First version of asynchronix based mini simulator

- Basic simulator with 3 devices
- Can be driven via a UDP interface
- Design allows to drive the simulation via different interface in the future
  by using Request/Reply messaging.

satrs-minisim/src/test_helpers.rs

@@ -0,0 +1,56 @@
+use delegate::delegate;
+use std::{sync::mpsc, time::Duration};
+
+use asynchronix::time::MonotonicTime;
+use satrs_minisim::{SimReply, SimRequest};
+
+use crate::{controller::SimController, create_sim_controller, ThreadingModel};
+
+pub struct SimTestbench {
+    pub sim_controller: SimController,
+    pub reply_receiver: mpsc::Receiver<SimReply>,
+    pub request_sender: mpsc::Sender<SimRequest>,
+}
+
+impl SimTestbench {
+    pub fn new() -> Self {
+        let (request_sender, request_receiver) = mpsc::channel();
+        let (reply_sender, reply_receiver) = mpsc::channel();
+        let t0 = MonotonicTime::EPOCH;
+        let sim_ctrl =
+            create_sim_controller(ThreadingModel::Single, t0, reply_sender, request_receiver);
+
+        Self {
+            sim_controller: sim_ctrl,
+            reply_receiver,
+            request_sender,
+        }
+    }
+
+    delegate! {
+        to self.sim_controller {
+            pub fn handle_sim_requests(&mut self);
+        }
+        to self.sim_controller.simulation {
+            pub fn step(&mut self);
+            pub fn step_by(&mut self, duration: Duration);
+        }
+    }
+
+    pub fn send_request(&self, request: SimRequest) -> Result<(), mpsc::SendError<SimRequest>> {
+        self.request_sender.send(request)
+    }
+
+    pub fn try_receive_next_reply(&self) -> Option<SimReply> {
+        match self.reply_receiver.try_recv() {
+            Ok(reply) => Some(reply),
+            Err(e) => {
+                if e == mpsc::TryRecvError::Empty {
+                    None
+                } else {
+                    panic!("reply_receiver disconnected");
+                }
+            }
+        }
+    }
+}