gui-cs.Terminal.Gui/UnitTests/View/Layout/DimTests.cs

using System;
using System.Collections.Generic;
using System.Globalization;
using System.Text;
using System.Threading;
using Xunit;
using Xunit.Abstractions;
// Alias Console to MockConsole so we don't accidentally use Console
using Console = Terminal.Gui.FakeConsole;

namespace Terminal.Gui.ViewTests;

public class DimTests {
	readonly ITestOutputHelper _output;

	public DimTests (ITestOutputHelper output)
	{
		_output = output;
		Console.OutputEncoding = Encoding.Default;
		// Change current culture
		var culture = CultureInfo.CreateSpecificCulture ("en-US");
		Thread.CurrentThread.CurrentCulture = culture;
		Thread.CurrentThread.CurrentUICulture = culture;
	}

	[Fact]
	public void New_Works ()
	{
		var dim = new Dim ();
		Assert.Equal ("Terminal.Gui.Dim", dim.ToString ());
	}

	[Fact]
	public void Sized_SetsValue ()
	{
		var dim = Dim.Sized (0);
		Assert.Equal ("Absolute(0)", dim.ToString ());

		var testVal = 5;
		dim = Dim.Sized (testVal);
		Assert.Equal ($"Absolute({testVal})", dim.ToString ());

		testVal = -1;
		dim = Dim.Sized (testVal);
		Assert.Equal ($"Absolute({testVal})", dim.ToString ());
	}

	[Fact]
	public void Sized_Equals ()
	{
		var n1 = 0;
		var n2 = 0;
		var dim1 = Dim.Sized (n1);
		var dim2 = Dim.Sized (n2);
		Assert.Equal (dim1, dim2);

		n1 = n2 = 1;
		dim1 = Dim.Sized (n1);
		dim2 = Dim.Sized (n2);
		Assert.Equal (dim1, dim2);

		n1 = n2 = -1;
		dim1 = Dim.Sized (n1);
		dim2 = Dim.Sized (n2);
		Assert.Equal (dim1, dim2);

		n1 = 0;
		n2 = 1;
		dim1 = Dim.Sized (n1);
		dim2 = Dim.Sized (n2);
		Assert.NotEqual (dim1, dim2);
	}

	[Fact]
	public void Width_Set_To_Null_Throws ()
	{
		var dim = Dim.Width (null);
		Assert.Throws<NullReferenceException> (() => dim.ToString ());
	}

	[Fact]
	[TestRespondersDisposed]
	public void SetsValue ()
	{
		var testVal = Rect.Empty;
		var testValView = new View (testVal);
		var dim = Dim.Width (testValView);
		Assert.Equal ($"View(Width,View(){testVal})", dim.ToString ());
		testValView.Dispose ();

		testVal = new Rect (1, 2, 3, 4);
		testValView = new View (testVal);
		dim = Dim.Width (testValView);
		Assert.Equal ($"View(Width,View(){testVal})", dim.ToString ());
		testValView.Dispose ();
	}

	[Fact]
	[TestRespondersDisposed]
	public void Width_Equals ()
	{
		var testRect1 = Rect.Empty;
		var view1 = new View (testRect1);
		var testRect2 = Rect.Empty;
		var view2 = new View (testRect2);

		var dim1 = Dim.Width (view1);
		var dim2 = Dim.Width (view1);
		// FIXED: Dim.Width should support Equals() and this should change to Equal.
		Assert.Equal (dim1, dim2);

		dim2 = Dim.Width (view2);
		Assert.NotEqual (dim1, dim2);

		testRect1 = new Rect (0, 1, 2, 3);
		view1 = new View (testRect1);
		testRect2 = new Rect (0, 1, 2, 3);
		dim1 = Dim.Width (view1);
		dim2 = Dim.Width (view1);
		// FIXED: Dim.Width should support Equals() and this should change to Equal.
		Assert.Equal (dim1, dim2);

		testRect1 = new Rect (0, -1, 2, 3);
		view1 = new View (testRect1);
		testRect2 = new Rect (0, -1, 2, 3);
		dim1 = Dim.Width (view1);
		dim2 = Dim.Width (view1);
		// FIXED: Dim.Width should support Equals() and this should change to Equal.
		Assert.Equal (dim1, dim2);

		testRect1 = new Rect (0, -1, 2, 3);
		view1 = new View (testRect1);
		testRect2 = Rect.Empty;
		view2 = new View (testRect2);
		dim1 = Dim.Width (view1);
		dim2 = Dim.Width (view2);
		Assert.NotEqual (dim1, dim2);
#if DEBUG_IDISPOSABLE
		// HACK: Force clean up of Responders to avoid having to Dispose all the Views created above.
		Responder.Instances.Clear ();
		Assert.Empty (Responder.Instances);
#endif
	}

	[Fact]
	public void Height_Set_To_Null_Throws ()
	{
		var dim = Dim.Height (null);
		Assert.Throws<NullReferenceException> (() => dim.ToString ());
	}

	[Fact]
	[TestRespondersDisposed]
	public void Height_SetsValue ()
	{
		var testVal = Rect.Empty;
		var testValview = new View (testVal);
		var dim = Dim.Height (testValview);
		Assert.Equal ($"View(Height,View(){testVal})", dim.ToString ());
		testValview.Dispose ();

		testVal = new Rect (1, 2, 3, 4);
		testValview = new View (testVal);
		dim = Dim.Height (testValview);
		Assert.Equal ($"View(Height,View(){testVal})", dim.ToString ());
		testValview.Dispose ();
	}

	// TODO: Other Dim.Height tests (e.g. Equal?)

	[Fact]
	public void Fill_SetsValue ()
	{
		var testMargin = 0;
		var dim = Dim.Fill ();
		Assert.Equal ($"Fill({testMargin})", dim.ToString ());

		testMargin = 0;
		dim = Dim.Fill (testMargin);
		Assert.Equal ($"Fill({testMargin})", dim.ToString ());

		testMargin = 5;
		dim = Dim.Fill (testMargin);
		Assert.Equal ($"Fill({testMargin})", dim.ToString ());
	}

	[Fact]
	public void Fill_Equal ()
	{
		var margin1 = 0;
		var margin2 = 0;
		var dim1 = Dim.Fill (margin1);
		var dim2 = Dim.Fill (margin2);
		Assert.Equal (dim1, dim2);
	}

	[Fact]
	public void Percent_SetsValue ()
	{
		float f = 0;
		var dim = Dim.Percent (f);
		Assert.Equal ($"Factor({f / 100:0.###},{false})", dim.ToString ());
		f = 0.5F;
		dim = Dim.Percent (f);
		Assert.Equal ($"Factor({f / 100:0.###},{false})", dim.ToString ());
		f = 100;
		dim = Dim.Percent (f);
		Assert.Equal ($"Factor({f / 100:0.###},{false})", dim.ToString ());
	}

	[Fact]
	public void Percent_Equals ()
	{
		float n1 = 0;
		float n2 = 0;
		var dim1 = Dim.Percent (n1);
		var dim2 = Dim.Percent (n2);
		Assert.Equal (dim1, dim2);

		n1 = n2 = 1;
		dim1 = Dim.Percent (n1);
		dim2 = Dim.Percent (n2);
		Assert.Equal (dim1, dim2);

		n1 = n2 = 0.5f;
		dim1 = Dim.Percent (n1);
		dim2 = Dim.Percent (n2);
		Assert.Equal (dim1, dim2);

		n1 = n2 = 100f;
		dim1 = Dim.Percent (n1);
		dim2 = Dim.Percent (n2);
		Assert.Equal (dim1, dim2);

		n1 = n2 = 0.3f;
		dim1 = Dim.Percent (n1, true);
		dim2 = Dim.Percent (n2, true);
		Assert.Equal (dim1, dim2);

		n1 = n2 = 0.3f;
		dim1 = Dim.Percent (n1);
		dim2 = Dim.Percent (n2, true);
		Assert.NotEqual (dim1, dim2);

		n1 = 0;
		n2 = 1;
		dim1 = Dim.Percent (n1);
		dim2 = Dim.Percent (n2);
		Assert.NotEqual (dim1, dim2);

		n1 = 0.5f;
		n2 = 1.5f;
		dim1 = Dim.Percent (n1);
		dim2 = Dim.Percent (n2);
		Assert.NotEqual (dim1, dim2);
	}

	[Fact]
	public void Percent_Invalid_Throws ()
	{
		var dim = Dim.Percent (0);
		Assert.Throws<ArgumentException> (() => dim = Dim.Percent (-1));
		Assert.Throws<ArgumentException> (() => dim = Dim.Percent (101));
		Assert.Throws<ArgumentException> (() => dim = Dim.Percent (100.0001F));
		Assert.Throws<ArgumentException> (() => dim = Dim.Percent (1000001));
	}

	// TODO: This actually a SetRelativeLayout/LayoutSubViews test and should be moved
	// TODO: A new test that calls SetRelativeLayout directly is needed.
	[Fact]
	[TestRespondersDisposed]
	public void Dim_Validation_Do_Not_Throws_If_NewValue_Is_DimAbsolute_And_OldValue_Is_Null ()
	{
		var t = new View ("top") { Width = 80, Height = 25 };

		var w = new Window (new Rect (1, 2, 4, 5)) { Title = "w" };
		t.Add (w);
		t.LayoutSubviews ();

		Assert.Equal (3, w.Width = 3);
		Assert.Equal (4, w.Height = 4);
		t.Dispose ();
	}

	// TODO: This actually a SetRelativeLayout/LayoutSubViews test and should be moved
	// TODO: A new test that calls SetRelativeLayout directly is needed.
	[Fact]
	[TestRespondersDisposed]
	public void Dim_Validation_Do_Not_Throws_If_NewValue_Is_DimAbsolute_And_OldValue_Is_Another_Type_After_Sets_To_LayoutStyle_Absolute ()
	{
		var t = new View ("top") { Width = 80, Height = 25 };

		var w = new Window {
			Width = Dim.Fill (),
			Height = Dim.Sized (10)
		};
		var v = new View ("v") {
			Width = Dim.Width (w) - 2,
			Height = Dim.Percent (10)
		};

		w.Add (v);
		t.Add (w);

		Assert.Equal (LayoutStyle.Absolute, t.LayoutStyle);
		Assert.Equal (LayoutStyle.Computed, w.LayoutStyle);
		Assert.Equal (LayoutStyle.Computed, v.LayoutStyle);

		t.LayoutSubviews ();
		Assert.Equal (2, v.Width = 2);
		Assert.Equal (2, v.Height = 2);

		// Force v to be LayoutStyle.Absolute;
		v.Frame = new Rect (0, 1, 3, 4);
		Assert.Equal (LayoutStyle.Absolute, v.LayoutStyle);
		t.LayoutSubviews ();

		Assert.Equal (2, v.Width = 2);
		Assert.Equal (2, v.Height = 2);
		t.Dispose ();
	}

	// TODO: This actually a SetRelativeLayout/LayoutSubViews test and should be moved
	// TODO: A new test that calls SetRelativeLayout directly is needed.
	[Fact]
	[AutoInitShutdown]
	public void Only_DimAbsolute_And_DimFactor_As_A_Different_Procedure_For_Assigning_Value_To_Width_Or_Height ()
	{
		// Testing with the Button because it properly handles the Dim class.
		var t = Application.Top;

		var w = new Window {
			Width = 100,
			Height = 100
		};

		var f1 = new FrameView ("f1") {
			X = 0,
			Y = 0,
			Width = Dim.Percent (50),
			Height = 5
		};

		var f2 = new FrameView ("f2") {
			X = Pos.Right (f1),
			Y = 0,
			Width = Dim.Fill (),
			Height = 5
		};

		var v1 = new Button ("v1") {
			AutoSize = false,
			X = Pos.X (f1) + 2,
			Y = Pos.Bottom (f1) + 2,
			Width = Dim.Width (f1) - 2,
			Height = Dim.Fill () - 2,
			ValidatePosDim = true
		};

		var v2 = new Button ("v2") {
			AutoSize = false,
			X = Pos.X (f2) + 2,
			Y = Pos.Bottom (f2) + 2,
			Width = Dim.Width (f2) - 2,
			Height = Dim.Fill () - 2,
			ValidatePosDim = true
		};

		var v3 = new Button ("v3") {
			AutoSize = false,
			Width = Dim.Percent (10),
			Height = Dim.Percent (10),
			ValidatePosDim = true
		};

		var v4 = new Button ("v4") {
			AutoSize = false,
			Width = Dim.Sized (50),
			Height = Dim.Sized (50),
			ValidatePosDim = true
		};

		var v5 = new Button ("v5") {
			AutoSize = false,
			Width = Dim.Width (v1) - Dim.Width (v3),
			Height = Dim.Height (v1) - Dim.Height (v3),
			ValidatePosDim = true
		};

		var v6 = new Button ("v6") {
			AutoSize = false,
			X = Pos.X (f2),
			Y = Pos.Bottom (f2) + 2,
			Width = Dim.Percent (20, true),
			Height = Dim.Percent (20, true),
			ValidatePosDim = true
		};

		w.Add (f1, f2, v1, v2, v3, v4, v5, v6);
		t.Add (w);

		t.Ready += (s, e) => {
			Assert.Equal ("Absolute(100)", w.Width.ToString ());
			Assert.Equal ("Absolute(100)", w.Height.ToString ());
			Assert.Equal (100, w.Frame.Width);
			Assert.Equal (100, w.Frame.Height);

			Assert.Equal ("Factor(0.5,False)", f1.Width.ToString ());
			Assert.Equal ("Absolute(5)", f1.Height.ToString ());
			Assert.Equal (49, f1.Frame.Width); // 50-1=49
			Assert.Equal (5, f1.Frame.Height);

			Assert.Equal ("Fill(0)", f2.Width.ToString ());
			Assert.Equal ("Absolute(5)", f2.Height.ToString ());
			Assert.Equal (49, f2.Frame.Width); // 50-1=49
			Assert.Equal (5, f2.Frame.Height);

			Assert.Equal ("Combine(View(Width,FrameView(f1)(0,0,49,5))-Absolute(2))", v1.Width.ToString ());
			Assert.Equal ("Combine(Fill(0)-Absolute(2))", v1.Height.ToString ());
			Assert.Equal (47, v1.Frame.Width);  // 49-2=47
			Assert.Equal (89, v1.Frame.Height); // 98-5-2-2=89

			Assert.Equal ("Combine(View(Width,FrameView(f2)(49,0,49,5))-Absolute(2))", v2.Width.ToString ());
			Assert.Equal ("Combine(Fill(0)-Absolute(2))", v2.Height.ToString ());
			Assert.Equal (47, v2.Frame.Width);  // 49-2=47
			Assert.Equal (89, v2.Frame.Height); // 98-5-2-2=89

			Assert.Equal ("Factor(0.1,False)", v3.Width.ToString ());
			Assert.Equal ("Factor(0.1,False)", v3.Height.ToString ());
			Assert.Equal (9, v3.Frame.Width);  // 98*10%=9
			Assert.Equal (9, v3.Frame.Height); // 98*10%=9

			Assert.Equal ("Absolute(50)", v4.Width.ToString ());
			Assert.Equal ("Absolute(50)", v4.Height.ToString ());
			Assert.Equal (50, v4.Frame.Width);
			Assert.Equal (50, v4.Frame.Height);

			Assert.Equal ("Combine(View(Width,Button(v1)(2,7,47,89))-View(Width,Button(v3)(0,0,9,9)))", v5.Width.ToString ());
			Assert.Equal ("Combine(View(Height,Button(v1)(2,7,47,89))-View(Height,Button(v3)(0,0,9,9)))", v5.Height.ToString ());
			Assert.Equal (38, v5.Frame.Width);  // 47-9=38
			Assert.Equal (80, v5.Frame.Height); // 89-9=80

			Assert.Equal ("Factor(0.2,True)", v6.Width.ToString ());
			Assert.Equal ("Factor(0.2,True)", v6.Height.ToString ());
			Assert.Equal (9, v6.Frame.Width);  // 47*20%=9
			Assert.Equal (18, v6.Frame.Height); // 89*20%=18

			w.Width = 200;
			Assert.True (t.LayoutNeeded);
			w.Height = 200;
			t.LayoutSubviews ();

			Assert.Equal ("Absolute(200)", w.Width.ToString ());
			Assert.Equal ("Absolute(200)", w.Height.ToString ());
			Assert.Equal (200, w.Frame.Width);
			Assert.Equal (200, w.Frame.Height);

			f1.Text = "Frame1";
			Assert.Equal ("Factor(0.5,False)", f1.Width.ToString ());
			Assert.Equal ("Absolute(5)", f1.Height.ToString ());
			Assert.Equal (99, f1.Frame.Width); // 100-1=99
			Assert.Equal (5, f1.Frame.Height);

			f2.Text = "Frame2";
			Assert.Equal ("Fill(0)", f2.Width.ToString ());
			Assert.Equal ("Absolute(5)", f2.Height.ToString ());
			Assert.Equal (99, f2.Frame.Width); // 100-1=99
			Assert.Equal (5, f2.Frame.Height);

			v1.Text = "Button1";
			Assert.Equal ("Combine(View(Width,FrameView(f1)(0,0,99,5))-Absolute(2))", v1.Width.ToString ());
			Assert.Equal ("Combine(Fill(0)-Absolute(2))", v1.Height.ToString ());
			Assert.Equal (97, v1.Frame.Width);  // 99-2=97
			Assert.Equal (189, v1.Frame.Height); // 198-2-7=189

			v2.Text = "Button2";
			Assert.Equal ("Combine(View(Width,FrameView(f2)(99,0,99,5))-Absolute(2))", v2.Width.ToString ());
			Assert.Equal ("Combine(Fill(0)-Absolute(2))", v2.Height.ToString ());
			Assert.Equal (97, v2.Frame.Width);  // 99-2=97
			Assert.Equal (189, v2.Frame.Height); // 198-2-7=189

			v3.Text = "Button3";
			Assert.Equal ("Factor(0.1,False)", v3.Width.ToString ());
			Assert.Equal ("Factor(0.1,False)", v3.Height.ToString ());
			Assert.Equal (19, v3.Frame.Width);  // 198*10%=19 * Percent is related to the super-view if it isn't null otherwise the view width
			Assert.Equal (19, v3.Frame.Height); // 199*10%=19

			v4.Text = "Button4";
			v4.AutoSize = false;
			Assert.Equal ("Absolute(50)", v4.Width.ToString ());
			Assert.Equal ("Absolute(50)", v4.Height.ToString ());
			Assert.Equal (50, v4.Frame.Width);
			Assert.Equal (50, v4.Frame.Height);
			v4.AutoSize = true;
			Assert.Equal ("Absolute(11)", v4.Width.ToString ());
			Assert.Equal ("Absolute(1)", v4.Height.ToString ());
			Assert.Equal (11, v4.Frame.Width);  // 11 is the text length and because is Dim.DimAbsolute
			Assert.Equal (1, v4.Frame.Height); // 1 because is Dim.DimAbsolute

			v5.Text = "Button5";
			Assert.Equal ("Combine(View(Width,Button(v1)(2,7,97,189))-View(Width,Button(v3)(0,0,19,19)))", v5.Width.ToString ());
			Assert.Equal ("Combine(View(Height,Button(v1)(2,7,97,189))-View(Height,Button(v3)(0,0,19,19)))", v5.Height.ToString ());
			Assert.Equal (78, v5.Frame.Width);  // 97-9=78
			Assert.Equal (170, v5.Frame.Height); // 189-19=170

			v6.Text = "Button6";
			Assert.Equal ("Factor(0.2,True)", v6.Width.ToString ());
			Assert.Equal ("Factor(0.2,True)", v6.Height.ToString ());
			Assert.Equal (19, v6.Frame.Width);  // 99*20%=19
			Assert.Equal (38, v6.Frame.Height); // 198-7*20=18
		};

		Application.Iteration += (s, a) => Application.RequestStop ();

		Application.Run ();
	}

	// See #2461
	//[Fact]
	//public void Dim_Referencing_SuperView_Throws ()
	//{
	//	var super = new View ("super") {
	//		Width = 10,
	//		Height = 10
	//	};
	//	var view = new View ("view") {
	//		Width = Dim.Width (super),	// this is not allowed
	//		Height = Dim.Height (super),    // this is not allowed
	//	};

	//	super.Add (view);
	//	super.BeginInit ();
	//	super.EndInit ();
	//	Assert.Throws<InvalidOperationException> (() => super.LayoutSubviews ());
	//}

	// TODO: This actually a SetRelativeLayout/LayoutSubViews test and should be moved
	// TODO: A new test that calls SetRelativeLayout directly is needed.

	/// <summary>
	/// This is an intentionally obtuse test. See https://github.com/gui-cs/Terminal.Gui/issues/2461
	/// </summary>
	[Fact]
	[TestRespondersDisposed]
	public void DimCombine_ObtuseScenario_Throw_If_SuperView_Refs_SubView ()
	{
		var t = new View { Width = 80, Height = 25 };

		var w = new Window {
			Width = Dim.Width (t) - 2,  // 78
			Height = Dim.Height (t) - 2 // 23
		};
		var f = new FrameView ();
		var v1 = new View {
			Width = Dim.Width (w) - 2,  // 76
			Height = Dim.Height (w) - 2 // 21
		};
		var v2 = new View {
			Width = Dim.Width (v1) - 2,  // 74
			Height = Dim.Height (v1) - 2 // 19
		};

		f.Add (v1, v2);
		w.Add (f);
		t.Add (w);
		t.BeginInit ();
		t.EndInit ();

		f.Width = Dim.Width (t) - Dim.Width (v2);    // 80 - 74 = 6
		f.Height = Dim.Height (t) - Dim.Height (v2); // 25 - 19 = 6

		Assert.Throws<InvalidOperationException> (t.LayoutSubviews);
		Assert.Equal (80, t.Frame.Width);
		Assert.Equal (25, t.Frame.Height);
		Assert.Equal (78, w.Frame.Width);
		Assert.Equal (23, w.Frame.Height);
		Assert.Equal (6, f.Frame.Width);
		Assert.Equal (6, f.Frame.Height);
		Assert.Equal (76, v1.Frame.Width);
		Assert.Equal (21, v1.Frame.Height);
		Assert.Equal (74, v2.Frame.Width);
		Assert.Equal (19, v2.Frame.Height);
		t.Dispose ();
	}

	// TODO: This actually a SetRelativeLayout/LayoutSubViews test and should be moved
	// TODO: A new test that calls SetRelativeLayout directly is needed.
	[Fact]
	[TestRespondersDisposed]
	public void DimCombine_ObtuseScenario_Does_Not_Throw_If_Two_SubViews_Refs_The_Same_SuperView ()
	{
		var t = new View ("top") { Width = 80, Height = 25 };

		var w = new Window {
			Width = Dim.Width (t) - 2,  // 78
			Height = Dim.Height (t) - 2 // 23
		};
		var f = new FrameView ();
		var v1 = new View {
			Width = Dim.Width (w) - 2,  // 76
			Height = Dim.Height (w) - 2 // 21
		};
		var v2 = new View {
			Width = Dim.Width (v1) - 2,  // 74
			Height = Dim.Height (v1) - 2 // 19
		};

		f.Add (v1, v2);
		w.Add (f);
		t.Add (w);
		t.BeginInit ();
		t.EndInit ();

		f.Width = Dim.Width (t) - Dim.Width (w) + 4;    // 80 - 74 = 6
		f.Height = Dim.Height (t) - Dim.Height (w) + 4; // 25 - 19 = 6

		// BUGBUG: v2 - f references t and w here; t is f's super-superview and w is f's superview. This is supported!
		var exception = Record.Exception (t.LayoutSubviews);
		Assert.Null (exception);
		Assert.Equal (80, t.Frame.Width);
		Assert.Equal (25, t.Frame.Height);
		Assert.Equal (78, w.Frame.Width);
		Assert.Equal (23, w.Frame.Height);
		Assert.Equal (6, f.Frame.Width);
		Assert.Equal (6, f.Frame.Height);
		Assert.Equal (76, v1.Frame.Width);
		Assert.Equal (21, v1.Frame.Height);
		Assert.Equal (74, v2.Frame.Width);
		Assert.Equal (19, v2.Frame.Height);
		t.Dispose ();
	}

	// TODO: This actually a SetRelativeLayout/LayoutSubViews test and should be moved
	// TODO: A new test that calls SetRelativeLayout directly is needed.
	[Fact]
	[TestRespondersDisposed]
	public void PosCombine_View_Not_Added_Throws ()
	{
		var t = new View { Width = 80, Height = 50 };

		var super = new View {
			Width = Dim.Width (t) - 2,
			Height = Dim.Height (t) - 2
		};
		t.Add (super);

		var sub = new View ();
		super.Add (sub);

		var v1 = new View {
			Width = Dim.Width (super) - 2,
			Height = Dim.Height (super) - 2
		};
		var v2 = new View {
			Width = Dim.Width (v1) - 2,
			Height = Dim.Height (v1) - 2
		};
		sub.Add (v1);
		// v2 not added to sub; should cause exception on Layout since it's referenced by sub.
		sub.Width = Dim.Fill () - Dim.Width (v2);
		sub.Height = Dim.Fill () - Dim.Height (v2);

		t.BeginInit ();
		t.EndInit ();

		Assert.Throws<InvalidOperationException> (() => t.LayoutSubviews ());
		t.Dispose ();
		v2.Dispose ();
	}

	// TODO: This actually a SetRelativeLayout/LayoutSubViews test and should be moved
	// A new test that does not depend on Application is needed.
	[Fact]
	[AutoInitShutdown]
	public void Dim_Add_Operator ()
	{
		var top = Application.Top;

		var view = new View { X = 0, Y = 0, Width = 20, Height = 0 };
		var field = new TextField { X = 0, Y = Pos.Bottom (view), Width = 20 };
		var count = 0;

		field.KeyDown += (s, k) => {
			if (k.KeyCode == KeyCode.Enter) {
				field.Text = $"Label {count}";
				var label = new Label (field.Text) { X = 0, Y = view.Bounds.Height, Width = 20 };
				view.Add (label);
				Assert.Equal ($"Label {count}", label.Text);
				Assert.Equal ($"Absolute({count})", label.Y.ToString ());

				Assert.Equal ($"Absolute({count})", view.Height.ToString ());
				view.Height += 1;
				count++;
				Assert.Equal ($"Absolute({count})", view.Height.ToString ());
			}
		};

		Application.Iteration += (s, a) => {
			while (count < 20) {
				field.NewKeyDownEvent (new Key (KeyCode.Enter));
			}

			Application.RequestStop ();
		};

		var win = new Window ();
		win.Add (view);
		win.Add (field);

		top.Add (win);

		Application.Run (top);

		Assert.Equal (20, count);
	}

	// TODO: This actually a SetRelativeLayout/LayoutSubViews test and should be moved
	// TODO: A new test that calls SetRelativeLayout directly is needed.
	[Fact]
	[AutoInitShutdown]
	public void Dim_Subtract_Operator ()
	{
		var top = Application.Top;

		var view = new View { X = 0, Y = 0, Width = 20, Height = 0 };
		var field = new TextField { X = 0, Y = Pos.Bottom (view), Width = 20 };
		var count = 20;
		var listLabels = new List<Label> ();

		for (int i = 0; i < count; i++) {
			field.Text = $"Label {i}";
			var label = new Label (field.Text) { X = 0, Y = view.Bounds.Height, Width = 20 };
			view.Add (label);
			Assert.Equal ($"Label {i}", label.Text);
			Assert.Equal ($"Absolute({i})", label.Y.ToString ());
			listLabels.Add (label);

			Assert.Equal ($"Absolute({i})", view.Height.ToString ());
			view.Height += 1;
			Assert.Equal ($"Absolute({i + 1})", view.Height.ToString ());
		}

		field.KeyDown += (s, k) => {
			if (k.KeyCode == KeyCode.Enter) {
				Assert.Equal ($"Label {count - 1}", listLabels [count - 1].Text);
				view.Remove (listLabels [count - 1]);
				listLabels [count - 1].Dispose ();

				Assert.Equal ($"Absolute({count})", view.Height.ToString ());
				view.Height -= 1;
				count--;
				Assert.Equal ($"Absolute({count})", view.Height.ToString ());
			}
		};

		Application.Iteration += (s, a) => {
			while (count > 0) {
				field.NewKeyDownEvent (new Key (KeyCode.Enter));
			}

			Application.RequestStop ();
		};

		var win = new Window ();
		win.Add (view);
		win.Add (field);

		top.Add (win);

		Application.Run (top);

		Assert.Equal (0, count);
	}

	[Fact]
	[TestRespondersDisposed]
	public void Internal_Tests ()
	{
		var dimFactor = new Dim.DimFactor (0.10F);
		Assert.Equal (10, dimFactor.Anchor (100));

		var dimAbsolute = new Dim.DimAbsolute (10);
		Assert.Equal (10, dimAbsolute.Anchor (0));

		var dimFill = new Dim.DimFill (1);
		Assert.Equal (99, dimFill.Anchor (100));

		var dimCombine = new Dim.DimCombine (true, dimFactor, dimAbsolute);
		Assert.Equal (dimCombine._left, dimFactor);
		Assert.Equal (dimCombine._right, dimAbsolute);
		Assert.Equal (20, dimCombine.Anchor (100));

		var view = new View (new Rect (20, 10, 20, 1));
		var dimViewHeight = new Dim.DimView (view, 0);
		Assert.Equal (1, dimViewHeight.Anchor (0));
		var dimViewWidth = new Dim.DimView (view, 1);
		Assert.Equal (20, dimViewWidth.Anchor (0));

		view.Dispose ();
	}

	[Fact]
	public void Function_SetsValue ()
	{
		var text = "Test";
		var dim = Dim.Function (() => text.Length);
		Assert.Equal ("DimFunc(4)", dim.ToString ());

		text = "New Test";
		Assert.Equal ("DimFunc(8)", dim.ToString ());

		text = "";
		Assert.Equal ("DimFunc(0)", dim.ToString ());
	}

	[Fact]
	public void Function_Equal ()
	{
		var f1 = () => 0;
		var f2 = () => 0;

		var dim1 = Dim.Function (f1);
		var dim2 = Dim.Function (f2);
		Assert.Equal (dim1, dim2);

		f2 = () => 1;
		dim2 = Dim.Function (f2);
		Assert.NotEqual (dim1, dim2);
	}

	// TODO: This actually a SetRelativeLayout/LayoutSubViews test and should be moved
	// TODO: A new test that calls SetRelativeLayout directly is needed.
	[Theory]
	[AutoInitShutdown]
	[InlineData (0, true)]
	[InlineData (0, false)]
	[InlineData (50, true)]
	[InlineData (50, false)]
	public void DimPercentPlusOne (int startingDistance, bool testHorizontal)
	{
		var container = new View {
			Width = 100,
			Height = 100
		};

		var label = new Label {
			X = testHorizontal ? startingDistance : 0,
			Y = testHorizontal ? 0 : startingDistance,
			Width = testHorizontal ? Dim.Percent (50) + 1 : 1,
			Height = testHorizontal ? 1 : Dim.Percent (50) + 1
		};

		container.Add (label);
		Application.Top.Add (container);
		Application.Top.BeginInit ();
		Application.Top.EndInit ();
		Application.Top.LayoutSubviews ();

		Assert.Equal (100, container.Frame.Width);
		Assert.Equal (100, container.Frame.Height);

		if (testHorizontal) {
			Assert.Equal (51, label.Frame.Width);
			Assert.Equal (1, label.Frame.Height);
		} else {
			Assert.Equal (1, label.Frame.Width);
			Assert.Equal (51, label.Frame.Height);
		}
	}

	// TODO: This actually a SetRelativeLayout/LayoutSubViews test and should be moved
	// TODO: A new test that calls SetRelativeLayout directly is needed.
	[Fact]
	[TestRespondersDisposed]
	public void Dim_Referencing_SuperView_Does_Not_Throw ()
	{
		var super = new View ("super") {
			Width = 10,
			Height = 10
		};
		var view = new View ("view") {
			Width = Dim.Width (super),  // this is allowed
			Height = Dim.Height (super) // this is allowed
		};

		super.Add (view);
		super.BeginInit ();
		super.EndInit ();

		var exception = Record.Exception (super.LayoutSubviews);
		Assert.Null (exception);
		super.Dispose ();
	}

	// TODO: This actually a SetRelativeLayout/LayoutSubViews test and should be moved
	// TODO: A new test that calls SetRelativeLayout directly is needed.
	[Fact]
	[TestRespondersDisposed]
	public void Dim_SyperView_Referencing_SubView_Throws ()
	{
		var super = new View ("super") {
			Width = 10,
			Height = 10
		};
		var view2 = new View ("view2") {
			Width = 10,
			Height = 10
		};
		var view = new View ("view") {
			Width = Dim.Width (view2),  // this is not allowed
			Height = Dim.Height (view2) // this is not allowed
		};

		view.Add (view2);
		super.Add (view);
		super.BeginInit ();
		super.EndInit ();

		Assert.Throws<InvalidOperationException> (super.LayoutSubviews);
		super.Dispose ();
	}
}