
+$wiz = wizard get => sub {
+ my @c;
+ my $i = 0;
+ while (@c = caller $i++) {
+ push @callers, [ @c[0, 1, 2] ];
+ }
+};
+
+my $b;
+cast $b, $wiz;
+
+my $u = $b;
+is_deeply(\@callers, [
+ [ 'main', $0, __LINE__-2 ],
+], 'caller into callback returns the right thing');
+
+@callers = ();
+$u = $b;
+is_deeply(\@callers, [
+ [ 'main', $0, __LINE__-2 ],
+], 'caller into callback returns the right thing (second time)');
+
+{
+ @callers = ();
+ my $u = $b;
+ is_deeply(\@callers, [
+ [ 'main', $0, __LINE__-2 ],
+ ], 'caller into callback into block returns the right thing');
+}
+
+@callers = ();
+eval { my $u = $b };
+is($@, '', 'caller into callback doesn\'t croak');
+is_deeply(\@callers, [
+ ([ 'main', $0, __LINE__-3 ]) x 2,
+], 'caller into callback into eval returns the right thing');