Merge pull request #1005 from Caliburn-Micro/publish_ui_tests

Add unit tests for EventAggregator thread behavior

Author: vb2ae

src/Caliburn.Micro.Core.Tests/EventAggregatorExtensionsTests.cs

@@ -0,0 +1,95 @@
+using System;
+using System.Threading;
+using System.Threading.Tasks;
+using Moq;
+using Xunit;
+namespace Caliburn.Micro.Core.Tests
+{
+    public class EventAggregatorExtensionsTests
+    {
+        const int NumberOfMockTargets = 20;
+        [Fact]
+        public void SubscribeOnUIThread_CallsSubscribeWithUIThreadMarshaller()
+        {
+            var mockAggregator = new Mock<IEventAggregator>();
+            var subscriber = new object();
+
+            Func<Func<Task>, Task> capturedMarshaller = null;
+            mockAggregator.Setup(x => x.Subscribe(subscriber, It.IsAny<Func<Func<Task>, Task>>()))
+                .Callback<object, Func<Func<Task>, Task>>((_, m) => capturedMarshaller = m);
+
+            mockAggregator.Object.SubscribeOnUIThread(subscriber);
+
+            Assert.NotNull(capturedMarshaller);
+            // UI thread marshaler returns a Task
+            var taskSource = new TaskCompletionSource<bool>();
+            var task = capturedMarshaller(() => { taskSource.SetResult(true); return taskSource.Task; });
+            Assert.IsAssignableFrom<Task>(task);
+        }
+
+        [Fact]
+        public async Task PublishOnCurrentThreadAsync_CallsPublishAsyncWithDirectMarshaller()
+        {
+            var eventAggregator = new EventAggregator();
+            string message = "Test";
+            using (var tokenSource = new CancellationTokenSource())
+            {
+                var cancellationToken = tokenSource.Token;
+                var mockTarget1 = new Mock<IHandle<string>>();
+                var mockTarget2 = new Mock<IHandle<string>>();
+                eventAggregator.SubscribeOnPublishedThread(mockTarget1.Object);
+                eventAggregator.SubscribeOnPublishedThread(mockTarget2.Object);
+                await eventAggregator.PublishOnCurrentThreadAsync(message, cancellationToken);
+
+                mockTarget1.Verify(x => x.HandleAsync(message, cancellationToken), Times.Once);
+                mockTarget2.Verify(x => x.HandleAsync(message, cancellationToken), Times.Once);
+            }
+        }
+
+
+        [Fact]
+        public async Task PublishOnBackgroundThreadAsync_CallsPublishAsyncWithBackgroundMarshaller()
+        {
+            var eventAggregator = new EventAggregator();
+            var message = new object();
+            using (var tokenSource = new CancellationTokenSource())
+            {
+                var cancellationToken = tokenSource.Token;
+                var mockTarget1 = new Mock<IHandle<object>>();
+                eventAggregator.SubscribeOnPublishedThread(mockTarget1.Object);
+
+
+                await eventAggregator.PublishOnBackgroundThreadAsync(message, cancellationToken);
+
+                mockTarget1.Verify(x => x.HandleAsync(message, cancellationToken), Times.Once);
+            }
+        }
+
+        [Fact]
+        public async Task PublishOnCurrentThreadAsync_CallsHandleAsyncOnAllSubscribedTargets()
+        {
+            var eventAggregator = new EventAggregator();
+            string message = "Test";
+            using (var tokenSource = new CancellationTokenSource())
+            {
+                var cancellationToken = tokenSource.Token;
+
+                // Create 20 mock targets
+                var mockTargets = new Mock<IHandle<string>>[NumberOfMockTargets];
+                for (int i = 0; i < mockTargets.Length; i++)
+                {
+                    mockTargets[i] = new Mock<IHandle<string>>();
+                    eventAggregator.SubscribeOnPublishedThread(mockTargets[i].Object);
+                }
+
+                await eventAggregator.PublishOnCurrentThreadAsync(message, cancellationToken);
+
+                // Verify HandleAsync was called on each
+                foreach (var mockTarget in mockTargets)
+                {
+                    mockTarget.Verify(x => x.HandleAsync(message, cancellationToken), Times.Once);
+                }
+            }
+        }
+    }
+}