+# Test 1-2: Sending a duplicate extension should fail.
+$proxy->start() or plan skip_all => "Unable to start up Proxy for tests";
+plan tests => 7;
+ok(TLSProxy::Message->fail(), "Duplicate ClientHello extension");
+
+$proxy->clear();
+$proxy->filter(\&inject_duplicate_extension_serverhello);
+$proxy->start();
+ok(TLSProxy::Message->fail(), "Duplicate ServerHello extension");
+