Add WithMessageBus to ReactiveUI.Testing

Author: anaisbetts

ReactiveUI.Testing/TestUtils.cs

@@ -90,7 +90,37 @@ public static void With(this TestScheduler sched, Action<TestScheduler> block)
             sched.With(x => { block(x); return 0; });
         }
 
+        /// <summary>
+        /// WithMessageBus allows you to override the default Message Bus 
+        /// implementation until the object returned is disposed. If a 
+        /// message bus is not specified, a default empty one is created.
+        /// </summary>
+        /// <param name="messageBus">The message bus to use, or null to create
+        /// a new one using the default implementation.</param>
+        /// <returns>An object that when disposed, restores the original 
+        /// message bus.</returns>
+        public static IDisposable WithMessageBus(this TestScheduler sched, IMessageBus messageBus = null)
+        {
+            var origMessageBus = RxApp.MessageBus;
+
+            RxApp.MessageBus = messageBus ?? new MessageBus();
+            return Disposable.Create(() => RxApp.MessageBus = origMessageBus);
+        }
 
+        /// <summary>
+        /// WithMessageBus allows you to override the default Message Bus 
+        /// implementation for a specified action. If a message bus is not
+        /// specified, a default empty one is created.
+        /// <param name="block">The action to execute.</param>
+        /// <param name="messageBus">The message bus to use, or null to create
+        /// a new one using the default implementation.</param>
+        public static void WithMessageBus(this TestScheduler sched, Action<IMessageBus> block, IMessageBus messageBus = null)
+        {
+            messageBus = messageBus ?? new MessageBus();
+            using(var _ = sched.WithMessageBus(messageBus)) {
+                block(messageBus);
+            }
+        }
 
         /// <summary>
         /// RunToMilliseconds moves the TestScheduler to the specified time in

ReactiveUI/RxApp.cs

@@ -140,11 +140,25 @@ public static IScheduler TaskpoolScheduler {
         /// </summary>
         public static Func<string, ILog> LoggerFactory { get; set; }
 
+
+        [ThreadStatic] static IMessageBus _UnitTestMessageBus;
+        static IMessageBus _MessageBus;
+
         /// <summary>
         /// Set this property to implement a custom MessageBus for
         /// MessageBus.Current.
         /// </summary>
-        public static IMessageBus MessageBus { get; set; }
+        public static IMessageBus MessageBus {
+            get { return _UnitTestMessageBus ?? _MessageBus; }
+            set {
+                if (InUnitTestRunner()) {
+                    _UnitTestMessageBus = value;
+                    _MessageBus = _MessageBus ?? value;
+                } else {
+                    _MessageBus = value;
+                }
+            }
+        }
 
 #if FALSE
         public static Func<UserException, RecoveryOptionResult> CustomErrorPresentationFunc { get; set; }