Add missing Utils file

libs/Matchmaking.Local/test/Matchmaking.Local.Test/Utils.cs

@@ -0,0 +1,85 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+
+using Microsoft.MixedReality.Sharing.Matchmaking;
+using System;
+using System.Collections.Generic;
+using System.Diagnostics;
+using System.Threading;
+using Xunit;
+
+namespace Matchmaking.Local.Test
+{
+    public static class Utils
+    {
+        public static int TestTimeoutMs
+        {
+            get
+            {
+                return Debugger.IsAttached ? Timeout.Infinite : 10000;
+            }
+        }
+
+        public static void AssertSameDictionary(IReadOnlyDictionary<string, string> a, IReadOnlyDictionary<string, string> b)
+        {
+            Assert.Equal(a.Count, b.Count);
+            foreach (var entry in a)
+            {
+                Assert.Equal(entry.Value, b[entry.Key]);
+            }
+        }
+
+        public class RaiiGuard : IDisposable
+        {
+            private Action Quit { get; set; }
+            public RaiiGuard(Action init, Action quit)
+            {
+                Quit = quit;
+                if (init != null) init();
+            }
+            void IDisposable.Dispose()
+            {
+                if (Quit != null) Quit();
+            }
+        }
+
+        // Run a query and wait for the predicate to be satisfied.
+        // Return the list of rooms which satisfied the predicate or null if canceled before the predicate was satisfied.
+        public static IEnumerable<IRoom> QueryAndWaitForRoomsPredicate(
+            IMatchmakingService svc, string type,
+            Func<IEnumerable<IRoom>, bool> pred, CancellationToken token)
+        {
+            using (var result = svc.StartDiscovery(type))
+            {
+                var rooms = result.Rooms;
+                bool predicateResult = pred(rooms);
+                if (predicateResult)
+                {
+                    return rooms; // optimistic path
+                }
+                using (var wakeUp = new AutoResetEvent(false))
+                {
+                    Action<IDiscoveryTask> onChange = (IDiscoveryTask sender) => wakeUp.Set();
+
+                    using (var unregisterCancel = token.Register(() => wakeUp.Set()))
+                    using (var unregisterWatch = new RaiiGuard(() => result.Updated += onChange, () => result.Updated -= onChange))
+                    {
+                        while (true)
+                        {
+                            rooms = result.Rooms;
+                            if (pred(rooms))
+                            {
+                                return rooms;
+                            }
+                            wakeUp.WaitOne(); // wait for cancel or update
+                            if (token.IsCancellationRequested)
+                            {
+                                return null;
+                            }
+                        }
+                    }
+                }
+            }
+        }
+    }
+}