Weighing: Add Gassner scale and update tests

Tests/WeighingTests/MockScale.cs

@@ -1,6 +1,7 @@
 using System.Net.Sockets;
 using System.Net;
 using System.Text;
+using System.IO;
 
 namespace Tests.WeighingTests {
     public abstract class MockScale : IDisposable {
@@ -63,9 +64,46 @@ namespace Tests.WeighingTests {
     }
 
     public class EventMockScale : MockScale {
+
+        private readonly Func<int, string?, int, (string, bool)> Handler;
+        private readonly Thread ServerThread;
+        private TcpClient? Client;
+        private bool IsRunning = true;
+
         public EventMockScale(int port, Func<int, string?, int, (string, bool)> handler) :
             base(port) {
-            // TODO
+            Handler = handler;
+            ServerThread = new Thread(new ParameterizedThreadStart(Serve));
+            ServerThread.Start();
+        }
+
+        private async void Serve(object? parameters) {
+            while (IsRunning) {
+                try {
+                    Client = await Server.AcceptTcpClientAsync();
+                } catch (Exception) {
+                    // ignore
+                }
+            }
+        }
+
+        public async Task Weigh(int weight) {
+            Weight = weight;
+            await Weigh();
+        }
+
+        public async Task Weigh() {
+            var (res, inc) = Handler(Weight, Error, IdentNr + 1);
+            if (inc) IdentNr++;
+            await Client!.GetStream().WriteAsync(Encoding.ASCII.GetBytes(res));
+        }
+
+        public new void Dispose() {
+            Client?.Dispose();
+            IsRunning = false;
+            ServerThread.Interrupt();
+            ServerThread.Join();
+            base.Dispose();
         }
     }
 }