1 files changed, 184 insertions, 0 deletions
diff --git a/Xamarin.Forms.Core.UnitTests/CommandSourceTests.cs b/Xamarin.Forms.Core.UnitTests/CommandSourceTests.cs
new file mode 100644
index 00000000..f544a297
--- /dev/null
+++ b/Xamarin.Forms.Core.UnitTests/CommandSourceTests.cs
@@ -0,0 +1,184 @@
+using System;
+using NUnit.Framework;
+
+namespace Xamarin.Forms.Core.UnitTests
+{
+	public abstract class CommandSourceTests<T> : BaseTestFixture
+		where T : BindableObject
+	{
+		[Test]
+		public void TestCommand ()
+		{
+			var source = CreateSource();
+
+			bool executed = false;
+			source.SetValue (CommandProperty, new Command (o => {
+				executed = true;
+				Assert.AreEqual (source, o);
+			}));
+
+			source.SetValue (CommandParameterProperty, source);
+
+			Activate (source);
+
+			Assert.True (executed);
+		}
+
+		[Test]
+		public void CommandCanExecuteModifiesEnabled ([Values(true, false)] bool initial)
+		{
+			bool canExecute = initial;
+			Command command;
+			var source = CreateSource();
+			source.SetValue (CommandProperty, command = new Command (() => { }, () => canExecute));
+
+			Assert.AreEqual (canExecute, source.GetValue (IsEnabledProperty));
+
+			canExecute = !initial;
+			command.ChangeCanExecute ();
+
+			Assert.AreEqual (canExecute, source.GetValue (IsEnabledProperty));
+		}
+
+		[Test]
+		public void ReenabledAfterCommandRemoved()
+		{
+			var source = CreateSource();
+			source.SetValue (CommandProperty, new Command (() => { }, () => false));
+
+			Assert.That (source.GetValue (IsEnabledProperty), Is.False);
+
+			source.SetValue (CommandProperty, null);
+
+			Assert.That (source.GetValue (IsEnabledProperty), Is.True);
+		}
+
+		[Test]
+		public void CommandUnhooksOnNull ()
+		{
+			bool canExecute = false;
+			Command command;
+			var source = CreateSource();
+
+			bool raised = false;
+			source.SetValue (CommandProperty, command = new Command (() => { }, () => {
+				raised = true;
+				return canExecute;
+			}));
+
+			raised = false;
+			source.SetValue (CommandProperty, null);
+
+			canExecute = true;
+			command.ChangeCanExecute ();
+
+			Assert.False (raised);
+		}
+
+		[Test]
+		public void CommandCanExecuteInvokedOnCommandSet ()
+		{
+			bool fired = false;
+			Func<bool> canExecute = () => {
+				fired = true;
+				return true;
+			};
+
+			Assert.IsFalse (fired);
+			var source = CreateSource();
+			source.SetValue (CommandProperty, new Command (() => { }, canExecute));
+
+			Assert.True (fired);
+		}
+
+		[Test]
+		public void CommandCanExecuteInvokedOnCommandParameterSet ()
+		{
+			bool fired;
+			Func<bool> canExecute = () => {
+				fired = true;
+				return true;
+			};
+
+			var source = CreateSource();
+			source.SetValue (CommandProperty, new Command (() => { }, canExecute));
+
+			fired = false;
+			Assert.IsFalse (fired);
+			source.SetValue (CommandParameterProperty, new object ());
+			Assert.True (fired);
+		}
+
+		[Test]
+		public void CommandCanExecuteInvokedOnChange()
+		{
+			bool fired;
+			Func<bool> canExecute = () => {
+				fired = true;
+				return true;
+			};
+
+			var cmd = new Command (() => { }, canExecute);
+			var source = CreateSource();
+			source.SetValue (CommandProperty, cmd);
+
+			fired = false;
+			
+			cmd.ChangeCanExecute();
+
+			Assert.That (fired, Is.True, "CanExecute was not called when the event was raised");
+		}
+
+		class BoolViewModel
+			: MockViewModel
+		{
+			bool toggle;
+
+			public bool Toggle
+			{
+				get { return toggle; }
+				set
+				{
+					if (toggle == value)
+						return;
+
+					toggle = value;
+					OnPropertyChanged();
+				}
+			}
+		}
+
+		[Test]
+		public void EnabledUpdatesDoNotRemoveBindings()
+		{
+			var vm = new BoolViewModel { Toggle = true };
+			var source = CreateSource();
+			source.BindingContext = vm;
+			source.SetBinding (IsEnabledProperty, "Toggle");
+
+			Assert.That (source.GetValue (IsEnabledProperty), Is.True);
+
+			source.SetValue (CommandProperty, new Command (() => { }));
+
+			Assert.That (source.GetIsBound (IsEnabledProperty), Is.True);
+		}
+
+		protected abstract T CreateSource();
+		protected abstract void Activate (T source);
+
+		protected abstract BindableProperty IsEnabledProperty
+		{
+			get;
+		}
+
+		protected abstract BindableProperty CommandProperty
+		{
+			get;
+		}
+
+		protected abstract BindableProperty CommandParameterProperty
+		{
+			get;
+		}
+	}
+}