... and it doesn't work as expected (example codebase). I get the error State(NotTurnToWrite) at the noise.write_message call.

now it fails with Decrypt error at noise.read_message call...
currently, all fatal errors seem to happen on server/responder side.
I use the XK pattern, in the following, I marked everything that succeeds with * (every error with !) + r for "read ok" and w for "write ok", after | I write the simulated size.

XK:
<- s
...
-> e, es   *w *r | 48
<- e, ee   *w *r | 48
-> s, se   *w !r | 64

e.g. only the last read fails, and I don't know why. Also, the last message is bigger than the rest...

Another possibility to solve this w/o this solution, would be to introduce some simulate_read_message method, similiar to the here-introduced simulate_write_message, but which should report which input size it does expect, so that input can be truncated.

I'm pretty sure that some state change isn't catched by the simulate_write_message method.