tests: Implement multi-monitor tests using Xdmx

testcases/t/500-multi-monitor.t

@@ -0,0 +1,21 @@
+#!perl
+# vim:ts=4:sw=4:expandtab
+#
+# Tests that the provided X-Server to the t/5??-*.t tests is actually providing
+# multiple monitors.
+#
+use i3test;
+
+my $i3 = i3(get_socket_path());
+
+####################
+# Request tree
+####################
+
+my $tree = $i3->get_tree->recv;
+
+my @outputs = map { $_->{name} } @{$tree->{nodes}};
+is_deeply(\@outputs, [ '__i3', 'xinerama-0', 'xinerama-1' ],
+          'multi-monitor outputs ok');
+
+done_testing;