[Tests] Ensure async void exceptions propagate correctly

This should ensure that exceptions thrown inside async void
methods do get rethrown as part of the Teardown of a given test.

This removes the eventhandlers on AppDomain.UnhandledException
and also removes the second SyncContext implementation which
did not capture/propagate the exceptions.

9 files changed, 22 insertions, 71 deletions

diff --git a/Xamarin.PropertyEditing.Tests/AddValueConverterViewModelTests.cs b/Xamarin.PropertyEditing.Tests/AddValueConverterViewModelTests.cs
index c323cc2..e107c19 100644
--- a/Xamarin.PropertyEditing.Tests/AddValueConverterViewModelTests.cs
+++ b/Xamarin.PropertyEditing.Tests/AddValueConverterViewModelTests.cs
@@ -14,15 +14,15 @@ namespace Xamarin.PropertyEditing.Tests
 		[SetUp]
 		public void Setup ()
 		{
-			this.syncContext = new AsyncSynchronizationContext ();
+			this.syncContext = new TestContext ();
 			SynchronizationContext.SetSynchronizationContext (this.syncContext);
 		}
 
 		[TearDown]
 		public void TearDown ()
 		{
-			this.syncContext.WaitForPendingOperationsToComplete ();
 			SynchronizationContext.SetSynchronizationContext (null);
+			this.syncContext.ThrowPendingExceptions ();
 		}
 
 		[Test]
@@ -75,6 +75,6 @@ namespace Xamarin.PropertyEditing.Tests
 			Assert.That (vm.ConverterName, Is.EqualTo (type.Name));
 		}
 
-		private AsyncSynchronizationContext syncContext;
+		private TestContext syncContext;
 	}
 }
diff --git a/Xamarin.PropertyEditing.Tests/AsyncSynchronizationContext.cs b/Xamarin.PropertyEditing.Tests/AsyncSynchronizationContext.cs
deleted file mode 100644
index 34a7086..0000000
--- a/Xamarin.PropertyEditing.Tests/AsyncSynchronizationContext.cs
+++ /dev/null
@@ -1,17 +0,0 @@
-using System.Threading;
-
-namespace Xamarin.PropertyEditing.Tests
-{
-	internal class AsyncSynchronizationContext
-		: SynchronizationContext
-	{
-		public override void Post (SendOrPostCallback d, object state)
-		{
-			d (state);
-		}
-
-		public void WaitForPendingOperationsToComplete ()
-		{
-		}
-	}
-}
\ No newline at end of file
diff --git a/Xamarin.PropertyEditing.Tests/CollectionPropertyViewModelTests.cs b/Xamarin.PropertyEditing.Tests/CollectionPropertyViewModelTests.cs
index 7f87448..daaa32d 100644
--- a/Xamarin.PropertyEditing.Tests/CollectionPropertyViewModelTests.cs
+++ b/Xamarin.PropertyEditing.Tests/CollectionPropertyViewModelTests.cs
@@ -16,20 +16,20 @@ namespace Xamarin.PropertyEditing.Tests
 	[TestFixture]
 	internal class CollectionPropertyViewModelTests
 	{
-		private AsyncSynchronizationContext syncContext;
+		private TestContext syncContext;
 
 		[SetUp]
 		public void Setup ()
 		{
-			this.syncContext = new AsyncSynchronizationContext ();
+			this.syncContext = new TestContext ();
 			SynchronizationContext.SetSynchronizationContext (this.syncContext);
 		}
 
 		[TearDown]
 		public void TearDown ()
 		{
-			this.syncContext.WaitForPendingOperationsToComplete ();
 			SynchronizationContext.SetSynchronizationContext (null);
+			this.syncContext.ThrowPendingExceptions ();
 		}
 
 		[Test]
diff --git a/Xamarin.PropertyEditing.Tests/CreateBindingViewModelTests.cs b/Xamarin.PropertyEditing.Tests/CreateBindingViewModelTests.cs
index 2cf707b..0c3b16b 100644
--- a/Xamarin.PropertyEditing.Tests/CreateBindingViewModelTests.cs
+++ b/Xamarin.PropertyEditing.Tests/CreateBindingViewModelTests.cs
@@ -22,31 +22,15 @@ namespace Xamarin.PropertyEditing.Tests
 		[SetUp]
 		public void Setup ()
 		{
-			AppDomain.CurrentDomain.UnhandledException += CurrentDomainOnUnhandledException;
-			this.syncContext = new AsyncSynchronizationContext ();
+			this.syncContext = new TestContext ();
 			SynchronizationContext.SetSynchronizationContext (this.syncContext);
 		}
 
-		private Exception unhandled;
-
-		private void CurrentDomainOnUnhandledException (object sender, UnhandledExceptionEventArgs e)
-		{
-			this.unhandled = e.ExceptionObject as Exception;
-		}
-
 		[TearDown]
 		public void TearDown ()
 		{
-			this.syncContext.WaitForPendingOperationsToComplete ();
 			SynchronizationContext.SetSynchronizationContext (null);
-
-			AppDomain.CurrentDomain.UnhandledException -= CurrentDomainOnUnhandledException;
-
-			if (this.unhandled != null) {
-				var ex = this.unhandled;
-				this.unhandled = null;
-				Assert.Fail ("Unhandled exception: {0}", ex);
-			}
+			this.syncContext.ThrowPendingExceptions ();
 		}
 
 		[Test]
@@ -630,7 +614,7 @@ namespace Xamarin.PropertyEditing.Tests
 				vm.BindingProperties.Cast<PropertyViewModel> ().Select (pvm => pvm.Property));
 		}
 
-		private AsyncSynchronizationContext syncContext;
+		private TestContext syncContext;
 		private static readonly ResourceSource[] DefaultResourceSources = new[] { MockResourceProvider.SystemResourcesSource, MockResourceProvider.ApplicationResourcesSource };
 
 		private Mock<IPropertyInfo> GetBasicProperty (string name = "propertyName")
diff --git a/Xamarin.PropertyEditing.Tests/ObjectPropertyViewModelTests.cs b/Xamarin.PropertyEditing.Tests/ObjectPropertyViewModelTests.cs
index 426cdd7..193bc09 100644
--- a/Xamarin.PropertyEditing.Tests/ObjectPropertyViewModelTests.cs
+++ b/Xamarin.PropertyEditing.Tests/ObjectPropertyViewModelTests.cs
@@ -17,15 +17,15 @@ namespace Xamarin.PropertyEditing.Tests
 		[SetUp]
 		public void Setup ()
 		{
-			this.syncContext = new AsyncSynchronizationContext();
+			this.syncContext = new TestContext ();
 			SynchronizationContext.SetSynchronizationContext (this.syncContext);
 		}
 
 		[TearDown]
 		public void TearDown ()
 		{
-			this.syncContext.WaitForPendingOperationsToComplete ();
 			SynchronizationContext.SetSynchronizationContext (null);
+			syncContext.ThrowPendingExceptions ();
 		}
 
 		[Test]
@@ -255,7 +255,7 @@ namespace Xamarin.PropertyEditing.Tests
 			Assert.That (vm.ValueType, Is.Null);
 		}
 
-		private AsyncSynchronizationContext syncContext;
+		private TestContext syncContext;
 
 		private Mock<IEditorProvider> CreateProviderMock (object value, IObjectEditor editor)
 		{
diff --git a/Xamarin.PropertyEditing.Tests/PanelViewModelTests.cs b/Xamarin.PropertyEditing.Tests/PanelViewModelTests.cs
index 7b51e8f..723d86f 100644
--- a/Xamarin.PropertyEditing.Tests/PanelViewModelTests.cs
+++ b/Xamarin.PropertyEditing.Tests/PanelViewModelTests.cs
@@ -17,13 +17,6 @@ namespace Xamarin.PropertyEditing.Tests
 	internal class PanelViewModelTests
 		: PropertiesViewModelTests<PanelViewModel>
 	{
-		[SetUp]
-		public override void Setup ()
-		{
-			base.Setup ();
-			SynchronizationContext.SetSynchronizationContext (this.context = new TestContext ());
-		}
-
 		[Test]
 		[Description ("We must be sure that if the selected objects list changes while the provider is still retrieving that we end up with the right result")]
 		public async Task InteruptedEditorRetrievalResolvesCorrectlyItemAdded ()
diff --git a/Xamarin.PropertyEditing.Tests/PropertiesViewModelTests.cs b/Xamarin.PropertyEditing.Tests/PropertiesViewModelTests.cs
index a7e98a9..6560aa9 100644
--- a/Xamarin.PropertyEditing.Tests/PropertiesViewModelTests.cs
+++ b/Xamarin.PropertyEditing.Tests/PropertiesViewModelTests.cs
@@ -4,6 +4,7 @@ using System.Collections.ObjectModel;
 using System.Collections.Specialized;
 using System.Linq;
 using System.Reflection;
+using System.Threading;
 using System.Threading.Tasks;
 using Moq;
 using NUnit.Framework;
@@ -35,28 +36,19 @@ namespace Xamarin.PropertyEditing.Tests
 			}
 		}
 
-		private Exception unhandled;
+		private TestContext syncContext;
 		[SetUp]
-		public virtual void Setup ()
+		public void Setup ()
 		{
-			AppDomain.CurrentDomain.UnhandledException += CurrentDomainOnUnhandledException;
+			this.syncContext = new TestContext ();
+			SynchronizationContext.SetSynchronizationContext (this.syncContext);
 		}
 
 		[TearDown]
 		public void TearDown ()
 		{
-			AppDomain.CurrentDomain.UnhandledException -= CurrentDomainOnUnhandledException;
-
-			if (this.unhandled != null) {
-				var ex = this.unhandled;
-				this.unhandled = null;
-				Assert.Fail ("Unhandled exception: {0}", ex);
-			}
-		}
-
-		private void CurrentDomainOnUnhandledException (object sender, UnhandledExceptionEventArgs e)
-		{
-			this.unhandled = e.ExceptionObject as Exception;
+			SynchronizationContext.SetSynchronizationContext (null);
+			this.syncContext.ThrowPendingExceptions ();
 		}
 
 		[Test]
diff --git a/Xamarin.PropertyEditing.Tests/PropertyViewModelTests.cs b/Xamarin.PropertyEditing.Tests/PropertyViewModelTests.cs
index bb719e8..2c49a80 100644
--- a/Xamarin.PropertyEditing.Tests/PropertyViewModelTests.cs
+++ b/Xamarin.PropertyEditing.Tests/PropertyViewModelTests.cs
@@ -24,15 +24,15 @@ namespace Xamarin.PropertyEditing.Tests
 		[SetUp]
 		public void Setup ()
 		{
-			this.syncContext = new AsyncSynchronizationContext();
+			this.syncContext = new TestContext ();
 			SynchronizationContext.SetSynchronizationContext (this.syncContext);
 		}
 
 		[TearDown]
 		public void TearDown ()
 		{
-			this.syncContext.WaitForPendingOperationsToComplete ();
 			SynchronizationContext.SetSynchronizationContext (null);
+			this.syncContext.ThrowPendingExceptions ();
 		}
 
 		[Test]
@@ -1467,6 +1467,6 @@ namespace Xamarin.PropertyEditing.Tests
 		}
 
 		private readonly Random rand = new Random (42);
-		private AsyncSynchronizationContext syncContext;
+		private TestContext syncContext;
 	}
 }
\ No newline at end of file
diff --git a/Xamarin.PropertyEditing.Tests/Xamarin.PropertyEditing.Tests.csproj b/Xamarin.PropertyEditing.Tests/Xamarin.PropertyEditing.Tests.csproj
index c5419cd..1e0355f 100644
--- a/Xamarin.PropertyEditing.Tests/Xamarin.PropertyEditing.Tests.csproj
+++ b/Xamarin.PropertyEditing.Tests/Xamarin.PropertyEditing.Tests.csproj
@@ -58,7 +58,6 @@
   </ItemGroup>
   <ItemGroup>
     <Compile Include="AddValueConverterViewModelTests.cs" />
-    <Compile Include="AsyncSynchronizationContext.cs" />
     <Compile Include="AsyncValueTests.cs" />
     <Compile Include="AsyncWorkQueueTests.cs" />
     <Compile Include="BoolViewModelTests.cs" />