Add Execute.PostToUIThreadAsync

Stylet/Execute.cs

@@ -84,6 +84,7 @@ namespace Stylet
         /// <summary>
         /// Dispatches the given action to be run on the UI thread asynchronously, even if the current thread is the UI thread
         /// </summary>
+        /// <param name="action">Action to run on the UI thread</param>
         public static void PostToUIThread(Action action)
         {
             EnsureDispatcher();
@@ -93,9 +94,29 @@ namespace Stylet
                 action();
         }
 
+        /// <summary>
+        /// Dispatches the given action to be run on the UI thread asynchronously, and returns a task which completes when the action completes, even if the current thread is the UI thread
+        /// </summary>
+        /// <param name="action">Action to run on the UI thread</param>
+        /// <returns>Task which completes when the action has been run</returns>
+        public static Task PostToUIThreadAsync(Action action)
+        {
+            EnsureDispatcher();
+            if (!TestExecuteSynchronously)
+            {
+                return PostOnUIThreadInternalAsync(action);
+            }
+            else
+            {
+                action();
+                return Task.FromResult(false);
+            }
+        }
+
         /// <summary>
         /// Dispatches the given action to be run on the UI thread asynchronously, or runs it synchronously if the current thread is the UI thread
         /// </summary>
+        /// <param name="action">Action to run on the UI thread</param>
         public static void OnUIThread(Action action)
         {
             EnsureDispatcher();
@@ -108,6 +129,7 @@ namespace Stylet
         /// <summary>
         /// Dispatches the given action to be run on the UI thread and blocks until it completes, or runs it synchronously if the current thread is the UI thread
         /// </summary>
+        /// <param name="action">Action to run on the UI thread</param>
         public static void OnUIThreadSync(Action action)
         {
             EnsureDispatcher();
@@ -138,25 +160,14 @@ namespace Stylet
         /// <summary>
         /// Dispatches the given action to be run on the UI thread and returns a task that completes when the action completes, or runs it synchronously if the current thread is the UI thread
         /// </summary>
+        /// <param name="action">Action to run on the UI thread</param>
+        /// <returns>Task which completes when the action has been run</returns>
         public static Task OnUIThreadAsync(Action action)
         {
             EnsureDispatcher();
             if (!TestExecuteSynchronously && !Dispatcher.IsCurrent)
             {
-                var tcs = new TaskCompletionSource<object>();
-                Dispatcher.Post(() =>
-                {
-                    try
-                    {
-                        action();
-                        tcs.SetResult(null);
-                    }
-                    catch (Exception e)
-                    {
-                        tcs.SetException(e);
-                    }
-                });
-                return tcs.Task;
+                return PostOnUIThreadInternalAsync(action);
             }
             else
             {
@@ -165,6 +176,24 @@ namespace Stylet
             }
         }
 
+        private static Task PostOnUIThreadInternalAsync(Action action)
+        {
+            var tcs = new TaskCompletionSource<object>();
+            Dispatcher.Post(() =>
+            {
+                try
+                {
+                    action();
+                    tcs.SetResult(null);
+                }
+                catch (Exception e)
+                {
+                    tcs.SetException(e);
+                }
+            });
+            return tcs.Task;
+        }
+
         /// <summary>
         /// Determing if we're currently running in design mode
         /// </summary>

StyletUnitTests/ExecuteTests.cs

@@ -21,7 +21,7 @@ namespace StyletUnitTests
         }
 
         [Test]
-        public void OnUIThreadExecutesUsingDispatcher()
+        public void OnUIThreadSyncExecutesUsingDispatcher()
         {
             var sync = new Mock<IDispatcher>();
             Execute.Dispatcher = sync.Object;
@@ -38,7 +38,22 @@ namespace StyletUnitTests
         }
 
         [Test]
-        public void BeginOnUIThreadExecutesUsingDispatcher()
+        public void OnUIThreadSyncExecutesSynchronouslyIfDispatcherIsCurrent()
+        {
+            var sync = new Mock<IDispatcher>();
+            Execute.Dispatcher = sync.Object;
+
+            sync.SetupGet(x => x.IsCurrent).Returns(true);
+
+            bool actionCalled = false;
+            Execute.OnUIThreadSync(() => actionCalled = true);
+
+            Assert.IsTrue(actionCalled);
+            sync.Verify(x => x.Send(It.IsAny<Action>()), Times.Never);
+        }
+
+        [Test]
+        public void PostToUIThreadExecutesUsingDispatcher()
         {
             var sync = new Mock<IDispatcher>();
             Execute.Dispatcher = sync.Object;
@@ -55,7 +70,26 @@ namespace StyletUnitTests
         }
 
         [Test]
-        public void BeginOnUIThreadOrSynchronousExecutesUsingDispatcherIfNotCurrent()
+        public void PostToUIThreadAsyncExecutesUsingDispatcher()
+        {
+            var sync = new Mock<IDispatcher>();
+            Execute.Dispatcher = sync.Object;
+
+            Action passedAction = null;
+            sync.Setup(x => x.Post(It.IsAny<Action>())).Callback((Action a) => passedAction = a);
+
+            bool actionCalled = false;
+            var task = Execute.PostToUIThreadAsync(() => actionCalled = true);
+
+            Assert.IsFalse(task.IsCompleted);
+            Assert.IsFalse(actionCalled);
+            passedAction();
+            Assert.IsTrue(actionCalled);
+            Assert.IsTrue(task.IsCompleted);
+        }
+
+        [Test]
+        public void OnUIThreadExecutesUsingDispatcherIfNotCurrent()
         {
             var sync = new Mock<IDispatcher>();
             Execute.Dispatcher = sync.Object;
@@ -91,7 +125,7 @@ namespace StyletUnitTests
         }
 
         [Test]
-        public void OnUIThreadPropagatesException()
+        public void OnUIThreadSyncPropagatesException()
         {
             var sync = new Mock<IDispatcher>();
             Execute.Dispatcher = sync.Object;
@@ -125,21 +159,45 @@ namespace StyletUnitTests
         }
 
         [Test]
-        public void ThrowsIfBeginOnUIThreadCalledWithNoDispatcher()
+        public void PostToUIThreadAsyncPrepagatesException()
+        {
+            var sync = new Mock<IDispatcher>();
+            Execute.Dispatcher = sync.Object;
+
+            Action passedAction = null;
+            sync.Setup(x => x.Post(It.IsAny<Action>())).Callback((Action a) => passedAction = a);
+
+            var ex = new Exception("test");
+            var task = Execute.PostToUIThreadAsync(() => { throw ex; });
+
+            passedAction();
+            Assert.IsTrue(task.IsFaulted);
+            Assert.AreEqual(ex, task.Exception.InnerExceptions[0]);
+        }
+
+        [Test]
+        public void ThrowsIfPostToUIThreadCalledWithNoDispatcher()
         {
             Execute.Dispatcher = null;
             Assert.Throws<InvalidOperationException>(() => Execute.PostToUIThread(() => { }));
         }
 
         [Test]
-        public void ThrowsIfBeginOnUIThreadOrSynchronousCalledWithNoDispatcher()
+        public void ThrowsIfPostToUIThreadAsyncCalledWithNoDispatcher()
+        {
+            Execute.Dispatcher = null;
+            Assert.Throws<InvalidOperationException>(() => Execute.PostToUIThreadAsync(() => { }));
+        }
+
+        [Test]
+        public void ThrowsIfOnUIThreadCalledWithNoDispatcher()
         {
             Execute.Dispatcher = null;
             Assert.Throws<InvalidOperationException>(() => Execute.OnUIThread(() => { }));
         }
 
         [Test]
-        public void ThrowsIfOnUIThreadCalledWithNoDispatcher()
+        public void ThrowsIfOnUIThreadSyncCalledWithNoDispatcher()
         {
             Execute.Dispatcher = null;
             Assert.Throws<InvalidOperationException>(() => Execute.OnUIThreadSync(() => { }));
@@ -153,7 +211,7 @@ namespace StyletUnitTests
         }
 
         [Test]
-        public void BeginOnUIThreadExecutesSynchronouslyIfTestExecuteSynchronouslySet()
+        public void PostToUIThreadExecutesSynchronouslyIfTestExecuteSynchronouslySet()
         {
             Execute.TestExecuteSynchronously = true;
 
@@ -164,7 +222,19 @@ namespace StyletUnitTests
         }
 
         [Test]
-        public void OnUIThreadExecutesSynchronouslyIfTestExecuteSynchronouslySet()
+        public void PostToUIThreadAsyncExecutesSynchronouslyIfTestExecuteSynchronouslySet()
+        {
+            Execute.TestExecuteSynchronously = true;
+
+            Execute.Dispatcher = null;
+            bool called = false;
+            var task = Execute.PostToUIThreadAsync(() => called = true);
+            Assert.True(called);
+            Assert.True(task.IsCompleted);
+        }
+
+        [Test]
+        public void OnUIThreadSyncExecutesSynchronouslyIfTestExecuteSynchronouslySet()
         {
             Execute.TestExecuteSynchronously = true;