Don't have async void tests.

That's bad. Also un-skip binding expression tests.

tests/Avalonia.Markup.UnitTests/ControlLocatorTests.cs

@@ -4,6 +4,7 @@
 using System;
 using System.Collections.Generic;
 using System.Reactive.Linq;
+using System.Threading.Tasks;
 using Avalonia.Controls;
 using Avalonia.UnitTests;
 using Xunit;
@@ -13,7 +14,7 @@ namespace Avalonia.Markup.UnitTests
     public class ControlLocatorTests
     {
         [Fact]
-        public async void Track_By_Name_Should_Find_Control_Added_Earlier()
+        public async Task Track_By_Name_Should_Find_Control_Added_Earlier()
         {
             TextBlock target;
             TextBlock relativeTo;

tests/Avalonia.Markup.UnitTests/Data/BindingExpressionTests.cs

@@ -6,6 +6,7 @@ using System.Collections.Generic;
 using System.Globalization;
 using System.Reactive.Linq;
 using System.Threading;
+using System.Threading.Tasks;
 using Avalonia.Data;
 using Avalonia.Markup.Data;
 using Avalonia.UnitTests;
@@ -17,7 +18,7 @@ namespace Avalonia.Markup.UnitTests.Data
     public class BindingExpressionTests : IClassFixture<InvariantCultureFixture>
     {
         [Fact]
-        public async void Should_Get_Simple_Property_Value()
+        public async Task Should_Get_Simple_Property_Value()
         {
             var data = new Class1 { StringValue = "foo" };
             var target = new BindingExpression(new ExpressionObserver(data, "StringValue"), typeof(string));
@@ -49,7 +50,7 @@ namespace Avalonia.Markup.UnitTests.Data
         }
 
         [Fact]
-        public async void Should_Convert_Get_String_To_Double()
+        public async Task Should_Convert_Get_String_To_Double()
         {
             var data = new Class1 { StringValue = "5.6" };
             var target = new BindingExpression(new ExpressionObserver(data, "StringValue"), typeof(double));
@@ -59,7 +60,7 @@ namespace Avalonia.Markup.UnitTests.Data
         }
 
         [Fact]
-        public async void Getting_Invalid_Double_String_Should_Return_BindingError()
+        public async Task Getting_Invalid_Double_String_Should_Return_BindingError()
         {
             var data = new Class1 { StringValue = "foo" };
             var target = new BindingExpression(new ExpressionObserver(data, "StringValue"), typeof(double));
@@ -69,7 +70,7 @@ namespace Avalonia.Markup.UnitTests.Data
         }
 
         [Fact]
-        public async void Should_Coerce_Get_Null_Double_String_To_UnsetValue()
+        public async Task Should_Coerce_Get_Null_Double_String_To_UnsetValue()
         {
             var data = new Class1 { StringValue = null };
             var target = new BindingExpression(new ExpressionObserver(data, "StringValue"), typeof(double));
@@ -90,7 +91,7 @@ namespace Avalonia.Markup.UnitTests.Data
         }
 
         [Fact]
-        public async void Should_Convert_Get_Double_To_String()
+        public async Task Should_Convert_Get_Double_To_String()
         {
             var data = new Class1 { DoubleValue = 5.6 };
             var target = new BindingExpression(new ExpressionObserver(data, "DoubleValue"), typeof(string));
@@ -111,7 +112,7 @@ namespace Avalonia.Markup.UnitTests.Data
         }
 
         [Fact]
-        public async void Should_Return_BindingNotification_With_FallbackValue_For_NonConvertibe_Target_Value()
+        public async Task Should_Return_BindingNotification_With_FallbackValue_For_NonConvertibe_Target_Value()
         {
             var data = new Class1 { StringValue = "foo" };
             var target = new BindingExpression(
@@ -130,7 +131,7 @@ namespace Avalonia.Markup.UnitTests.Data
         }
 
         [Fact]
-        public async void Should_Return_BindingNotification_With_FallbackValue_For_NonConvertibe_Target_Value_With_Data_Validation()
+        public async Task Should_Return_BindingNotification_With_FallbackValue_For_NonConvertibe_Target_Value_With_Data_Validation()
         {
             var data = new Class1 { StringValue = "foo" };
             var target = new BindingExpression(
@@ -149,7 +150,7 @@ namespace Avalonia.Markup.UnitTests.Data
         }
 
         [Fact(Skip="Result is not always AggregateException.")]
-        public async void Should_Return_BindingNotification_For_Invalid_FallbackValue()
+        public async Task Should_Return_BindingNotification_For_Invalid_FallbackValue()
         {
             var data = new Class1 { StringValue = "foo" };
             var target = new BindingExpression(
@@ -169,7 +170,7 @@ namespace Avalonia.Markup.UnitTests.Data
         }
 
         [Fact(Skip="Result is not always AggregateException.")]
-        public async void Should_Return_BindingNotification_For_Invalid_FallbackValue_With_Data_Validation()
+        public async Task Should_Return_BindingNotification_For_Invalid_FallbackValue_With_Data_Validation()
         {
             var data = new Class1 { StringValue = "foo" };
             var target = new BindingExpression(
@@ -236,11 +237,12 @@ namespace Avalonia.Markup.UnitTests.Data
             Assert.Equal(0, data.DoubleValue);
         }
 
-        [Fact(Skip="Moq.MockException")]
+        [Fact]
         public void Should_Pass_ConverterParameter_To_Convert()
         {
             var data = new Class1 { DoubleValue = 5.6 };
             var converter = new Mock<IValueConverter>();
+
             var target = new BindingExpression(
                 new ExpressionObserver(data, "DoubleValue"),
                 typeof(string),
@@ -249,10 +251,10 @@ namespace Avalonia.Markup.UnitTests.Data
 
             target.Subscribe(_ => { });
 
-            converter.Verify(x => x.Convert(5.6, typeof(string), "foo", CultureInfo.InvariantCulture));
+            converter.Verify(x => x.Convert(5.6, typeof(string), "foo", CultureInfo.CurrentCulture));
         }
 
-        [Fact(Skip="Moq.MockException")]
+        [Fact]
         public void Should_Pass_ConverterParameter_To_ConvertBack()
         {
             var data = new Class1 { DoubleValue = 5.6 };
@@ -265,7 +267,7 @@ namespace Avalonia.Markup.UnitTests.Data
 
             target.OnNext("bar");
 
-            converter.Verify(x => x.ConvertBack("bar", typeof(double), "foo", CultureInfo.InvariantCulture));
+            converter.Verify(x => x.ConvertBack("bar", typeof(double), "foo", CultureInfo.CurrentCulture));
         }
 
         [Fact(Skip="Moq.MockException")]

tests/Avalonia.Markup.UnitTests/Data/ExpressionObserverTests_AttachedProperty.cs

@@ -4,6 +4,7 @@
 using System;
 using System.Collections.Generic;
 using System.Reactive.Linq;
+using System.Threading.Tasks;
 using Avalonia.Diagnostics;
 using Avalonia.Markup.Data;
 using Xunit;
@@ -18,7 +19,7 @@ namespace Avalonia.Markup.UnitTests.Data
         }
 
         [Fact]
-        public async void Should_Get_Attached_Property_Value()
+        public async Task Should_Get_Attached_Property_Value()
         {
             var data = new Class1();
             var target = new ExpressionObserver(data, "(Owner.Foo)");
@@ -30,7 +31,7 @@ namespace Avalonia.Markup.UnitTests.Data
         }
 
         [Fact]
-        public async void Should_Get_Chained_Attached_Property_Value()
+        public async Task Should_Get_Chained_Attached_Property_Value()
         {
             var data = new Class1
             {

tests/Avalonia.Markup.UnitTests/Data/ExpressionObserverTests_AvaloniaProperty.cs

@@ -4,6 +4,7 @@
 using System;
 using System.Collections.Generic;
 using System.Reactive.Linq;
+using System.Threading.Tasks;
 using Avalonia.Diagnostics;
 using Avalonia.Markup.Data;
 using Xunit;
@@ -18,7 +19,7 @@ namespace Avalonia.Markup.UnitTests.Data
         }
 
         [Fact]
-        public async void Should_Get_Simple_Property_Value()
+        public async Task Should_Get_Simple_Property_Value()
         {
             var data = new Class1();
             var target = new ExpressionObserver(data, "Foo");

tests/Avalonia.Markup.UnitTests/Data/ExpressionObserverTests_Indexer.cs

@@ -5,6 +5,7 @@ using System;
 using System.Collections.Generic;
 using System.Collections.ObjectModel;
 using System.Reactive.Linq;
+using System.Threading.Tasks;
 using Avalonia.Collections;
 using Avalonia.Diagnostics;
 using Avalonia.Markup.Data;
@@ -16,7 +17,7 @@ namespace Avalonia.Markup.UnitTests.Data
     public class ExpressionObserverTests_Indexer
     {
         [Fact]
-        public async void Should_Get_Array_Value()
+        public async Task Should_Get_Array_Value()
         {
             var data = new { Foo = new [] { "foo", "bar" } };
             var target = new ExpressionObserver(data, "Foo[1]");
@@ -26,7 +27,7 @@ namespace Avalonia.Markup.UnitTests.Data
         }
 
         [Fact]
-        public async void Should_Get_UnsetValue_For_Invalid_Array_Index()
+        public async Task Should_Get_UnsetValue_For_Invalid_Array_Index()
         {
             var data = new { Foo = new[] { "foo", "bar" } };
             var target = new ExpressionObserver(data, "Foo[invalid]");
@@ -36,7 +37,7 @@ namespace Avalonia.Markup.UnitTests.Data
         }
 
         [Fact]
-        public async void Should_Get_UnsetValue_For_Invalid_Dictionary_Index()
+        public async Task Should_Get_UnsetValue_For_Invalid_Dictionary_Index()
         {
             var data = new { Foo = new Dictionary<int, string> { { 1, "foo" } } };
             var target = new ExpressionObserver(data, "Foo[invalid]");
@@ -46,7 +47,7 @@ namespace Avalonia.Markup.UnitTests.Data
         }
 
         [Fact]
-        public async void Should_Get_UnsetValue_For_Object_Without_Indexer()
+        public async Task Should_Get_UnsetValue_For_Object_Without_Indexer()
         {
             var data = new { Foo = 5 };
             var target = new ExpressionObserver(data, "Foo[noindexer]");
@@ -56,7 +57,7 @@ namespace Avalonia.Markup.UnitTests.Data
         }
 
         [Fact]
-        public async void Should_Get_MultiDimensional_Array_Value()
+        public async Task Should_Get_MultiDimensional_Array_Value()
         {
             var data = new { Foo = new[,] { { "foo", "bar" }, { "baz", "qux" } } };
             var target = new ExpressionObserver(data, "Foo[1, 1]");
@@ -66,7 +67,7 @@ namespace Avalonia.Markup.UnitTests.Data
         }
 
         [Fact]
-        public async void Should_Get_Value_For_String_Indexer()
+        public async Task Should_Get_Value_For_String_Indexer()
         {
             var data = new { Foo = new Dictionary<string, string> { { "foo", "bar" }, { "baz", "qux" } } };
             var target = new ExpressionObserver(data, "Foo[foo]");
@@ -76,7 +77,7 @@ namespace Avalonia.Markup.UnitTests.Data
         }
 
         [Fact]
-        public async void Should_Get_Value_For_Non_String_Indexer()
+        public async Task Should_Get_Value_For_Non_String_Indexer()
         {
             var data = new { Foo = new Dictionary<double, string> { { 1.0, "bar" }, { 2.0, "qux" } } };
             var target = new ExpressionObserver(data, "Foo[1.0]");
@@ -86,7 +87,7 @@ namespace Avalonia.Markup.UnitTests.Data
         }
 
         [Fact]
-        public async void Array_Out_Of_Bounds_Should_Return_UnsetValue()
+        public async Task Array_Out_Of_Bounds_Should_Return_UnsetValue()
         {
             var data = new { Foo = new[] { "foo", "bar" } };
             var target = new ExpressionObserver(data, "Foo[2]");
@@ -96,7 +97,7 @@ namespace Avalonia.Markup.UnitTests.Data
         }
 
         [Fact]
-        public async void Array_With_Wrong_Dimensions_Should_Return_UnsetValue()
+        public async Task Array_With_Wrong_Dimensions_Should_Return_UnsetValue()
         {
             var data = new { Foo = new[] { "foo", "bar" } };
             var target = new ExpressionObserver(data, "Foo[1,2]");
@@ -106,7 +107,7 @@ namespace Avalonia.Markup.UnitTests.Data
         }
 
         [Fact]
-        public async void List_Out_Of_Bounds_Should_Return_UnsetValue()
+        public async Task List_Out_Of_Bounds_Should_Return_UnsetValue()
         {
             var data = new { Foo = new List<string> { "foo", "bar" } };
             var target = new ExpressionObserver(data, "Foo[2]");
@@ -116,7 +117,7 @@ namespace Avalonia.Markup.UnitTests.Data
         }
 
         [Fact]
-        public async void Should_Get_List_Value()
+        public async Task Should_Get_List_Value()
         {
             var data = new { Foo = new List<string> { "foo", "bar" } };
             var target = new ExpressionObserver(data, "Foo[1]");

tests/Avalonia.Markup.UnitTests/Data/ExpressionObserverTests_Negation.cs

@@ -3,6 +3,7 @@
 
 using System;
 using System.Reactive.Linq;
+using System.Threading.Tasks;
 using Avalonia.Data;
 using Avalonia.Markup.Data;
 using Xunit;
@@ -12,7 +13,7 @@ namespace Avalonia.Markup.UnitTests.Data
     public class ExpressionObserverTests_Negation
     {
         [Fact]
-        public async void Should_Negate_Boolean_Value()
+        public async Task Should_Negate_Boolean_Value()
         {
             var data = new { Foo = true };
             var target = new ExpressionObserver(data, "!Foo");
@@ -22,7 +23,7 @@ namespace Avalonia.Markup.UnitTests.Data
         }
 
         [Fact]
-        public async void Should_Negate_0()
+        public async Task Should_Negate_0()
         {
             var data = new { Foo = 0 };
             var target = new ExpressionObserver(data, "!Foo");
@@ -32,7 +33,7 @@ namespace Avalonia.Markup.UnitTests.Data
         }
 
         [Fact]
-        public async void Should_Negate_1()
+        public async Task Should_Negate_1()
         {
             var data = new { Foo = 1 };
             var target = new ExpressionObserver(data, "!Foo");
@@ -42,7 +43,7 @@ namespace Avalonia.Markup.UnitTests.Data
         }
 
         [Fact]
-        public async void Should_Negate_False_String()
+        public async Task Should_Negate_False_String()
         {
             var data = new { Foo = "false" };
             var target = new ExpressionObserver(data, "!Foo");
@@ -52,7 +53,7 @@ namespace Avalonia.Markup.UnitTests.Data
         }
 
         [Fact]
-        public async void Should_Negate_True_String()
+        public async Task Should_Negate_True_String()
         {
             var data = new { Foo = "True" };
             var target = new ExpressionObserver(data, "!Foo");
@@ -62,7 +63,7 @@ namespace Avalonia.Markup.UnitTests.Data
         }
 
         [Fact]
-        public async void Should_Return_BindingNotification_For_String_Not_Convertible_To_Boolean()
+        public async Task Should_Return_BindingNotification_For_String_Not_Convertible_To_Boolean()
         {
             var data = new { Foo = "foo" };
             var target = new ExpressionObserver(data, "!Foo");
@@ -76,7 +77,7 @@ namespace Avalonia.Markup.UnitTests.Data
         }
 
         [Fact]
-        public async void Should_Return_BindingNotification_For_Value_Not_Convertible_To_Boolean()
+        public async Task Should_Return_BindingNotification_For_Value_Not_Convertible_To_Boolean()
         {
             var data = new { Foo = new object() };
             var target = new ExpressionObserver(data, "!Foo");

tests/Avalonia.Markup.UnitTests/Data/ExpressionObserverTests_Property.cs

@@ -11,13 +11,14 @@ using Avalonia.Data;
 using Avalonia.Markup.Data;
 using Avalonia.UnitTests;
 using Xunit;
+using System.Threading.Tasks;
 
 namespace Avalonia.Markup.UnitTests.Data
 {
     public class ExpressionObserverTests_Property
     {
         [Fact]
-        public async void Should_Get_Simple_Property_Value()
+        public async Task Should_Get_Simple_Property_Value()
         {
             var data = new { Foo = "foo" };
             var target = new ExpressionObserver(data, "Foo");
@@ -38,7 +39,7 @@ namespace Avalonia.Markup.UnitTests.Data
         }
 
         [Fact]
-        public async void Should_Get_Simple_Property_Value_Null()
+        public async Task Should_Get_Simple_Property_Value_Null()
         {
             var data = new { Foo = (string)null };
             var target = new ExpressionObserver(data, "Foo");
@@ -48,7 +49,7 @@ namespace Avalonia.Markup.UnitTests.Data
         }
 
         [Fact]
-        public async void Should_Get_Simple_Property_From_Base_Class()
+        public async Task Should_Get_Simple_Property_From_Base_Class()
         {
             var data = new Class3 { Foo = "foo" };
             var target = new ExpressionObserver(data, "Foo");
@@ -58,7 +59,7 @@ namespace Avalonia.Markup.UnitTests.Data
         }
 
         [Fact]
-        public async void Should_Return_UnsetValue_For_Root_Null()
+        public async Task Should_Return_UnsetValue_For_Root_Null()
         {
             var data = new Class3 { Foo = "foo" };
             var target = new ExpressionObserver(default(object), "Foo");
@@ -68,7 +69,7 @@ namespace Avalonia.Markup.UnitTests.Data
         }
 
         [Fact]
-        public async void Should_Return_UnsetValue_For_Root_UnsetValue()
+        public async Task Should_Return_UnsetValue_For_Root_UnsetValue()
         {
             var data = new Class3 { Foo = "foo" };
             var target = new ExpressionObserver(AvaloniaProperty.UnsetValue, "Foo");
@@ -78,7 +79,7 @@ namespace Avalonia.Markup.UnitTests.Data
         }
 
         [Fact]
-        public async void Should_Return_UnsetValue_For_Observable_Root_Null()
+        public async Task Should_Return_UnsetValue_For_Observable_Root_Null()
         {
             var data = new Class3 { Foo = "foo" };
             var target = new ExpressionObserver(Observable.Return(default(object)), "Foo");
@@ -88,7 +89,7 @@ namespace Avalonia.Markup.UnitTests.Data
         }
 
         [Fact]
-        public async void Should_Return_UnsetValue_For_Observable_Root_UnsetValue()
+        public async Task Should_Return_UnsetValue_For_Observable_Root_UnsetValue()
         {
             var data = new Class3 { Foo = "foo" };
             var target = new ExpressionObserver(Observable.Return(AvaloniaProperty.UnsetValue), "Foo");
@@ -98,7 +99,7 @@ namespace Avalonia.Markup.UnitTests.Data
         }
 
         [Fact]
-        public async void Should_Get_Simple_Property_Chain()
+        public async Task Should_Get_Simple_Property_Chain()
         {
             var data = new { Foo = new { Bar = new { Baz = "baz" } }  };
             var target = new ExpressionObserver(data, "Foo.Bar.Baz");
@@ -119,7 +120,7 @@ namespace Avalonia.Markup.UnitTests.Data
         }
 
         [Fact]
-        public async void Should_Return_BindingNotification_Error_For_Broken_Chain()
+        public async Task Should_Return_BindingNotification_Error_For_Broken_Chain()
         {
             var data = new { Foo = new { Bar = 1 } };
             var target = new ExpressionObserver(data, "Foo.Bar.Baz");

tests/Avalonia.Markup.Xaml.UnitTests/Data/MultiBindingTests.cs

@@ -10,13 +10,14 @@ using Moq;
 using Avalonia.Controls;
 using Avalonia.Markup.Xaml.Data;
 using Xunit;
+using System.Threading.Tasks;
 
 namespace Avalonia.Markup.Xaml.UnitTests.Data
 {
     public class MultiBindingTests
     {
         [Fact]
-        public async void OneWay_Binding_Should_Be_Set_Up()
+        public async Task OneWay_Binding_Should_Be_Set_Up()
         {
             var source = new { A = 1, B = 2, C = 3 };
             var binding = new MultiBinding

tests/Avalonia.Styling.UnitTests/SelectorTests_Child.cs

@@ -6,6 +6,7 @@ using System.Collections.Generic;
 using System.Linq;
 using System.Reactive;
 using System.Reactive.Linq;
+using System.Threading.Tasks;
 using Avalonia.Collections;
 using Avalonia.Controls;
 using Avalonia.Data;
@@ -45,7 +46,7 @@ namespace Avalonia.Styling.UnitTests
         }
 
         [Fact]
-        public async void Child_Matches_Control_When_It_Is_Child_OfType_And_Class()
+        public async Task Child_Matches_Control_When_It_Is_Child_OfType_And_Class()
         {
             var parent = new TestLogical1();
             var child = new TestLogical2();