✅ write some failing tests

prototypes/quic_demo/README.md

@@ -1,4 +1,4 @@
-# Testing
+# End-to-end Testing
 
 There are 5 processes, so you'll need 5 terminal windows or screen / tmux
 sessions. Run the processes in this order:
@@ -11,6 +11,15 @@ sessions. Run the processes in this order:
 
 The netcat processes from steps 1 and 5 should now be connected to each other.
 
+# Testing PTTH itself
+
+The end-to-end testing above is the happy path. Try these sadder cases:
+
+- After Step 2, restart the server proxy P4
+- After Step 3, restart the client proxy P2
+- After Step 2, restart the relay server P3
+- After Step 3, restart the relay server P3
+
 # Plan
 
 This is a TCP port forwarding system, like SSH has, but better.