CellTests.cs

using NUnit.Framework;
using System;
using System.Threading.Tasks;

namespace Xamarin.Forms.Core.UnitTests
{
	[TestFixture]
	public class CellTests : BaseTestFixture
	{
		internal class TestCell : Cell
		{
			public bool OnAppearingSent { get; set; }
			public bool OnDisappearingSent { get; set; }

			protected override void OnAppearing ()
			{
				base.OnAppearing ();
				OnAppearingSent = true;
			}

			protected override void OnDisappearing ()
			{
				base.OnDisappearing ();
				OnDisappearingSent = true;
			}
		}

		[Test]
		public void Selected ()
		{
			var cell = new TestCell ();

			bool tapped = false;
			cell.Tapped += (sender, args) => tapped = true;

			cell.OnTapped();
			Assert.IsTrue (tapped);
		}

		[Test]
		public void AppearingEvent ()
		{
			var cell = new TestCell ();

			bool emitted = false;
			cell.Appearing += (sender, args) => emitted = true;

			cell.SendAppearing ();
			Assert.True (emitted);
			Assert.True (cell.OnAppearingSent);
			Assert.False (cell.OnDisappearingSent);
		}

		[Test]
		public void DisappearingEvent ()
		{
			var cell = new TestCell ();

			bool emitted = false;
			cell.Disappearing += (sender, args) => emitted = true;

			cell.SendDisappearing ();
			Assert.True (emitted);
			Assert.False (cell.OnAppearingSent);
			Assert.True (cell.OnDisappearingSent);
		}

		[Test]
		public void TestBindingContextPropagationOnImageCell ()
		{
			var context = new object ();
			var cell = new ImageCell ();
			cell.BindingContext = context;
			var source = new FileImageSource ();
			cell.ImageSource = source;
			Assert.AreSame (context, source.BindingContext);

			cell = new ImageCell ();
			source = new FileImageSource ();
			cell.ImageSource = source;
			cell.BindingContext = context;
			Assert.AreSame (context, source.BindingContext);
		}

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

			var cell = new TextCell();
			cell.PropertyChanged += (sender, args) => {
				if (args.PropertyName == "HasContextActions")
					changed = true;
			};

			Assert.That (cell.HasContextActions, Is.False);
			Assert.That (changed, Is.False);

			var collection = cell.ContextActions;

			Assert.That (cell.HasContextActions, Is.False);
			Assert.That (changed, Is.False);

			collection.Add (new MenuItem());

			Assert.That (cell.HasContextActions, Is.True);
			Assert.That (changed, Is.True);
		}

		[Test]
		public void MenuItemsGetBindingContext()
		{
			var cell = new TextCell {
				ContextActions = {
					new MenuItem ()
				}
			};

			object bc = new object ();

			cell.BindingContext = bc;
			Assert.That (cell.ContextActions [0].BindingContext, Is.SameAs (bc));

			cell = new TextCell { BindingContext = new object () };
			cell.ContextActions.Add (new MenuItem ());

			Assert.That (cell.ContextActions [0].BindingContext, Is.SameAs (cell.BindingContext));
		}

		[Test]
		public void RenderHeightINPCFromParent()
		{
			var lv = new ListView();
			var cell = new TextCell();
			cell.Parent = lv;

			int changing = 0, changed = 0;
			cell.PropertyChanging += (sender, args) => {
				if (args.PropertyName == "RenderHeight")
					changing++;
			};

			cell.PropertyChanged += (sender, args) => {
				if (args.PropertyName == "RenderHeight")
					changed++;
			};

			lv.RowHeight = 5;

			Assume.That (cell.RenderHeight, Is.EqualTo (5));

			Assert.That (changing, Is.EqualTo (1));
			Assert.That (changed, Is.EqualTo (1));
		}

		[Test]
		public async Task ForceUpdateSizeCallsAreRateLimited()
		{
			var lv = new ListView { HasUnevenRows = true };
			var cell = new ViewCell { Parent = lv };

			int numberOfCalls = 0;
			cell.ForceUpdateSizeRequested += (object sender, System.EventArgs e) => { numberOfCalls++; };

			cell.ForceUpdateSize ();
			cell.ForceUpdateSize ();
			cell.ForceUpdateSize ();
			cell.ForceUpdateSize ();

			await System.Threading.Tasks.Task.Delay (TimeSpan.FromMilliseconds (150));

			Assert.AreEqual (1, numberOfCalls);
		}

		[Test]
		public async Task ForceUpdateSizeWillNotBeCalledIfParentIsNotAListViewWithUnevenRows ()
		{
			var lv = new ListView { HasUnevenRows = false };
			var cell = new ViewCell { Parent = lv };

			int numberOfCalls = 0;
			cell.ForceUpdateSizeRequested += (object sender, System.EventArgs e) => { numberOfCalls++; };

			cell.ForceUpdateSize ();

			await System.Threading.Tasks.Task.Delay (TimeSpan.FromMilliseconds (16));

			Assert.AreEqual (0, numberOfCalls);
		}
	}
}