maui-linux/Xamarin.Forms.Core.UnitTests/BindableObjectUnitTests.cs

using System;
using System.Globalization;
using NUnit.Framework;
using Xamarin.Forms.Internals;

namespace Xamarin.Forms.Core.UnitTests
{
	[TypeConverter (typeof(ToBarConverter))]
	internal class Bar
	{

	}

	internal class Baz
	{

	}

	internal class MockBindable
		: VisualElement
	{
		public static readonly BindableProperty TextProperty = BindableProperty.Create<MockBindable, string> (
			b => b.Text, "default", BindingMode.TwoWay);

		public string Text
		{
			get { return (string)GetValue (TextProperty); }
			set { SetValue (TextProperty, value); }
		}

		public string Foo { get; set; }

		public int TargetInt { get; set; }

		public static readonly BindableProperty BarProperty = 
			BindableProperty.Create<MockBindable, Bar> (w => w.Bar, default(Bar));

		public Bar Bar {
			get { return (Bar)GetValue (BarProperty); }
			set { SetValue (BarProperty, value); } 
		}

		public static readonly BindableProperty BazProperty = 
			BindableProperty.Create<MockBindable, Baz> (w => w.Baz, default(Baz));

		[TypeConverter (typeof (ToBazConverter))]
		public Baz Baz {
			get { return (Baz)GetValue (BazProperty); }
			set { SetValue (BazProperty, value); } 
		}

		public static readonly BindableProperty QuxProperty = 
			BindableProperty.Create<MockBindable, Baz> (w => w.Qux, default(Baz));

		public Baz Qux {
			get { return (Baz)GetValue (QuxProperty); }
			set { SetValue (QuxProperty, value); } 
		}
	}

	internal class ToBarConverter : TypeConverter
	{
		public override object ConvertFrom (System.Globalization.CultureInfo culture, object value)
		{
			return new Bar ();
		}
	}

	internal class ToBazConverter : TypeConverter
	{
		public override object ConvertFrom (System.Globalization.CultureInfo culture, object value)
		{
			return new Baz ();
		}
	}

	[TestFixture]
	public class BindableObjectUnitTests : BaseTestFixture
	{
		[SetUp]
		public void Setup()
		{
			Device.PlatformServices = new MockPlatformServices ();
		}

		[TearDown]
		public void TearDown()
		{
			Device.PlatformServices = null;
		}

		[Test]
		public void BindingContext()
		{
			var mock = new MockBindable();
			Assert.IsNull (mock.BindingContext);
			
			object obj = new object();
			mock.BindingContext = obj;
			Assert.AreSame (obj, mock.BindingContext);
		}

		[Test]
		public void BindingContextChangedEvent()
		{
			var mock = new MockBindable();
			mock.BindingContextChanged += (sender, args) => Assert.Pass();

			mock.BindingContext = new object();

			Assert.Fail ("The BindingContextChanged event was not fired.");
		}

		[Test]
		public void BindingContextChangedOnce()
		{
			var count = 0;

			var mock = new MockBindable();
			mock.BindingContextChanged += (sender, args) => ++count;

			mock.BindingContext = new object();
			Assert.AreEqual(count, 1);
		}

		class MockVMEquals {
			public string Key { get; set; }
			public string Text { get; set; }
			public override bool Equals(object obj)
			{
				var other = obj as MockVMEquals;
				if (other == null)
					return false;
				return Key == other.Key;
			}

			public override int GetHashCode()
			{
				return base.GetHashCode();
			}
		}

		[Test]
		//https://bugzilla.xamarin.com/show_bug.cgi?id=59507
		public void BindingContextChangedCompareReferences()
		{
			var mock = new MockBindable();
			mock.BindingContext = new MockVMEquals { Key = "Foo", Text = "Foo" };
			mock.BindingContextChanged += (sender, args) => Assert.Pass();

			mock.BindingContext = new MockVMEquals { Key = "Foo", Text = "Bar" };

			Assert.Fail("The BindingContextChanged event was not fired.");
		}

		[Test]
		public void ParentAndChildBindingContextChanged()
		{
			int parentCount = 0, childCount = 0;

			var didNotChange = " BindingContext did not change.";
			var changedMoreThanOnce = " BindingContext changed more than once.";
			var changedWhenNoChange = " BindingContext was changed when there was no change in context.";

			var parent = new MockBindable();
			parent.BindingContextChanged += (sender, args) => { ++parentCount; };

			var child = new MockBindable();
			child.BindingContextChanged += (sender, args) => { ++childCount; };

			child.Parent = parent;
			Assert.AreEqual(parentCount, 0, "Parent BindingContext was changed while parenting a child.");
			Assert.AreEqual(childCount, 0, "Child" + changedWhenNoChange);

			child.BindingContext = new object(); // set manually
			Assert.GreaterOrEqual(childCount, 1, "Child" + didNotChange);
			Assert.AreEqual(childCount, 1, "Child" + changedMoreThanOnce);
			Assert.AreEqual(parentCount, 0, "Parent" + changedWhenNoChange);

			parent.BindingContext = new object();
			Assert.GreaterOrEqual(parentCount, 1, "Parent" + didNotChange);
			Assert.AreEqual(parentCount, 1, "Parent" + changedMoreThanOnce);
			Assert.AreEqual(childCount, 1, "Child" + changedWhenNoChange);

			child.BindingContext = new object();
			Assert.GreaterOrEqual(childCount, 2, "Child" + didNotChange);
			Assert.AreEqual(childCount, 2, "Child" + changedMoreThanOnce);
			Assert.AreEqual(parentCount, 1, "Parent" + changedWhenNoChange);
		}

		[Test]
		public void ParentSetOnNullChildBindingContext()
		{
			var parent = new MockBindable();

			var child = new MockBindable();
			child.BindingContextChanged += (sender, args) => { Assert.Fail("Child BindingContext was changed when there was no change in context."); };

			child.Parent = parent; // this should not trigger binding context change on child since there is no change
			parent.BindingContext = new object();
			parent.BindingContext = new object();
		}

		[Test]
		public void ParentSetOnNonNullChildBindingContext()
		{
			var count = 0;

			var parent = new MockBindable();
			parent.BindingContextChanged += (sender, args) => { ++count; };

			var child = new MockBindable();
			child.BindingContextChanged += (sender, args) => { ++count; };

			child.BindingContext = new object(); // set manually
			Assert.AreEqual(count, 1);

			child.Parent = parent; // this should not trigger binding context change because child binding was set manually
			Assert.AreEqual(count, 1);

			parent.BindingContext = new object();
			Assert.AreEqual(count, 2);

			child.BindingContext = new object();
			Assert.AreEqual(count, 3);
		}

		[Test]
		[Description ("When the BindingContext changes, any bindings should be immediately applied.")]
		public void BindingContextChangedBindingsApplied()
		{
			var mock = new MockBindable();
			mock.SetBinding (MockBindable.TextProperty, new Binding ("."));
			mock.BindingContext = "Test";

			Assert.AreEqual ("Test", mock.GetValue (MockBindable.TextProperty));

			mock.BindingContext = "Testing";

			Assert.AreEqual ("Testing", mock.GetValue (MockBindable.TextProperty),
				"Bindings were not reapplied to the new binding context");
		}

		[Test]
		[Description ("When the BindingContext changes, the new context needs to listen for updates.")]
		public void BindingContextChangedBindingsListening()
		{
			var mock = new MockBindable();
			mock.SetBinding (MockBindable.TextProperty, new Binding ("Text"));

			var vm = new MockViewModel();
			mock.BindingContext = vm;

			mock.BindingContext = (vm = new MockViewModel());

			vm.Text = "test";

			Assert.AreEqual ("test", mock.GetValue (MockBindable.TextProperty),
				"The new ViewModel was not being listened to after being set");
		}

		[Test]
		[Description ("When an INPC implementer is unset as the BindingContext, its changes shouldn't be listened to any further.")]
		public void BindingContextUnsetStopsListening()
		{
			var mock = new MockBindable();
			mock.SetBinding (MockBindable.TextProperty, new Binding ("Text"));

			var vm = new MockViewModel();
			mock.BindingContext = vm;

			mock.BindingContext = null;

			vm.Text = "test";

			Assert.IsNull (mock.GetValue (Entry.TextProperty), "ViewModel was still being listened to after set to null");
		}

		[Test]
		public void PropertyChanging()
		{
			var mock = new MockBindable();
			mock.PropertyChanging += (sender, args) => {
				Assert.AreEqual (MockBindable.TextProperty.PropertyName, args.PropertyName);
				Assert.AreEqual (MockBindable.TextProperty.DefaultValue, mock.GetValue (MockBindable.TextProperty));
				Assert.Pass();
			};

			mock.SetValue (MockBindable.TextProperty, "foo");

			Assert.Fail ("The PropertyChanging event was not fired.");
		}

		[Test]
		public void PropertyChangingSameValue()
		{
			const string value = "foo";

			var mock = new MockBindable();
			mock.SetValue (MockBindable.TextProperty, value);
			mock.PropertyChanging += (s,e) => Assert.Fail();

			mock.SetValue (MockBindable.TextProperty, value);

			Assert.Pass();
		}

		[Test]
		public void PropertyChangingDefaultValue()
		{
			var prop = BindableProperty.Create<MockBindable, string> (w => w.Foo, "DefaultValue");

			var mock = new MockBindable();
			mock.PropertyChanging += (s,e) => Assert.Fail();
			mock.SetValue (prop, prop.DefaultValue);

			Assert.Pass();
		}

		[Test]
		public void PropertyChanged()
		{
			const string value = "foo";

			var mock = new MockBindable();
			mock.PropertyChanged += (sender, args) => {
				Assert.AreEqual (MockBindable.TextProperty.PropertyName, args.PropertyName);
				Assert.AreEqual (value, mock.GetValue (MockBindable.TextProperty));
				Assert.Pass();
			};

			mock.SetValue (MockBindable.TextProperty, value);
			
			Assert.Fail ("The PropertyChanged event was not fired.");
		}

		[Test]
		public void PropertyChangedSameValue()
		{
			const string value = "foo";

			var mock = new MockBindable();
			mock.SetValue (MockBindable.TextProperty, value);
			mock.PropertyChanged += (s,e) => Assert.Fail();

			mock.SetValue (MockBindable.TextProperty, value);

			Assert.Pass();
		}

		[Test]
		public void PropertyChangedDefaultValue()
		{
			var prop = BindableProperty.Create<MockBindable, string> (w => w.Foo, "DefaultValue");

			var mock = new MockBindable();
			mock.PropertyChanged += (s,e) => Assert.Fail();
		
			mock.SetValue (prop, prop.DefaultValue);

			Assert.Pass();
		}

		[Test]
		public void GetSetValue()
		{
			const string value = "foo";
			var mock = new MockBindable();
			mock.SetValue (MockBindable.TextProperty, value);

			Assert.AreEqual (value, mock.GetValue (MockBindable.TextProperty));
		}

		[Test]
		public void GetValueDefault()
		{
			var nulldefault = BindableProperty.Create<MockBindable, string> (w => w.Foo, null);
			TestGetValueDefault (nulldefault);

			var foodefault = BindableProperty.Create<MockBindable, string> (w => w.Foo, "Foo");
			TestGetValueDefault (foodefault);
		}

		void TestGetValueDefault (BindableProperty property)
		{
			var mock = new MockBindable();
			object value = mock.GetValue (property);
			Assert.AreEqual (property.DefaultValue, value);
		}

		[Test]
		public void SetValueInvalid()
		{
			var mock = new MockBindable();
			Assert.Throws<ArgumentNullException> (() => mock.SetValue ((BindableProperty)null, "null"));
		}

		[Test]
		public void GetValueInvalid()
		{
			var mock = new MockBindable();
			Assert.Throws<ArgumentNullException> (() => mock.GetValue (null));
		}

		[Test]
		public void ClearValueInvalid()
		{
			var mock = new MockBindable();
			Assert.Throws<ArgumentNullException> (() => mock.ClearValue ((BindableProperty)null));
		}

		[Test]
		public void ClearValue()
		{
			const string value = "foo";
			var mock = new MockBindable();
			mock.SetValue (MockBindable.TextProperty, value);
			Assert.AreEqual (value, mock.GetValue (MockBindable.TextProperty));

			mock.ClearValue (MockBindable.TextProperty);
			TestGetValueDefault (MockBindable.TextProperty);
		}

		[Test]
		public void ClearValueTriggersINPC ()
		{
			var bindable = new MockBindable ();
			bool changingfired = false;
			bool changedfired = false;
			bool changingdelegatefired = false;
			bool changeddelegatefired = false;
			var property = BindableProperty.Create ("Foo", typeof(string), typeof(MockBindable), "foo", 
				propertyChanged: (b, o, n) => changeddelegatefired = true,
				propertyChanging: (b, o, n) => changingdelegatefired = true
			);
			bindable.PropertyChanged += (sender, e) => { changedfired |= e.PropertyName == "Foo"; };
			bindable.PropertyChanging += (sender, e) => { changingfired |= e.PropertyName == "Foo"; };

			bindable.SetValue (property, "foobar");
			changingfired = changedfired = changeddelegatefired = changingdelegatefired = false;

			bindable.ClearValue (property);
			Assert.True (changingfired);
			Assert.True (changedfired);
			Assert.True (changingdelegatefired);
			Assert.True (changeddelegatefired);
		}

		[Test]
		public void ClearValueDoesNotTriggersINPCOnSameValues ()
		{
			var bindable = new MockBindable ();
			bool changingfired = false;
			bool changedfired = false;
			bool changingdelegatefired = false;
			bool changeddelegatefired = false;
			var property = BindableProperty.Create ("Foo", typeof(string), typeof(MockBindable), "foo", 
				propertyChanged: (b, o, n) => changeddelegatefired = true,
				propertyChanging: (b, o, n) => changingdelegatefired = true
			);
			bindable.PropertyChanged += (sender, e) => { changedfired |= e.PropertyName == "Foo"; };
			bindable.PropertyChanging += (sender, e) => { changingfired |= e.PropertyName == "Foo"; };

			bindable.SetValue (property, "foobar");
			bindable.SetValue (property, "foo");
			changingfired = changedfired = changeddelegatefired = changingdelegatefired = false;

			bindable.ClearValue (property);
			Assert.False (changingfired);
			Assert.False (changedfired);
			Assert.False (changingdelegatefired);
			Assert.False (changeddelegatefired);
		}

		[Test]
		public void SetBindingInvalid()
		{
			var mock = new MockBindable();
			Assert.Throws<ArgumentNullException> (() => mock.SetBinding (null, new Binding (".")));
			Assert.Throws<ArgumentNullException> (() => mock.SetBinding (MockBindable.TextProperty, null));
		}

		[Test]
		public void RemoveUnaddedBinding()
		{
			var mock = new MockBindable();
			Assert.That (() => mock.RemoveBinding (MockBindable.TextProperty), Throws.Nothing);
		}

		[Test]
		public void RemoveBindingInvalid()
		{
			var mock = new MockBindable();
			Assert.Throws<ArgumentNullException> (() => mock.RemoveBinding (null));
		}

		[Test]
		public void RemovedBindingDoesNotUpdate()
		{
			const string newvalue = "New Value";
			var viewmodel = new MockViewModel {
				Text = "Foo"
			};

			var binding = new Binding ("Text");

			var bindable = new MockBindable();
			bindable.BindingContext = viewmodel;
			bindable.SetBinding (MockBindable.TextProperty, binding);

			string original = (string)bindable.GetValue (MockBindable.TextProperty);

			bindable.RemoveBinding (MockBindable.TextProperty);

			viewmodel.Text = newvalue;
			Assert.AreEqual (original, bindable.GetValue (MockBindable.TextProperty),
				"Property updated from a removed binding");
		}

		[Test]
		public void CoerceValue()
		{
			var property = BindableProperty.Create<MockBindable, string> (w => w.Foo, null,
				coerceValue: (bo, o) => o.ToUpper());

			const string value = "value";
			var mock = new MockBindable();
			mock.SetValue (property, value);
			Assert.AreEqual (value.ToUpper(), mock.GetValue (property));
		}

		[Test]
		public void ValidateValue()
		{
			var property = BindableProperty.Create<MockBindable, string> (w => w.Foo, null,
				validateValue: (b, v) => false);

			var mock = new MockBindable();
			Assert.Throws<ArgumentException> (() => mock.SetValue (property, null));
		}

		[Test]
		public void BindablePropertyChanged()
		{
			bool changed = false;

			string oldv = "bar";
			string newv = "foo";

			var property = BindableProperty.Create<MockBindable, string> (w => w.Foo, oldv,
				propertyChanged: (b, ov, nv) => {
					Assert.AreSame (oldv, ov);
					Assert.AreSame (newv, nv);
					changed = true;
				});

			var mock = new MockBindable();
			mock.SetValue (property, newv);

			Assert.IsTrue (changed, "PropertyChanged was not called");
		}

		[Test]
		public void RecursiveChange ()
		{
			bool changedA1 = false, changedA2 = false, changedB1 = false, changedB2 = false;

			var mock = new MockBindable ();
			mock.PropertyChanged += (sender, args) => {
				if (!changedA1) {
					Assert.AreEqual ("1", mock.GetValue (MockBindable.TextProperty));
					Assert.IsFalse (changedA2);
					Assert.IsFalse (changedB1);
					Assert.IsFalse (changedB2);
					mock.SetValue (MockBindable.TextProperty, "2");
					changedA1 = true;
				} else {
					Assert.AreEqual ("2", mock.GetValue (MockBindable.TextProperty));
					Assert.IsFalse (changedA2);
					Assert.IsTrue (changedB1);
					Assert.IsFalse (changedB2);
					changedA2 = true;
				}
			};
			mock.PropertyChanged += (sender, args) => {
				if (!changedB1) {
					Assert.AreEqual ("1", mock.GetValue (MockBindable.TextProperty));
					Assert.IsTrue (changedA1);
					Assert.IsFalse (changedA2);
					Assert.IsFalse (changedB2);
					changedB1 = true;
				} else {
					Assert.AreEqual ("2", mock.GetValue (MockBindable.TextProperty));
					Assert.IsTrue (changedA1);
					Assert.IsTrue (changedA2);
					Assert.IsFalse (changedB2);
					changedB2 = true;
				}
			};
			mock.SetValue (MockBindable.TextProperty, "1");
			Assert.AreEqual ("2", mock.GetValue (MockBindable.TextProperty));
			Assert.IsTrue (changedA1);
			Assert.IsTrue (changedA2);
			Assert.IsTrue (changedB1);
			Assert.IsTrue (changedB2);
		}

		[Test]
		public void RaiseOnEqual()
		{
			string foo = "foo";
			var mock = new MockBindable();
			mock.SetValue (MockBindable.TextProperty, foo);

			bool changing = false;
			mock.PropertyChanging += (o, e) => {
				Assert.That (e.PropertyName, Is.EqualTo (MockBindable.TextProperty.PropertyName));
				changing = true;
			};

			bool changed = true;
			mock.PropertyChanged += (o, e) => {
				Assert.That (e.PropertyName, Is.EqualTo (MockBindable.TextProperty.PropertyName));
				changed = true;
			};

			mock.SetValueCore (MockBindable.TextProperty, foo, 
				SetValueFlags.ClearOneWayBindings | SetValueFlags.ClearDynamicResource | SetValueFlags.RaiseOnEqual);

			Assert.That (changing, Is.True, "PropertyChanging event did not fire");
			Assert.That (changed, Is.True, "PropertyChanged event did not fire");
		}

		[Test]
		public void BindingContextGetter ()
		{
			var label = new Label ();
			var view = new StackLayout { Children = {label} };

			view.BindingContext = new {item0 = "Foo", item1 = "Bar"};
			label.SetBinding (BindableObject.BindingContextProperty, "item0");
			label.SetBinding (Label.TextProperty, Binding.SelfPath);

			Assert.AreSame (label.BindingContext, label.GetValue (BindableObject.BindingContextProperty));
		}

		[Test]
		public void BoundBindingContextUpdate ()
		{
			var label = new Label ();
			var view = new StackLayout { Children = {label} };
			var vm = new MockViewModel { Text = "FooBar" };

			view.BindingContext = vm;
			label.SetBinding (BindableObject.BindingContextProperty, "Text");
			label.SetBinding (Label.TextProperty, Binding.SelfPath);

			Assert.AreEqual ("FooBar", label.BindingContext);

			vm.Text = "Baz";
			Assert.AreEqual ("Baz", label.BindingContext);
		}

		[Test]
		public void BoundBindingContextChange ()
		{
			var label = new Label ();
			var view = new StackLayout { Children = {label} };

			view.BindingContext = new MockViewModel { Text = "FooBar" };;
			label.SetBinding (BindableObject.BindingContextProperty, "Text");
			label.SetBinding (Label.TextProperty, Binding.SelfPath);

			Assert.AreEqual ("FooBar", label.BindingContext);

			view.BindingContext = new MockViewModel { Text = "Baz" };;
			Assert.AreEqual ("Baz", label.BindingContext);
		}

		[Test]
		public void TestReadOnly ()
		{
			var bindablePropertyKey = BindableProperty.CreateReadOnly<MockBindable, string> (w => w.Foo, "DefaultValue");
			var bindableProperty = bindablePropertyKey.BindableProperty;

			var bindable = new MockBindable ();
			Assert.AreEqual ("DefaultValue", bindable.GetValue (bindableProperty));

			bindable.SetValue (bindablePropertyKey, "Bar");
			Assert.AreEqual ("Bar", bindable.GetValue (bindableProperty));

			Assert.Throws<InvalidOperationException> (() => bindable.SetValue (bindableProperty, "Baz"));
			Assert.AreEqual ("Bar", bindable.GetValue (bindableProperty));

			Assert.Throws<InvalidOperationException> (() => bindable.ClearValue (bindableProperty));

			bindable.ClearValue (bindablePropertyKey);
			Assert.AreEqual ("DefaultValue", bindable.GetValue (bindableProperty));
		}

		[Test]
		public void TestBindingTwoWayOnReadOnly ()
		{
			var bindablePropertyKey = BindableProperty.CreateReadOnly<MockBindable, string> (w => w.Foo, "DefaultValue", BindingMode.OneWayToSource);
			var bindableProperty = bindablePropertyKey.BindableProperty;

			var bindable = new MockBindable ();
			var vm = new MockViewModel ();

			bindable.SetBinding (bindableProperty, new Binding ("Text", BindingMode.TwoWay));
			Assert.DoesNotThrow (() => bindable.BindingContext = vm);

			Assert.AreEqual ("DefaultValue", bindable.GetValue (bindableProperty));
		}

		[Test]
		public void DefaultValueCreator ()
		{
			int invoked = 0;
			object defaultValue = new object ();
			var bindableProperty = BindableProperty.Create ("Foo", typeof(object), typeof(MockBindable), defaultValue, defaultValueCreator: o => {
				invoked++;
				return new object ();
			});
			var bindable = new MockBindable ();

			Assert.AreSame (defaultValue, bindableProperty.DefaultValue);
			var newvalue = bindable.GetValue (bindableProperty);
			Assert.AreNotSame (defaultValue, newvalue);
			Assert.NotNull (newvalue);
			Assert.AreEqual (1, invoked);
		}

		[Test]
		public void DefaultValueCreatorIsInvokedOnlyAtFirstTime ()
		{
			int invoked = 0;
			var bindableProperty = BindableProperty.Create ("Foo", typeof(object), typeof(MockBindable), null, defaultValueCreator: o => {
				invoked++;
				return new object ();
			});
			var bindable = new MockBindable ();

			var value0 = bindable.GetValue (bindableProperty);
			var value1 = bindable.GetValue (bindableProperty);
			Assert.NotNull (value0);
			Assert.NotNull (value1);
			Assert.AreSame (value0, value1);
			Assert.AreEqual (1, invoked);
		}

		[Test]
		public void DefaultValueCreatorNotSharedAccrossInstances ()
		{
			int invoked = 0;
			var bindableProperty = BindableProperty.Create ("Foo", typeof(object), typeof(MockBindable), null, defaultValueCreator: o=> {
				invoked++;
				return new object ();
			});
			var bindable0 = new MockBindable ();
			var bindable1 = new MockBindable ();
			var value0 = bindable0.GetValue (bindableProperty);
			var value1 = bindable1.GetValue (bindableProperty);

			Assert.AreNotSame (value0, value1);
			Assert.AreEqual (2, invoked);
		}

		[Test]
		public void DefaultValueCreatorInvokedAfterClearValue ()
		{
			int invoked = 0;
			var bindableProperty = BindableProperty.Create ("Foo", typeof(object), typeof(MockBindable), null, defaultValueCreator: o => {
				invoked++;
				return new object ();
			});
			var bindable = new MockBindable ();

			Assert.AreEqual (0, invoked);

			var value0 = bindable.GetValue (bindableProperty);
			Assert.NotNull (value0);
			Assert.AreEqual (1, invoked);
			bindable.ClearValue (bindableProperty);

			var value1 = bindable.GetValue (bindableProperty);
			Assert.NotNull (value1);
			Assert.AreEqual (2, invoked);
			Assert.AreNotSame (value0, value1);
		}

		[Test]
		public void DefaultValueCreatorOnlyInvokedOnGetValue ()
		{
			int invoked = 0;
			var bindableProperty = BindableProperty.Create ("Foo", typeof(object), typeof(MockBindable), null, defaultValueCreator: o => {
				invoked++;
				return new object ();
			});
			var bindable = new MockBindable ();

			Assert.AreEqual (0, invoked);

			var newvalue = bindable.GetValue (bindableProperty);
			Assert.NotNull (newvalue);
			Assert.AreEqual (1, invoked);
		}

		[Test]
		public void DefaultValueCreatorDoesNotTriggerINPC ()
		{
			int invoked = 0;
			int propertychanged = 0;
			int changedfired = 0;
			var bindableProperty = BindableProperty.Create ("Foo", typeof(object), typeof(MockBindable), null, 
				propertyChanged: (bindable,oldvalue,newvalue) =>{
					propertychanged ++;
				},
				defaultValueCreator: o => {
					invoked++;
					return new object ();
				});

			var bp = new MockBindable ();
			bp.PropertyChanged += (sender, e) => {
				if (e.PropertyName == "Foo")
					changedfired++;
			};
			var value0 = bp.GetValue (bindableProperty);
			Assert.NotNull (value0);
			Assert.AreEqual (1, invoked);
			Assert.AreEqual (0, propertychanged);
			Assert.AreEqual (0, changedfired);

		}

		[Test]
		public void StyleValueIsOverridenByValue ()
		{
			var label = new Label ();
			label.SetValue (Label.TextProperty, "Foo", true);
			Assert.AreEqual ("Foo", label.Text);

			label.SetValue (Label.TextProperty, "Bar");
			Assert.AreEqual ("Bar", label.Text);
		}

		[Test]
		public void StyleBindingIsOverridenByValue ()
		{
			var label = new Label ();
			label.SetBinding (Label.TextProperty, new Binding ("foo"), true);
			label.BindingContext = new {foo = "Foo"};
			Assert.AreEqual ("Foo", label.Text);

			label.SetValue (Label.TextProperty, "Bar");
			Assert.AreEqual ("Bar", label.Text);
		}

		[Test]
		public void StyleDynResourceIsOverridenByValue ()
		{
			var label = new Label ();
			label.SetDynamicResource (Label.TextProperty, "foo", true);
			label.Resources = new ResourceDictionary {
				{"foo", "Foo"}
			};
			Assert.AreEqual ("Foo", label.Text);

			label.SetValue (Label.TextProperty, "Bar");
			Assert.AreEqual ("Bar", label.Text);
		}

		[Test]
		public void StyleValueIsOverridenByBinding ()
		{
			var label = new Label ();
			label.BindingContext = new {foo = "Foo", bar = "Bar"};
			label.SetValue (Label.TextProperty, "Foo", true);
			Assert.AreEqual ("Foo", label.Text);

			label.SetBinding (Label.TextProperty, "bar");
			Assert.AreEqual ("Bar", label.Text);
		}

		[Test]
		public void StyleBindingIsOverridenByBinding ()
		{
			var label = new Label ();
			label.BindingContext = new {foo = "Foo", bar = "Bar"};
			label.SetBinding (Label.TextProperty, new Binding ("foo"), true);
			Assert.AreEqual ("Foo", label.Text);

			label.SetBinding (Label.TextProperty, "bar");
			Assert.AreEqual ("Bar", label.Text);
		}

		[Test]
		public void StyleDynResourceIsOverridenByBinding ()
		{
			var label = new Label ();
			label.BindingContext = new {foo = "Foo", bar = "Bar"};
			label.SetDynamicResource (Label.TextProperty, "foo", true);
			label.Resources = new ResourceDictionary {
				{"foo", "Foo"},
			};
			Assert.AreEqual ("Foo", label.Text);

			label.SetBinding (Label.TextProperty, "bar");
			Assert.AreEqual ("Bar", label.Text);
		}

		[Test]
		public void StyleValueIsOverridenByDynResource ()
		{
			var label = new Label ();
			label.Resources = new ResourceDictionary {
				{"foo", "Foo"},
				{"bar", "Bar"}
			};
			label.BindingContext = new {foo = "Foo", bar = "Bar"};
			label.SetValue (Label.TextProperty, "Foo", true);
			Assert.AreEqual ("Foo", label.Text);

			label.SetDynamicResource (Label.TextProperty, "bar");
			Assert.AreEqual ("Bar", label.Text);
		}

		[Test]
		public void StyleBindingIsOverridenByDynResource ()
		{
			var label = new Label ();
			label.Resources = new ResourceDictionary {
				{"foo", "Foo"},
				{"bar", "Bar"}
			};
			label.BindingContext = new {foo = "Foo", bar = "Bar"};
			label.SetBinding (Label.TextProperty, new Binding ("foo"), true);
			Assert.AreEqual ("Foo", label.Text);

			label.SetDynamicResource (Label.TextProperty, "bar");
			Assert.AreEqual ("Bar", label.Text);
		}

		[Test]
		public void StyleDynResourceIsOverridenByDynResource ()
		{
			var label = new Label ();
			label.Resources = new ResourceDictionary {
				{"foo", "Foo"},
				{"bar", "Bar"}
			};
			label.BindingContext = new {foo = "Foo", bar = "Bar"};
			label.SetDynamicResource (Label.TextProperty, "foo", true);

			Assert.AreEqual ("Foo", label.Text);

			label.SetDynamicResource (Label.TextProperty, "bar");
			Assert.AreEqual ("Bar", label.Text);
		}

		[Test]
		public void ValueIsPreservedOnStyleValue ()
		{
			var label = new Label ();
			label.SetValue (Label.TextProperty, "Foo");
			Assert.AreEqual ("Foo", label.Text);

			label.SetValue (Label.TextProperty, "Bar", true);
			Assert.AreEqual ("Foo", label.Text);
		}
		[Test]
		public void BindingIsPreservedOnStyleValue ()
		{
			var label = new Label ();
			label.SetBinding (Label.TextProperty, new Binding ("foo"));
			label.BindingContext = new {foo = "Foo"};
			Assert.AreEqual ("Foo", label.Text);

			label.SetValue (Label.TextProperty, "Bar", true);
			Assert.AreEqual ("Foo", label.Text);
		}
		[Test]
		public void DynResourceIsPreservedOnStyleValue ()
		{
			var label = new Label ();
			label.SetDynamicResource (Label.TextProperty, "foo");
			label.Resources = new ResourceDictionary {
				{"foo", "Foo"}
			};
			Assert.AreEqual ("Foo", label.Text);

			label.SetValue (Label.TextProperty, "Bar", true);
			Assert.AreEqual ("Foo", label.Text);
		}

		[Test]
		public void ValueIsPreservedOnStyleBinding ()
		{
			var label = new Label ();
			label.BindingContext = new {foo = "Foo", bar = "Bar"};
			label.SetValue (Label.TextProperty, "Foo");
			Assert.AreEqual ("Foo", label.Text);

			label.SetBinding (Label.TextProperty, new Binding ("bar"), true);
			Assert.AreEqual ("Foo", label.Text);
		}

		[Test]
		public void BindingIsPreservedOnStyleBinding ()
		{
			var label = new Label ();
			label.BindingContext = new {foo = "Foo", bar = "Bar"};
			label.SetBinding (Label.TextProperty, new Binding ("foo"));
			Assert.AreEqual ("Foo", label.Text);

			label.SetBinding (Label.TextProperty, new Binding ("bar"), true);
			Assert.AreEqual ("Foo", label.Text);
		}

		[Test]
		public void DynResourceIsPreservedOnStyleBinding ()
		{
			var label = new Label ();
			label.BindingContext = new {foo = "Foo", bar = "Bar"};
			label.SetDynamicResource (Label.TextProperty, "foo");
			label.Resources = new ResourceDictionary {
				{"foo", "Foo"},
			};
			Assert.AreEqual ("Foo", label.Text);

			label.SetBinding (Label.TextProperty, new Binding ("bar"), true);
			Assert.AreEqual ("Foo", label.Text);
		}

		[Test]
		public void ValueIsPreservedOnStyleDynResource ()
		{
			var label = new Label ();
			label.Resources = new ResourceDictionary {
				{"foo", "Foo"},
				{"bar", "Bar"}
			};
			label.BindingContext = new {foo = "Foo", bar = "Bar"};
			label.SetValue (Label.TextProperty, "Foo");
			Assert.AreEqual ("Foo", label.Text);

			label.SetDynamicResource (Label.TextProperty, "bar", true);
			Assert.AreEqual ("Foo", label.Text);
		}

		[Test]
		public void BindingIsPreservedOnStyleDynResource ()
		{
			var label = new Label ();
			label.Resources = new ResourceDictionary {
				{"foo", "Foo"},
				{"bar", "Bar"}
			};
			label.BindingContext = new {foo = "Foo", bar = "Bar"};
			label.SetBinding (Label.TextProperty, new Binding ("foo"));
			Assert.AreEqual ("Foo", label.Text);

			label.SetDynamicResource (Label.TextProperty, "bar", true);
			Assert.AreEqual ("Foo", label.Text);
		}

		[Test]
		public void DynResourceIsPreservedOnStyleDynResource ()
		{
			var label = new Label ();
			label.Resources = new ResourceDictionary {
				{"foo", "Foo"},
				{"bar", "Bar"}
			};
			label.BindingContext = new {foo = "Foo", bar = "Bar"};
			label.SetDynamicResource (Label.TextProperty, "foo");

			Assert.AreEqual ("Foo", label.Text);

			label.SetDynamicResource (Label.TextProperty, "bar", true);
			Assert.AreEqual ("Foo", label.Text);
		}

		[Test]
		public void StyleValueIsOverridenByStyleValue ()
		{
			var label = new Label ();
			label.SetValue (Label.TextProperty, "Foo", true);
			Assert.AreEqual ("Foo", label.Text);

			label.SetValue (Label.TextProperty, "Bar", true);
			Assert.AreEqual ("Bar", label.Text);
		}

		[Test]
		public void StyleBindingIsOverridenByStyleValue ()
		{
			var label = new Label ();
			label.SetBinding (Label.TextProperty, new Binding ("foo"), true);
			label.BindingContext = new {foo = "Foo"};
			Assert.AreEqual ("Foo", label.Text);

			label.SetValue (Label.TextProperty, "Bar", true);
			Assert.AreEqual ("Bar", label.Text);
		}

		[Test]
		public void StyleDynResourceIsOverridenByStyleValue ()
		{
			var label = new Label ();
			label.SetDynamicResource (Label.TextProperty, "foo", true);
			label.Resources = new ResourceDictionary {
				{"foo", "Foo"}
			};
			Assert.AreEqual ("Foo", label.Text);

			label.SetValue (Label.TextProperty, "Bar", true);
			Assert.AreEqual ("Bar", label.Text);
		}

		[Test]
		public void StyleValueIsOverridenByStyleBinding ()
		{
			var label = new Label ();
			label.BindingContext = new {foo = "Foo", bar = "Bar"};
			label.SetValue (Label.TextProperty, "Foo", true);
			Assert.AreEqual ("Foo", label.Text);

			label.SetBinding (Label.TextProperty, new Binding("bar"), true);
			Assert.AreEqual ("Bar", label.Text);
		}

		[Test]
		public void StyleBindingIsOverridenByStyleBinding ()
		{
			var label = new Label ();
			label.BindingContext = new {foo = "Foo", bar = "Bar"};
			label.SetBinding (Label.TextProperty, new Binding ("foo"), true);
			Assert.AreEqual ("Foo", label.Text);

			label.SetBinding (Label.TextProperty, new Binding("bar"), true);
			Assert.AreEqual ("Bar", label.Text);
		}

		[Test]
		public void StyleDynResourceIsOverridenByStyleBinding ()
		{
			var label = new Label ();
			label.BindingContext = new {foo = "Foo", bar = "Bar"};
			label.SetDynamicResource (Label.TextProperty, "foo", true);
			label.Resources = new ResourceDictionary {
				{"foo", "Foo"},
			};
			Assert.AreEqual ("Foo", label.Text);

			label.SetBinding (Label.TextProperty, new Binding("bar"), true);
			Assert.AreEqual ("Bar", label.Text);
		}

		[Test]
		public void StyleValueIsOverridenByStyleDynResource ()
		{
			var label = new Label ();
			label.Resources = new ResourceDictionary {
				{"foo", "Foo"},
				{"bar", "Bar"}
			};
			label.BindingContext = new {foo = "Foo", bar = "Bar"};
			label.SetValue (Label.TextProperty, "Foo", true);
			Assert.AreEqual ("Foo", label.Text);

			label.SetDynamicResource (Label.TextProperty, "bar", true);
			Assert.AreEqual ("Bar", label.Text);
		}

		[Test]
		public void StyleBindingIsOverridenByStyleDynResource ()
		{
			var label = new Label ();
			label.Resources = new ResourceDictionary {
				{"foo", "Foo"},
				{"bar", "Bar"}
			};
			label.BindingContext = new {foo = "Foo", bar = "Bar"};
			label.SetBinding (Label.TextProperty, new Binding ("foo"), true);
			Assert.AreEqual ("Foo", label.Text);

			label.SetDynamicResource (Label.TextProperty, "bar", true);
			Assert.AreEqual ("Bar", label.Text);
		}

		[Test]
		public void StyleDynResourceIsOverridenByStyleDynResource ()
		{
			var label = new Label ();
			label.Resources = new ResourceDictionary {
				{"foo", "Foo"},
				{"bar", "Bar"}
			};
			label.BindingContext = new {foo = "Foo", bar = "Bar"};
			label.SetDynamicResource (Label.TextProperty, "foo", true);

			Assert.AreEqual ("Foo", label.Text);

			label.SetDynamicResource (Label.TextProperty, "bar", true);
			Assert.AreEqual ("Bar", label.Text);
		}

		[Test]
		public void SetValueCoreImplicitelyCastBasicType ()
		{
			var prop = BindableProperty.Create ("Foo", typeof(int), typeof(MockBindable), 0);
			var bindable = new MockBindable ();

			Assert.DoesNotThrow (() => bindable.SetValue (prop, (object)(short)42));
			Assert.AreEqual (42, bindable.GetValue (prop));

			bindable.SetValue (prop, (object)(long)-42);
			Assert.AreNotEqual (-42, bindable.GetValue (prop));
		}

		class CastFromString
		{
			public string Result { get; private set; }
			public static implicit operator CastFromString (string source)
			{
				var o = new CastFromString ();
				o.Result = source;
				return o;
			}
		}

		[Test]
		public void SetValueCoreInvokesOpImplicitOnPropertyType ()
		{
			var prop = BindableProperty.Create ("Foo", typeof(CastFromString), typeof(MockBindable), null);
			var bindable = new MockBindable ();

			Assert.Null (bindable.GetValue (prop));
			bindable.SetValue (prop, "foo");

			Assert.AreEqual ("foo", ((CastFromString)bindable.GetValue (prop)).Result);
		}

		class CastToString
		{
			string Result { get; set; }

			public CastToString (string result)
			{
				Result = result;
			}

			public static implicit operator string (CastToString source)
			{
				return source.Result;
			}

			public override string ToString ()
			{
				throw new InvalidOperationException ();
			}
		}

		[Test]
		public void SetValueCoreInvokesOpImplicitOnValue ()
		{
			var prop = BindableProperty.Create ("Foo", typeof(string), typeof(MockBindable), null);
			var bindable = new MockBindable ();

			Assert.Null (bindable.GetValue (prop));
			bindable.SetValue (prop, new CastToString ("foo"));

			Assert.AreEqual ("foo", bindable.GetValue (prop));
		}

		[Test]
		public void DefaultValueCreatorCalledForChangeDelegates ()
		{
			int changedOld = -1;
			int changedNew = -1;

			int changingOld = -1;
			int changingNew = -1;
			var prop = BindableProperty.Create ("Foo", typeof (int), typeof (MockBindable), 0, defaultValueCreator: b => 10,
			                                    propertyChanged: (b, value, newValue) => {
				                                    changedOld = (int) value;
				                                    changedNew = (int) newValue;
			                                    },
												propertyChanging: (b, value, newValue) => {
													changingOld = (int) value;
													changingNew = (int) newValue;
												});

			var bindable = new MockBindable ();


			var defaultValue = (int) bindable.GetValue (prop);

			Assert.AreEqual (10, defaultValue);

			bindable.SetValue (prop, 5);

			bindable.ClearValue (prop);

			Assert.AreEqual (5, changedOld);
			Assert.AreEqual (5, changingOld);
			Assert.AreEqual (10, changedNew);
			Assert.AreEqual (10, changingNew);
		}

		[Test]
		public void GetValuesDefaults()
		{
			var prop = BindableProperty.Create ("Foo", typeof(int), typeof(MockBindable), 0);
			var prop1 = BindableProperty.Create ("Foo1", typeof(int), typeof(MockBindable), 1);
			var prop2 = BindableProperty.Create ("Foo2", typeof(int), typeof(MockBindable), 2);
			var bindable = new MockBindable ();


			object[] values = bindable.GetValues (prop, prop1, prop2);
			Assert.That (values.Length == 3);
			Assert.That (values[0], Is.EqualTo (0));
			Assert.That (values[1], Is.EqualTo (1));
			Assert.That (values[2], Is.EqualTo (2));
		}

		[Test]
		public void GetValues()
		{
			var prop = BindableProperty.Create ("Foo", typeof(int), typeof(MockBindable), 0);
			var prop1 = BindableProperty.Create ("Foo1", typeof(int), typeof(MockBindable), 1);
			var prop2 = BindableProperty.Create ("Foo2", typeof(int), typeof(MockBindable), 2);
			var bindable = new MockBindable ();
			bindable.SetValue (prop, 3);
			bindable.SetValue (prop2, 5);


			object[] values = bindable.GetValues (prop, prop1, prop2);
			Assert.That (values.Length == 3);
			Assert.That (values[0], Is.EqualTo (3));
			Assert.That (values[1], Is.EqualTo (1));
			Assert.That (values[2], Is.EqualTo (5));
		}

		class BindingContextConverter
			: IValueConverter
		{
			public object Convert (object value, Type targetType, object parameter, CultureInfo culture)
			{
				return new MockViewModel { Text = value + "Converted" };
			}

			public object ConvertBack (object value, Type targetType, object parameter, CultureInfo culture)
			{
				throw new NotImplementedException();
			}
		}

		[Test]
		//https://bugzilla.xamarin.com/show_bug.cgi?id=24485
		public void BindingContextBoundThroughConverter()
		{
			var bindable = new MockBindable();
			bindable.BindingContext = "test";
			bindable.SetBinding (BindableObject.BindingContextProperty, new Binding (".", converter: new BindingContextConverter()));
			bindable.SetBinding (MockBindable.TextProperty, "Text");

			Assert.That (() => bindable.Text, Is.EqualTo ("testConverted"));
		}

		public class VMLocator
		{
			public event EventHandler Invoked;
			public int Count;
			public object VM {
				get {
					Count++;
					var eh = Invoked;
					if (eh != null)
						eh (this, EventArgs.Empty);
					return new object ();
				}
			}
		}

		[Test]
		//https://bugzilla.xamarin.com/show_bug.cgi?id=27299
		public void BindingOnBindingContextDoesntReapplyBindingContextBinding ()
		{
			var bindable = new MockBindable ();
			var locator = new VMLocator ();
			Assert.AreEqual (0, locator.Count);
			locator.Invoked += (sender, e) => Assert.IsTrue (locator.Count <= 1);
			bindable.SetBinding (BindableObject.BindingContextProperty, new Binding ("VM", source: locator));
			Assert.IsTrue (locator.Count == 1);
		}

		[Test]
		public void BindingsEditableAfterUnapplied()
		{
			var bindable = new MockBindable();

			var binding = new Binding (".");
			bindable.SetBinding (MockBindable.TextProperty, binding);
			bindable.BindingContext = "foo";

			Assume.That (bindable.Text, Is.EqualTo (bindable.BindingContext));

			bindable.RemoveBinding (MockBindable.TextProperty);

			Assert.That (() => binding.Path = "foo", Throws.Nothing);
		}

		[Test]
		// https://bugzilla.xamarin.com/show_bug.cgi?id=24054
		public void BindingsAppliedUnappliedWithNullContext()
		{
			var bindable = new MockBindable();

			var binding = new Binding (".");
			bindable.SetBinding (MockBindable.TextProperty, binding);
			bindable.BindingContext = "foo";

			Assume.That (bindable.Text, Is.EqualTo (bindable.BindingContext));

			bindable.BindingContext = null;

			Assume.That (bindable.Text, Is.EqualTo (bindable.BindingContext));

			bindable.BindingContext = "bar";

			Assume.That (bindable.Text, Is.EqualTo (bindable.BindingContext));

			bindable.RemoveBinding (MockBindable.TextProperty);

			Assert.That (() => binding.Path = "Foo", Throws.Nothing);
		}
	}
}