Made validation enable-able during binding construction, similar to WPF. Now validation events are only raised when the validation type is enabled on the property.

src/Markup/Perspex.Markup.Xaml/Data/Binding.cs

@@ -77,6 +77,8 @@ namespace Perspex.Markup.Xaml.Data
         /// </summary>
         public object Source { get; set; }
 
+        public ValidationMethods ValidationMethods { get; set; }
+
         /// <inheritdoc/>
         public InstancedBinding Initiate(
             IPerspexObject target, 
@@ -126,7 +128,7 @@ namespace Perspex.Markup.Xaml.Data
                 FallbackValue,
                 Priority);
 
-            return new InstancedBinding(subject, Mode, Priority);
+            return new InstancedBinding(subject, Mode, Priority, ValidationMethods);
         }
 
         private static PathInfo ParsePath(string path)

src/Markup/Perspex.Markup.Xaml/MarkupExtensions/BindingExtension.cs

@@ -29,6 +29,7 @@ namespace Perspex.Markup.Xaml.MarkupExtensions
                 Mode = Mode,
                 Path = Path,
                 Priority = Priority,
+                ValidationMethods = ValidationMethods
             };
         }
 
@@ -40,5 +41,6 @@ namespace Perspex.Markup.Xaml.MarkupExtensions
         public string Path { get; set; }
         public BindingPriority Priority { get; set; } = BindingPriority.LocalValue;
         public object Source { get; set; }
+        public ValidationMethods ValidationMethods { get; set; } = ValidationMethods.None;
     }
 }

src/Markup/Perspex.Markup/Data/Plugins/ExceptionValidationCheckerPlugin.cs

@@ -64,6 +64,11 @@ namespace Perspex.Markup.Data.Plugins
 
             /// <inheritdoc/>
             public override bool IsValid => Exception == null;
+
+            public override bool Match(ValidationMethods enabledMethods)
+            {
+                return (enabledMethods & ValidationMethods.Exceptions) != 0;
+            }
         }
     }
 }

src/Markup/Perspex.Markup/Data/Plugins/IndeiValidationCheckerPlugin.cs

@@ -86,6 +86,11 @@ namespace Perspex.Markup.Data.Plugins
             /// The errors on the given property and on the object as a whole.
             /// </summary>
             public IEnumerable Errors { get; }
+
+            public override bool Match(ValidationMethods enabledMethods)
+            {
+                return (enabledMethods & ValidationMethods.INotifyDataErrorInfo) != 0;
+            }
         }
     }
 }

src/Perspex.Base/Data/BindingOperations.cs

@@ -44,10 +44,10 @@ namespace Perspex.Data
             {
                 case BindingMode.Default:
                 case BindingMode.OneWay:
-                    return target.Bind(property, binding.Observable ?? binding.Subject, binding.Priority);
+                    return target.Bind(property, binding.Observable ?? binding.Subject, binding.Priority, binding.ValidationMethods);
                 case BindingMode.TwoWay:
                     return new CompositeDisposable(
-                        target.Bind(property, binding.Subject, binding.Priority),
+                        target.Bind(property, binding.Subject, binding.Priority, binding.ValidationMethods),
                         target.GetObservable(property).Subscribe(binding.Subject));
                 case BindingMode.OneTime:
                     var source = binding.Subject ?? binding.Observable;

src/Perspex.Base/Data/InstancedBinding.cs

@@ -29,12 +29,16 @@ namespace Perspex.Data
         /// <param name="value">
         /// The value used for the <see cref="BindingMode.OneTime"/> binding.
         /// </param>
+        /// <param name="methods">The validation methods for this binding.</param>
         /// <param name="priority">The binding priority.</param>
-        public InstancedBinding(object value, BindingPriority priority = BindingPriority.LocalValue)
+        public InstancedBinding(object value,
+            BindingPriority priority = BindingPriority.LocalValue,
+            ValidationMethods methods = ValidationMethods.None)
         {
             Mode = BindingMode.OneTime;
             Priority = priority;
             Value = value;
+            ValidationMethods = methods;
         }
 
         /// <summary>
@@ -43,10 +47,12 @@ namespace Perspex.Data
         /// <param name="observable">The observable for a one-way binding.</param>
         /// <param name="mode">The binding mode.</param>
         /// <param name="priority">The binding priority.</param>
+        /// <param name="methods">The validation methods for this binding.</param>
         public InstancedBinding(
             IObservable<object> observable, 
             BindingMode mode = BindingMode.OneWay,
-            BindingPriority priority = BindingPriority.LocalValue)
+            BindingPriority priority = BindingPriority.LocalValue,
+            ValidationMethods methods = ValidationMethods.None)
         {
             Contract.Requires<ArgumentNullException>(observable != null);
 
@@ -60,6 +66,7 @@ namespace Perspex.Data
             Mode = mode;
             Priority = priority;
             Observable = observable;
+            ValidationMethods = methods;
         }
 
         /// <summary>
@@ -68,16 +75,19 @@ namespace Perspex.Data
         /// <param name="subject">The subject for a two-way binding.</param>
         /// <param name="mode">The binding mode.</param>
         /// <param name="priority">The binding priority.</param>
+        /// <param name="methods">The validation methods for this binding.</param>
         public InstancedBinding(
             ISubject<object> subject,
             BindingMode mode = BindingMode.OneWay,
-            BindingPriority priority = BindingPriority.LocalValue)
+            BindingPriority priority = BindingPriority.LocalValue,
+            ValidationMethods methods = ValidationMethods.None)
         {
             Contract.Requires<ArgumentNullException>(subject != null);
 
             Mode = mode;
             Priority = priority;
             Subject = subject;
+            ValidationMethods = methods;
         }
 
         /// <summary>
@@ -104,5 +114,10 @@ namespace Perspex.Data
         /// Gets the subject for a two-way binding.
         /// </summary>
         public ISubject<object> Subject { get; }
+
+        /// <summary>
+        /// Gets the validation methods for this binding.
+        /// </summary>
+        public ValidationMethods ValidationMethods { get; }
     }
 }

src/Perspex.Base/Data/ValidationMethods.cs

@@ -0,0 +1,13 @@
+using System;
+
+namespace Perspex.Data
+{
+    [Flags]
+    public enum ValidationMethods
+    {
+        None = 0,
+        Exceptions = 1,
+        INotifyDataErrorInfo = 2,
+        All = -1
+    }
+}

src/Perspex.Base/Data/ValidationStatus.cs

@@ -19,5 +19,12 @@ namespace Perspex.Data
         /// True when the data passes validation; otherwise, false.
         /// </summary>
         public abstract bool IsValid { get; }
+
+        /// <summary>
+        /// Checks if this validation status came from a currently enabled method of validation checking.
+        /// </summary>
+        /// <param name="enabledMethods">The enabled methods of validation checking.</param>
+        /// <returns>True if enabled; otherwise, false.</returns>
+        public abstract bool Match(ValidationMethods enabledMethods);
     }
 }

src/Perspex.Base/IPerspexObject.cs

@@ -67,13 +67,15 @@ namespace Perspex
         /// <param name="property">The property.</param>
         /// <param name="source">The observable.</param>
         /// <param name="priority">The priority of the binding.</param>
+        /// <param name="validation">The validation methods of the binding.</param>
         /// <returns>
         /// A disposable which can be used to terminate the binding.
         /// </returns>
         IDisposable Bind(
             PerspexProperty property,
             IObservable<object> source,
-            BindingPriority priority = BindingPriority.LocalValue);
+            BindingPriority priority = BindingPriority.LocalValue,
+            ValidationMethods validation = ValidationMethods.None);
 
         /// <summary>
         /// Binds a <see cref="PerspexProperty"/> to an observable.
@@ -82,12 +84,14 @@ namespace Perspex
         /// <param name="property">The property.</param>
         /// <param name="source">The observable.</param>
         /// <param name="priority">The priority of the binding.</param>
+        /// <param name="validation">The validation methods of the binding.</param>
         /// <returns>
         /// A disposable which can be used to terminate the binding.
         /// </returns>
         IDisposable Bind<T>(
             PerspexProperty<T> property,
             IObservable<T> source,
-            BindingPriority priority = BindingPriority.LocalValue);
+            BindingPriority priority = BindingPriority.LocalValue,
+            ValidationMethods validation = ValidationMethods.None);
     }
 }

src/Perspex.Base/Perspex.Base.csproj

@@ -44,6 +44,7 @@
       <Link>Properties\SharedAssemblyInfo.cs</Link>
     </Compile>
     <Compile Include="Data\BindingError.cs" />
+    <Compile Include="Data\ValidationMethods.cs" />
     <Compile Include="Data\ValidationStatus.cs" />
     <Compile Include="Diagnostics\INotifyCollectionChangedDebug.cs" />
     <Compile Include="Data\AssignBindingAttribute.cs" />

src/Perspex.Base/PerspexObject.cs

@@ -375,13 +375,15 @@ namespace Perspex
         /// <param name="property">The property.</param>
         /// <param name="source">The observable.</param>
         /// <param name="priority">The priority of the binding.</param>
+        /// <param name="validation">The validation methods of the binding.</param>
         /// <returns>
         /// A disposable which can be used to terminate the binding.
         /// </returns>
         public IDisposable Bind(
             PerspexProperty property,
             IObservable<object> source,
-            BindingPriority priority = BindingPriority.LocalValue)
+            BindingPriority priority = BindingPriority.LocalValue,
+            ValidationMethods validation = ValidationMethods.None)
         {
             Contract.Requires<ArgumentNullException>(property != null);
             VerifyAccess();
@@ -408,15 +410,16 @@ namespace Perspex
                     .Select(x => CastOrDefault(x, property.PropertyType))
                     .Do(_ => { }, () => s_directBindings.Remove(subscription))
                     .Subscribe(x => DirectBindingSet(property, x));
-                validationSubcription = source.OfType<ValidationStatus>().Subscribe(x => ValidationChanged(property, x));
+                validationSubcription = source
+                    .OfType<ValidationStatus>()
+                    .Where(v => v.Match(validation))
+                    .Subscribe(x => ValidationChanged(property, x));
 
                 s_directBindings.Add(subscription);
-                s_directBindings.Add(validationSubcription);
 
                 return Disposable.Create(() =>
                 {
                     validationSubcription.Dispose();
-                    s_directBindings.Remove(validationSubcription);
                     subscription.Dispose();
                     s_directBindings.Remove(subscription);
                 });
@@ -444,7 +447,7 @@ namespace Perspex
                     GetDescription(source),
                     priority);
 
-                return v.Add(source, (int)priority);
+                return v.Add(source, (int)priority, validation);
             }
         }
 
@@ -455,13 +458,15 @@ namespace Perspex
         /// <param name="property">The property.</param>
         /// <param name="source">The observable.</param>
         /// <param name="priority">The priority of the binding.</param>
+        /// <param name="validation">The validation methods of the binding.</param>
         /// <returns>
         /// A disposable which can be used to terminate the binding.
         /// </returns>
         public IDisposable Bind<T>(
             PerspexProperty<T> property,
             IObservable<T> source,
-            BindingPriority priority = BindingPriority.LocalValue)
+            BindingPriority priority = BindingPriority.LocalValue,
+            ValidationMethods validation = ValidationMethods.None)
         {
             Contract.Requires<ArgumentNullException>(property != null);
 

src/Perspex.Base/PriorityBindingEntry.cs

@@ -13,6 +13,7 @@ namespace Perspex
     {
         private PriorityLevel _owner;
         private IDisposable _subscription;
+        private ValidationMethods _validation;
 
         /// <summary>
         /// Initializes a new instance of the <see cref="PriorityBindingEntry"/> class.
@@ -21,10 +22,12 @@ namespace Perspex
         /// <param name="index">
         /// The binding index. Later bindings should have higher indexes.
         /// </param>
-        public PriorityBindingEntry(PriorityLevel owner, int index)
+        /// <param name="validation">The validation settings for the binding.</param>
+        public PriorityBindingEntry(PriorityLevel owner, int index, ValidationMethods validation)
         {
             _owner = owner;
             Index = index;
+            _validation = validation;
         }
 
         /// <summary>
@@ -103,7 +106,10 @@ namespace Perspex
 
             if (validationStatus != null)
             {
-                _owner.Validation(this, validationStatus);
+                if (validationStatus.Match(_validation))
+                {
+                    _owner.Validation(this, validationStatus);
+                }
             }
             else if (bindingError == null || bindingError.UseFallbackValue)
             {

src/Perspex.Base/PriorityLevel.cs

@@ -97,12 +97,13 @@ namespace Perspex
         /// Adds a binding.
         /// </summary>
         /// <param name="binding">The binding to add.</param>
+        /// <param name="validation">Validation settings for the binding.</param>
         /// <returns>A disposable used to remove the binding.</returns>
-        public IDisposable Add(IObservable<object> binding)
+        public IDisposable Add(IObservable<object> binding, ValidationMethods validation)
         {
             Contract.Requires<ArgumentNullException>(binding != null);
 
-            var entry = new PriorityBindingEntry(this, _nextIndex++);
+            var entry = new PriorityBindingEntry(this, _nextIndex++, validation);
             var node = Bindings.AddFirst(entry);
 
             entry.Start(binding);

src/Perspex.Base/PriorityValue.cs

@@ -77,12 +77,13 @@ namespace Perspex
         /// </summary>
         /// <param name="binding">The binding.</param>
         /// <param name="priority">The binding priority.</param>
+        /// <param name="validation">Validation settings for the binding.</param>
         /// <returns>
         /// A disposable that will remove the binding.
         /// </returns>
-        public IDisposable Add(IObservable<object> binding, int priority)
+        public IDisposable Add(IObservable<object> binding, int priority, ValidationMethods validation = ValidationMethods.None)
         {
-            return GetLevel(priority).Add(binding);
+            return GetLevel(priority).Add(binding, validation);
         }
 
         /// <summary>

tests/Perspex.Markup.Xaml.UnitTests/Data/BindingTests_TemplatedParent.cs

@@ -32,7 +32,8 @@ namespace Perspex.Markup.Xaml.UnitTests.Data
             target.Verify(x => x.Bind(
                 TextBox.TextProperty, 
                 It.IsAny<IObservable<object>>(), 
-                BindingPriority.TemplatedParent));
+                BindingPriority.TemplatedParent,
+                ValidationMethods.None));
         }
 
         [Fact]
@@ -52,7 +53,8 @@ namespace Perspex.Markup.Xaml.UnitTests.Data
             target.Verify(x => x.Bind(
                 TextBox.TextProperty,
                 It.IsAny<ISubject<object>>(),
-                BindingPriority.TemplatedParent));
+                BindingPriority.TemplatedParent,
+                ValidationMethods.None));
         }
 
         private Mock<IControl> CreateTarget(

tests/Perspex.Markup.Xaml.UnitTests/Data/BindingTests_Validation.cs

@@ -0,0 +1,112 @@
+using Perspex.Controls;
+using Perspex.Markup.Xaml.Data;
+using System;
+using System.Collections.Generic;
+using System.ComponentModel;
+using System.Linq;
+using System.Runtime.CompilerServices;
+using System.Text;
+using System.Threading.Tasks;
+using Xunit;
+
+namespace Perspex.Markup.Xaml.UnitTests.Data
+{
+    public class BindingTests_Validation
+    {
+
+        public class Data : INotifyPropertyChanged
+        {
+            private string mustbeNonEmpty;
+
+            public string MustBeNonEmpty
+            {
+                get { return mustbeNonEmpty; }
+                set
+                {
+                    if (string.IsNullOrEmpty(value))
+                    {
+                        throw new ArgumentException(nameof(value));
+                    }
+                    mustbeNonEmpty = value;
+                }
+            }
+
+            public event PropertyChangedEventHandler PropertyChanged;
+
+            private void NotifyPropertyChanged([CallerMemberName] string propertyName = "")
+            {
+                PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
+            }
+        }
+
+        [Fact]
+        public void Disabled_Validation_Should_Not_Trigger_Validation_Change_Direct()
+        {
+            var source = new Data { MustBeNonEmpty = "Test" };
+            var target = new TextBlock { DataContext = source };
+            var binding = new Binding
+            {
+                Path = nameof(source.MustBeNonEmpty),
+                Mode = Perspex.Data.BindingMode.TwoWay,
+                ValidationMethods = Perspex.Data.ValidationMethods.None
+            };
+            target.Bind(TextBlock.TextProperty, binding);
+            
+            target.Text = "";
+
+            Assert.Null(target.ValidationStatus);
+        }
+
+        [Fact]
+        public void Enabled_Validation_Should_Trigger_Validation_Change_Direct()
+        {
+            var source = new Data { MustBeNonEmpty = "Test" };
+            var target = new TextBlock { DataContext = source };
+            var binding = new Binding
+            {
+                Path = nameof(source.MustBeNonEmpty),
+                Mode = Perspex.Data.BindingMode.TwoWay,
+                ValidationMethods = Perspex.Data.ValidationMethods.All
+            };
+            target.Bind(TextBlock.TextProperty, binding);
+            
+            target.Text = "";
+            Assert.NotNull(target.ValidationStatus);
+        }
+
+        [Fact]
+        public void Disabled_Validation_Should_Not_Trigger_Validation_Change_Styled()
+        {
+            var source = new Data { MustBeNonEmpty = "Test" };
+            var target = new TextBlock { DataContext = source };
+            var binding = new Binding
+            {
+                Path = nameof(source.MustBeNonEmpty),
+                Mode = Perspex.Data.BindingMode.TwoWay,
+                ValidationMethods = Perspex.Data.ValidationMethods.None
+            };
+            target.Bind(Control.TagProperty, binding);
+
+            target.Tag = "";
+
+            Assert.Null(target.ValidationStatus);
+        }
+
+        [Fact]
+        public void Enabled_Validation_Should_Trigger_Validation_Change_Styled()
+        {
+            var source = new Data { MustBeNonEmpty = "Test" };
+            var target = new TextBlock { DataContext = source };
+            var binding = new Binding
+            {
+                Path = nameof(source.MustBeNonEmpty),
+                Mode = Perspex.Data.BindingMode.TwoWay,
+                ValidationMethods = Perspex.Data.ValidationMethods.All
+            };
+            target.Bind(Control.TagProperty, binding);
+
+            target.Tag = "";
+            Assert.NotNull(target.ValidationStatus);
+        }
+    }
+}

tests/Perspex.Markup.Xaml.UnitTests/Perspex.Markup.Xaml.UnitTests.csproj

@@ -94,6 +94,7 @@
   <ItemGroup>
     <Compile Include="Data\BindingTests_Source.cs" />
     <Compile Include="Data\BindingTests_ElementName.cs" />
+    <Compile Include="Data\BindingTests_Validation.cs" />
     <Compile Include="Data\MultiBindingTests.cs" />
     <Compile Include="Data\BindingTests_TemplatedParent.cs" />
     <Compile Include="Data\BindingTests.cs" />

tests/Perspex.Styling.UnitTests/SelectorTests_Child.cs

@@ -129,7 +129,7 @@ namespace Perspex.Styling.UnitTests
                 throw new NotImplementedException();
             }
 
-            public IDisposable Bind(PerspexProperty property, IObservable<object> source, BindingPriority priority)
+            public IDisposable Bind(PerspexProperty property, IObservable<object> source, BindingPriority priority, ValidationMethods validation)
             {
                 throw new NotImplementedException();
             }
@@ -139,7 +139,7 @@ namespace Perspex.Styling.UnitTests
                 throw new NotImplementedException();
             }
 
-            public IDisposable Bind<T>(PerspexProperty<T> property, IObservable<T> source, BindingPriority priority = BindingPriority.LocalValue)
+            public IDisposable Bind<T>(PerspexProperty<T> property, IObservable<T> source, BindingPriority priority = BindingPriority.LocalValue, ValidationMethods validation = ValidationMethods.None)
             {
                 throw new NotImplementedException();
             }

tests/Perspex.Styling.UnitTests/SelectorTests_Descendent.cs

@@ -160,7 +160,7 @@ namespace Perspex.Styling.UnitTests
                 throw new NotImplementedException();
             }
 
-            public IDisposable Bind(PerspexProperty property, IObservable<object> source, BindingPriority priority)
+            public IDisposable Bind(PerspexProperty property, IObservable<object> source, BindingPriority priority = BindingPriority.LocalValue, ValidationMethods validation = ValidationMethods.None)
             {
                 throw new NotImplementedException();
             }
@@ -170,7 +170,7 @@ namespace Perspex.Styling.UnitTests
                 throw new NotImplementedException();
             }
 
-            public IDisposable Bind<T>(PerspexProperty<T> property, IObservable<T> source, BindingPriority priority = BindingPriority.LocalValue)
+            public IDisposable Bind<T>(PerspexProperty<T> property, IObservable<T> source, BindingPriority priority = BindingPriority.LocalValue, ValidationMethods validation = ValidationMethods.None)
             {
                 throw new NotImplementedException();
             }

tests/Perspex.Styling.UnitTests/TestControlBase.cs

@@ -62,12 +62,12 @@ namespace Perspex.Styling.UnitTests
             throw new NotImplementedException();
         }
 
-        public IDisposable Bind(PerspexProperty property, IObservable<object> source, BindingPriority priority)
+        public IDisposable Bind(PerspexProperty property, IObservable<object> source, BindingPriority priority = BindingPriority.LocalValue, ValidationMethods validation = ValidationMethods.None)
         {
             throw new NotImplementedException();
         }
 
-        public IDisposable Bind<T>(PerspexProperty<T> property, IObservable<T> source, BindingPriority priority = BindingPriority.LocalValue)
+        public IDisposable Bind<T>(PerspexProperty<T> property, IObservable<T> source, BindingPriority priority = BindingPriority.LocalValue, ValidationMethods validation = ValidationMethods.None)
         {
             throw new NotImplementedException();
         }

tests/Perspex.Styling.UnitTests/TestTemplatedControl.cs

@@ -57,12 +57,12 @@ namespace Perspex.Styling.UnitTests
             throw new NotImplementedException();
         }
 
-        public IDisposable Bind(PerspexProperty property, IObservable<object> source, BindingPriority priority)
+        public IDisposable Bind(PerspexProperty property, IObservable<object> source, BindingPriority priority = BindingPriority.LocalValue, ValidationMethods validation = ValidationMethods.None)
         {
             throw new NotImplementedException();
         }
 
-        public IDisposable Bind<T>(PerspexProperty<T> property, IObservable<T> source, BindingPriority priority = BindingPriority.LocalValue)
+        public IDisposable Bind<T>(PerspexProperty<T> property, IObservable<T> source, BindingPriority priority = BindingPriority.LocalValue, ValidationMethods validation = ValidationMethods.None)
         {
             throw new NotImplementedException();
         }