Write a test to verify RegisterAsyncTask + ThrownExceptions behavior. Fixes #501

Author: anaisbetts

ReactiveUI.Tests/ReactiveCommandTest.cs

@@ -533,5 +533,41 @@ public void CombinedCommandsShouldReflectParentCanExecute()
             Assert.Equal(3, canExecuteOutput.Count);
             Assert.Equal(true, canExecuteOutput[2]);
         }
+
+        [Fact]
+        public void TaskExceptionsShouldBeMarshaledToThrownExceptions()
+        {
+            (new TestScheduler()).With(sched => {
+                var fixture = new ReactiveCommand();
+
+                int result = 0;
+                fixture.RegisterAsyncTask(async _ => {
+                    await Observable.Timer(TimeSpan.FromMilliseconds(50), RxApp.TaskpoolScheduler);
+                    throw new Exception("Die");
+                    return 5;
+                }).Subscribe(x => result = x);
+
+                var error = default(Exception);
+                fixture.ThrownExceptions.Subscribe(ex => error = ex);
+
+                fixture.Execute(null);
+
+                sched.AdvanceByMs(20);
+                Assert.Null(error);
+                Assert.Equal(0, result);
+
+                // NB: We have to Thread.Sleep here to compensate for not being
+                // able to control the concurrency of Task
+                sched.AdvanceByMs(100);
+                Thread.Sleep(100);
+
+                // NB: Advance it one more so that the scheduled ThrownExceptions
+                // end up being dispatched
+                sched.AdvanceByMs(10);
+
+                Assert.NotNull(error);
+                Assert.Equal(0, result);
+            });
+        }
     }
 }

ReactiveUI/Interfaces.cs

@@ -451,4 +451,4 @@ public class ViewContractAttribute : Attribute
     }
 }
 
-// vim: tw=120 ts=4 sw=4 et :
+// vim: tw=120 ts=4 sw=4 et :

ReactiveUI/ReactiveUI.csproj

@@ -66,6 +66,7 @@
     <Compile Include="..\CommonAssemblyInfo.cs">
       <Link>Properties\CommonAssemblyInfo.cs</Link>
     </Compile>
+    <Compile Include="Activation.cs" />
     <Compile Include="ReactiveBinding.cs" />
     <Compile Include="AutoPersistHelper.cs" />
     <Compile Include="BindingTypeConverters.cs" />