--- /dev/null
+#!/usr/bin/perl -w
+
+# tree.t
+
+use Devel::Symdump;
+
+package Coffee;
+@ISA = qw(Liquid Black);
+
+package Liquid;
+package Black;
+
+package Martini;
+@ISA = qw(Liquid);
+
+package Martini::White;
+@ISA = qw(Martini);
+package Martini::Red;
+@ISA = qw(Martini);
+
+print "1..2\n";
+my @s = split /\n/, Devel::Symdump->isa_tree;
+print @s >= 11 ? "ok 1\n" : "not ok [@s]\n";
+@s = split /\n/, Devel::Symdump->inh_tree;
+print @s >= 9 ? "ok 2\n" : "not ok [@s]\n";
+
+# The tests are testing with the > operator, because we never know where
+# Exporter and Carp (and others) are developing into.