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

using System;
using NUnit.Framework;

namespace Xamarin.Forms.Core.UnitTests
{
	class MockBehavior<T> : Behavior<T> where T:BindableObject
	{
		public static int AttachCount { get; set; }
		public bool attached;
		public bool detached;

		protected override void OnAttachedTo (BindableObject bindable)
		{
			base.OnAttachedTo (bindable);
			attached = true;
			AttachCount++;
			AssociatedObject = bindable;
		}

		protected override void OnDetachingFrom (BindableObject bindable)
		{
			AttachCount--;
			detached = true;
			base.OnDetachingFrom (bindable);
			AssociatedObject = null;
		}

		public BindableObject AssociatedObject {get;set;}
	}

	[TestFixture]
	public class BehaviorTest : BaseTestFixture
	{
		[Test]
		public void AttachAndDetach ()
		{
			var behavior = new MockBehavior<MockBindable> ();
			var bindable = new MockBindable ();

			Assert.False (behavior.attached);
			Assert.False (behavior.detached);
			Assert.Null (behavior.AssociatedObject);

			((IAttachedObject)behavior).AttachTo (bindable);

			Assert.True (behavior.attached);
			Assert.False (behavior.detached);
			Assert.AreSame (bindable, behavior.AssociatedObject);

			((IAttachedObject)behavior).DetachFrom (bindable);

			Assert.True (behavior.attached);
			Assert.True (behavior.detached);
			Assert.Null (behavior.AssociatedObject);
		}

		[Test]
		public void AttachToTypeCompatibleWithTargetType ()
		{
			var behavior = new MockBehavior<MockBindable> ();
			var bindable = new View ();

			Assert.Throws<InvalidOperationException> (() => ((IAttachedObject)behavior).AttachTo (bindable));
		}
			
		[Test]
		public void BehaviorsInCollectionAreAttachedWhenCollectionIsAttached ()
		{
			var behavior = new MockBehavior<MockBindable> ();
			var collection = new AttachedCollection<Behavior> ();
			var bindable = new MockBindable ();
			collection.Add (behavior);
			Assert.Null (behavior.AssociatedObject);

			((IAttachedObject)collection).AttachTo (bindable);
			Assert.AreSame (bindable, behavior.AssociatedObject);

			((IAttachedObject)collection).DetachFrom (bindable);
			Assert.Null (behavior.AssociatedObject);
		}

		[Test]
		public void BehaviorsAddedToAttachedCollectionAreAttached ()
		{
			var behavior = new MockBehavior<MockBindable> ();
			var collection = new AttachedCollection<Behavior> ();
			var bindable = new MockBindable ();
			((IAttachedObject)collection).AttachTo (bindable);
			Assert.Null (behavior.AssociatedObject);

			collection.Add (behavior);
			Assert.AreSame (bindable, behavior.AssociatedObject);

			collection.Remove (behavior);
			Assert.Null (behavior.AssociatedObject);
		}

		[Test]
		public void TestBehaviorsAttachedDP ()
		{
			var behavior = new MockBehavior<MockBindable> ();
			var bindable = new MockBindable ();
			var collection = bindable.Behaviors;
			Assert.Null (behavior.AssociatedObject);

			collection.Add (behavior);
			Assert.AreSame (bindable, behavior.AssociatedObject);

			collection.Remove (behavior);
			Assert.Null (behavior.AssociatedObject);
		}
	}
}