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

using System;
using System.Collections.Generic;
using Xunit;
using Xunit.Abstractions;

// Alias Console to MockConsole so we don't accidentally use Console

namespace Terminal.Gui.ViewTests;

public class PosTests {
	readonly ITestOutputHelper _output;

	public PosTests (ITestOutputHelper output) => _output = output;

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

	[Fact]
	public void AnchorEnd_SetsValue ()
	{
		int n = 0;
		var pos = Pos.AnchorEnd ();
		Assert.Equal ($"AnchorEnd({n})", pos.ToString ());

		n = 5;
		pos = Pos.AnchorEnd (n);
		Assert.Equal ($"AnchorEnd({n})", pos.ToString ());
	}

	[Fact]
	public void AnchorEnd_Equal ()
	{
		int n1 = 0;
		int n2 = 0;

		var pos1 = Pos.AnchorEnd (n1);
		var pos2 = Pos.AnchorEnd (n2);
		Assert.Equal (pos1, pos2);

		// Test inequality
		n2 = 5;
		pos2 = Pos.AnchorEnd (n2);
		Assert.NotEqual (pos1, pos2);
	}

	[Fact]
	[AutoInitShutdown]
	public void AnchorEnd_Equal_Inside_Window ()
	{
		int viewWidth = 10;
		int viewHeight = 1;
		var tv = new TextView () {
			X = Pos.AnchorEnd (viewWidth),
			Y = Pos.AnchorEnd (viewHeight),
			Width = viewWidth,
			Height = viewHeight
		};

		var win = new Window ();

		win.Add (tv);

		var top = Application.Top;
		top.Add (win);
		var rs = Application.Begin (top);

		Assert.Equal (new Rect (0, 0, 80, 25), top.Frame);
		Assert.Equal (new Rect (0, 0, 80, 25), win.Frame);
		Assert.Equal (new Rect (68, 22, 10, 1), tv.Frame);
		Application.End (rs);
	}

	[Fact]
	[AutoInitShutdown]
	public void AnchorEnd_Equal_Inside_Window_With_MenuBar_And_StatusBar_On_Toplevel ()
	{
		int viewWidth = 10;
		int viewHeight = 1;
		var tv = new TextView () {
			X = Pos.AnchorEnd (viewWidth),
			Y = Pos.AnchorEnd (viewHeight),
			Width = viewWidth,
			Height = viewHeight
		};

		var win = new Window ();

		win.Add (tv);

		var menu = new MenuBar ();
		var status = new StatusBar ();
		var top = Application.Top;
		top.Add (win, menu, status);
		var rs = Application.Begin (top);

		Assert.Equal (new Rect (0, 0, 80, 25), top.Frame);
		Assert.Equal (new Rect (0, 0, 80, 1), menu.Frame);
		Assert.Equal (new Rect (0, 24, 80, 1), status.Frame);
		Assert.Equal (new Rect (0, 1, 80, 23), win.Frame);
		Assert.Equal (new Rect (68, 20, 10, 1), tv.Frame);

		Application.End (rs);
	}

	[Fact]
	[AutoInitShutdown]
	public void Bottom_Equal_Inside_Window ()
	{
		var win = new Window ();

		var label = new Label ("This should be the last line.") {
			TextAlignment = TextAlignment.Centered,
			ColorScheme = Colors.Menu,
			Width = Dim.Fill (),
			X = Pos.Center (),
			Y = Pos.Bottom (win) - 3 // two lines top and bottom borders more one line above the bottom border
		};

		win.Add (label);

		var top = Application.Top;
		top.Add (win);
		var rs = Application.Begin (top);
		((FakeDriver)Application.Driver).SetBufferSize (40, 10);

		Assert.True (label.AutoSize);
		Assert.Equal (new Rect (0, 0, 40, 10), top.Frame);
		Assert.Equal (new Rect (0, 0, 40, 10), win.Frame);
		Assert.Equal (new Rect (0, 7, 38, 1), label.Frame);
		string expected = @"
┌──────────────────────────────────────┐
│                                      │
│                                      │
│                                      │
│                                      │
│                                      │
│                                      │
│                                      │
│    This should be the last line.     │
└──────────────────────────────────────┘
";

		TestHelpers.AssertDriverContentsWithFrameAre (expected, _output);
		Application.End (rs);
	}

	[Fact]
	[AutoInitShutdown]
	public void AnchorEnd_Better_Than_Bottom_Equal_Inside_Window ()
	{
		var win = new Window ();

		var label = new Label ("This should be the last line.") {
			TextAlignment = TextAlignment.Centered,
			ColorScheme = Colors.Menu,
			Width = Dim.Fill (),
			X = Pos.Center (),
			Y = Pos.AnchorEnd (1)
		};

		win.Add (label);

		var top = Application.Top;
		top.Add (win);
		var rs = Application.Begin (top);
		((FakeDriver)Application.Driver).SetBufferSize (40, 10);

		Assert.True (label.AutoSize);
		Assert.Equal (29, label.Text.Length);
		Assert.Equal (new Rect (0, 0, 40, 10), top.Frame);
		Assert.Equal (new Rect (0, 0, 40, 10), win.Frame);
		Assert.Equal (new Rect (0, 7, 38, 1), label.Frame);
		string expected = @"
┌──────────────────────────────────────┐
│                                      │
│                                      │
│                                      │
│                                      │
│                                      │
│                                      │
│                                      │
│    This should be the last line.     │
└──────────────────────────────────────┘
";

		TestHelpers.AssertDriverContentsWithFrameAre (expected, _output);
		Application.End (rs);
	}

	[Fact]
	[AutoInitShutdown]
	public void Bottom_Equal_Inside_Window_With_MenuBar_And_StatusBar_On_Toplevel ()
	{
		var win = new Window ();

		var label = new Label ("This should be the last line.") {
			TextAlignment = TextAlignment.Centered,
			ColorScheme = Colors.Menu,
			Width = Dim.Fill (),
			X = Pos.Center (),
			Y = Pos.Bottom (win) - 4 // two lines top and bottom borders more two lines above border
		};

		win.Add (label);

		var menu = new MenuBar (new MenuBarItem [] { new ("Menu", "", null) });
		var status = new StatusBar (new StatusItem [] { new (KeyCode.F1, "~F1~ Help", null) });
		var top = Application.Top;
		top.Add (win, menu, status);
		var rs = Application.Begin (top);

		Assert.True (label.AutoSize);
		Assert.Equal (new Rect (0, 0, 80, 25), top.Frame);
		Assert.Equal (new Rect (0, 0, 80, 1), menu.Frame);
		Assert.Equal (new Rect (0, 24, 80, 1), status.Frame);
		Assert.Equal (new Rect (0, 1, 80, 23), win.Frame);
		Assert.Equal (new Rect (0, 20, 78, 1), label.Frame);
		string expected = @"
 Menu                                                                           
┌──────────────────────────────────────────────────────────────────────────────┐
│                                                                              │
│                                                                              │
│                                                                              │
│                                                                              │
│                                                                              │
│                                                                              │
│                                                                              │
│                                                                              │
│                                                                              │
│                                                                              │
│                                                                              │
│                                                                              │
│                                                                              │
│                                                                              │
│                                                                              │
│                                                                              │
│                                                                              │
│                                                                              │
│                                                                              │
│                                                                              │
│                        This should be the last line.                         │
└──────────────────────────────────────────────────────────────────────────────┘
 F1 Help                                                                        
";

		TestHelpers.AssertDriverContentsWithFrameAre (expected, _output);
		Application.End (rs);
	}

	[Fact]
	[AutoInitShutdown]
	public void AnchorEnd_Better_Than_Bottom_Equal_Inside_Window_With_MenuBar_And_StatusBar_On_Toplevel ()
	{
		var win = new Window ();

		var label = new Label ("This should be the last line.") {
			TextAlignment = TextAlignment.Centered,
			ColorScheme = Colors.Menu,
			Width = Dim.Fill (),
			X = Pos.Center (),
			Y = Pos.AnchorEnd (1)
		};

		win.Add (label);

		var menu = new MenuBar (new MenuBarItem [] { new ("Menu", "", null) });
		var status = new StatusBar (new StatusItem [] { new (KeyCode.F1, "~F1~ Help", null) });
		var top = Application.Top;
		top.Add (win, menu, status);
		var rs = Application.Begin (top);

		Assert.True (label.AutoSize);
		Assert.Equal (new Rect (0, 0, 80, 25), top.Frame);
		Assert.Equal (new Rect (0, 0, 80, 1), menu.Frame);
		Assert.Equal (new Rect (0, 24, 80, 1), status.Frame);
		Assert.Equal (new Rect (0, 1, 80, 23), win.Frame);
		Assert.Equal (new Rect (0, 20, 78, 1), label.Frame);
		string expected = @"
 Menu                                                                           
┌──────────────────────────────────────────────────────────────────────────────┐
│                                                                              │
│                                                                              │
│                                                                              │
│                                                                              │
│                                                                              │
│                                                                              │
│                                                                              │
│                                                                              │
│                                                                              │
│                                                                              │
│                                                                              │
│                                                                              │
│                                                                              │
│                                                                              │
│                                                                              │
│                                                                              │
│                                                                              │
│                                                                              │
│                                                                              │
│                                                                              │
│                        This should be the last line.                         │
└──────────────────────────────────────────────────────────────────────────────┘
 F1 Help                                                                        
";

		TestHelpers.AssertDriverContentsWithFrameAre (expected, _output);
		Application.End (rs);
	}

	[Fact]
	public void AnchorEnd_Negative_Throws ()
	{
		Pos pos;
		int n = -1;
		Assert.Throws<ArgumentException> (() => pos = Pos.AnchorEnd (n));
	}

	[Fact]
	public void At_SetsValue ()
	{
		var pos = Pos.At (0);
		Assert.Equal ("Absolute(0)", pos.ToString ());

		pos = Pos.At (5);
		Assert.Equal ("Absolute(5)", pos.ToString ());

		pos = Pos.At (-1);
		Assert.Equal ("Absolute(-1)", pos.ToString ());
	}

	[Fact]
	public void At_Equal ()
	{
		int n1 = 0;
		int n2 = 0;

		var pos1 = Pos.At (n1);
		var pos2 = Pos.At (n2);
		Assert.Equal (pos1, pos2);
	}

	[Fact]
	public void SetSide_Null_Throws ()
	{
		var pos = Pos.Left (null);
		Assert.Throws<NullReferenceException> (() => pos.ToString ());

		pos = Pos.X (null);
		Assert.Throws<NullReferenceException> (() => pos.ToString ());

		pos = Pos.Top (null);
		Assert.Throws<NullReferenceException> (() => pos.ToString ());

		pos = Pos.Y (null);
		Assert.Throws<NullReferenceException> (() => pos.ToString ());

		pos = Pos.Bottom (null);
		Assert.Throws<NullReferenceException> (() => pos.ToString ());

		pos = Pos.Right (null);
		Assert.Throws<NullReferenceException> (() => pos.ToString ());
	}

	// TODO: Test Left, Top, Right bottom Equal

	/// <summary>
	/// Tests Pos.Left, Pos.X, Pos.Top, Pos.Y, Pos.Right, and Pos.Bottom set operations
	/// </summary>
	[Fact]
	[TestRespondersDisposed]
	public void PosSide_SetsValue ()
	{
		string side; // used in format string
		var testRect = Rect.Empty;
		int testInt = 0;
		Pos pos;

		// Pos.Left
		side = "x";
		testInt = 0;
		testRect = Rect.Empty;
		pos = Pos.Left (new View ());
		Assert.Equal ($"View(side={side},target=View(){testRect})", pos.ToString ());

		pos = Pos.Left (new View (testRect));
		Assert.Equal ($"View(side={side},target=View(){testRect})", pos.ToString ());

		testRect = new Rect (1, 2, 3, 4);
		pos = Pos.Left (new View (testRect));
		Assert.Equal ($"View(side={side},target=View(){testRect})", pos.ToString ());

		// Pos.Left(win) + 0
		pos = Pos.Left (new View (testRect)) + testInt;
		Assert.Equal ($"Combine(View(side={side},target=View(){testRect}){(testInt < 0 ? '-' : '+')}Absolute({testInt}))", pos.ToString ());

		testInt = 1;
		// Pos.Left(win) +1
		pos = Pos.Left (new View (testRect)) + testInt;
		Assert.Equal ($"Combine(View(side={side},target=View(){testRect}){(testInt < 0 ? '-' : '+')}Absolute({testInt}))", pos.ToString ());

		testInt = -1;
		// Pos.Left(win) -1
		pos = Pos.Left (new View (testRect)) - testInt;
		Assert.Equal ($"Combine(View(side={side},target=View(){testRect}){(testInt < 0 ? '-' : '+')}Absolute({testInt}))", pos.ToString ());

		// Pos.X
		side = "x";
		testInt = 0;
		testRect = Rect.Empty;
		pos = Pos.X (new View ());
		Assert.Equal ($"View(side={side},target=View(){testRect})", pos.ToString ());

		pos = Pos.X (new View (testRect));
		Assert.Equal ($"View(side={side},target=View(){testRect})", pos.ToString ());

		testRect = new Rect (1, 2, 3, 4);
		pos = Pos.X (new View (testRect));
		Assert.Equal ($"View(side={side},target=View(){testRect})", pos.ToString ());

		// Pos.X(win) + 0
		pos = Pos.X (new View (testRect)) + testInt;
		Assert.Equal ($"Combine(View(side={side},target=View(){testRect}){(testInt < 0 ? '-' : '+')}Absolute({testInt}))", pos.ToString ());

		testInt = 1;
		// Pos.X(win) +1
		pos = Pos.X (new View (testRect)) + testInt;
		Assert.Equal ($"Combine(View(side={side},target=View(){testRect}){(testInt < 0 ? '-' : '+')}Absolute({testInt}))", pos.ToString ());

		testInt = -1;
		// Pos.X(win) -1
		pos = Pos.X (new View (testRect)) - testInt;
		Assert.Equal ($"Combine(View(side={side},target=View(){testRect}){(testInt < 0 ? '-' : '+')}Absolute({testInt}))", pos.ToString ());

		// Pos.Top
		side = "y";
		testInt = 0;
		testRect = Rect.Empty;
		pos = Pos.Top (new View ());
		Assert.Equal ($"View(side={side},target=View(){testRect})", pos.ToString ());

		pos = Pos.Top (new View (testRect));
		Assert.Equal ($"View(side={side},target=View(){testRect})", pos.ToString ());

		testRect = new Rect (1, 2, 3, 4);
		pos = Pos.Top (new View (testRect));
		Assert.Equal ($"View(side={side},target=View(){testRect})", pos.ToString ());

		// Pos.Top(win) + 0
		pos = Pos.Top (new View (testRect)) + testInt;
		Assert.Equal ($"Combine(View(side={side},target=View(){testRect}){(testInt < 0 ? '-' : '+')}Absolute({testInt}))", pos.ToString ());

		testInt = 1;
		// Pos.Top(win) +1
		pos = Pos.Top (new View (testRect)) + testInt;
		Assert.Equal ($"Combine(View(side={side},target=View(){testRect}){(testInt < 0 ? '-' : '+')}Absolute({testInt}))", pos.ToString ());

		testInt = -1;
		// Pos.Top(win) -1
		pos = Pos.Top (new View (testRect)) - testInt;
		Assert.Equal ($"Combine(View(side={side},target=View(){testRect}){(testInt < 0 ? '-' : '+')}Absolute({testInt}))", pos.ToString ());

		// Pos.Y
		side = "y";
		testInt = 0;
		testRect = Rect.Empty;
		pos = Pos.Y (new View ());
		Assert.Equal ($"View(side={side},target=View(){testRect})", pos.ToString ());

		pos = Pos.Y (new View (testRect));
		Assert.Equal ($"View(side={side},target=View(){testRect})", pos.ToString ());

		testRect = new Rect (1, 2, 3, 4);
		pos = Pos.Y (new View (testRect));
		Assert.Equal ($"View(side={side},target=View(){testRect})", pos.ToString ());

		// Pos.Y(win) + 0
		pos = Pos.Y (new View (testRect)) + testInt;
		Assert.Equal ($"Combine(View(side={side},target=View(){testRect}){(testInt < 0 ? '-' : '+')}Absolute({testInt}))", pos.ToString ());

		testInt = 1;
		// Pos.Y(win) +1
		pos = Pos.Y (new View (testRect)) + testInt;
		Assert.Equal ($"Combine(View(side={side},target=View(){testRect}){(testInt < 0 ? '-' : '+')}Absolute({testInt}))", pos.ToString ());

		testInt = -1;
		// Pos.Y(win) -1
		pos = Pos.Y (new View (testRect)) - testInt;
		Assert.Equal ($"Combine(View(side={side},target=View(){testRect}){(testInt < 0 ? '-' : '+')}Absolute({testInt}))", pos.ToString ());

		// Pos.Bottom
		side = "bottom";
		testRect = Rect.Empty;
		testInt = 0;
		pos = Pos.Bottom (new View ());
		Assert.Equal ($"View(side={side},target=View(){testRect})", pos.ToString ());

		pos = Pos.Bottom (new View (testRect));
		Assert.Equal ($"View(side={side},target=View(){testRect})", pos.ToString ());

		testRect = new Rect (1, 2, 3, 4);
		pos = Pos.Bottom (new View (testRect));
		Assert.Equal ($"View(side={side},target=View(){testRect})", pos.ToString ());

		// Pos.Bottom(win) + 0
		pos = Pos.Bottom (new View (testRect)) + testInt;
		Assert.Equal ($"Combine(View(side={side},target=View(){testRect}){(testInt < 0 ? '-' : '+')}Absolute({testInt}))", pos.ToString ());

		testInt = 1;
		// Pos.Bottom(win) +1
		pos = Pos.Bottom (new View (testRect)) + testInt;
		Assert.Equal ($"Combine(View(side={side},target=View(){testRect}){(testInt < 0 ? '-' : '+')}Absolute({testInt}))", pos.ToString ());

		testInt = -1;
		// Pos.Bottom(win) -1
		pos = Pos.Bottom (new View (testRect)) - testInt;
		Assert.Equal ($"Combine(View(side={side},target=View(){testRect}){(testInt < 0 ? '-' : '+')}Absolute({testInt}))", pos.ToString ());

#if DEBUG_IDISPOSABLE
		// HACK: Force clean up of Responders to avoid having to Dispose all the Views created above.
		Responder.Instances.Clear ();
#endif
	}

	// See: https://github.com/gui-cs/Terminal.Gui/issues/504
	[Fact]
	[TestRespondersDisposed]
	public void LeftTopBottomRight_Win_ShouldNotThrow ()
	{
		// Setup Fake driver
		(Window win, Button button) setup ()
		{
			Application.Init (new FakeDriver ());
			Application.Iteration += (s, a) => {
				Application.RequestStop ();
			};
			var win = new Window () {
				X = 0,
				Y = 0,
				Width = Dim.Fill (),
				Height = Dim.Fill ()
			};
			Application.Top.Add (win);

			var button = new Button ("button") {
				X = Pos.Center ()
			};
			win.Add (button);

			return (win, button);
		}

		RunState rs;

		void cleanup (RunState rs)
		{
			// Cleanup
			Application.End (rs);
			// Shutdown must be called to safely clean up Application if Init has been called
			Application.Shutdown ();
		}

		// Test cases:
		var app = setup ();
		app.button.Y = Pos.Left (app.win);
		rs = Application.Begin (Application.Top);
		// If Application.RunState is used then we must use Application.RunLoop with the rs parameter
		Application.RunLoop (rs);
		cleanup (rs);

		app = setup ();
		app.button.Y = Pos.X (app.win);
		rs = Application.Begin (Application.Top);
		// If Application.RunState is used then we must use Application.RunLoop with the rs parameter
		Application.RunLoop (rs);
		cleanup (rs);

		app = setup ();
		app.button.Y = Pos.Top (app.win);
		rs = Application.Begin (Application.Top);
		// If Application.RunState is used then we must use Application.RunLoop with the rs parameter
		Application.RunLoop (rs);
		cleanup (rs);

		app = setup ();
		app.button.Y = Pos.Y (app.win);
		rs = Application.Begin (Application.Top);
		// If Application.RunState is used then we must use Application.RunLoop with the rs parameter
		Application.RunLoop (rs);
		cleanup (rs);

		app = setup ();
		app.button.Y = Pos.Bottom (app.win);
		rs = Application.Begin (Application.Top);
		// If Application.RunState is used then we must use Application.RunLoop with the rs parameter
		Application.RunLoop (rs);
		cleanup (rs);

		app = setup ();
		app.button.Y = Pos.Right (app.win);
		rs = Application.Begin (Application.Top);
		// If Application.RunState is used then we must use Application.RunLoop with the rs parameter
		Application.RunLoop (rs);
		cleanup (rs);
	}

	[Fact]
	public void Center_SetsValue ()
	{
		var pos = Pos.Center ();
		Assert.Equal ("Center", pos.ToString ());
	}

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

	[Fact]
	public void Percent_Equal ()
	{
		float n1 = 0;
		float n2 = 0;
		var pos1 = Pos.Percent (n1);
		var pos2 = Pos.Percent (n2);
		Assert.Equal (pos1, pos2);

		n1 = n2 = 1;
		pos1 = Pos.Percent (n1);
		pos2 = Pos.Percent (n2);
		Assert.Equal (pos1, pos2);

		n1 = n2 = 0.5f;
		pos1 = Pos.Percent (n1);
		pos2 = Pos.Percent (n2);
		Assert.Equal (pos1, pos2);

		n1 = n2 = 100f;
		pos1 = Pos.Percent (n1);
		pos2 = Pos.Percent (n2);
		Assert.Equal (pos1, pos2);

		n1 = 0;
		n2 = 1;
		pos1 = Pos.Percent (n1);
		pos2 = Pos.Percent (n2);
		Assert.NotEqual (pos1, pos2);

		n1 = 0.5f;
		n2 = 1.5f;
		pos1 = Pos.Percent (n1);
		pos2 = Pos.Percent (n2);
		Assert.NotEqual (pos1, pos2);
	}

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

	[Fact]
	public void ForceValidatePosDim_True_Pos_Validation_Throws_If_NewValue_Is_PosAbsolute_And_OldValue_Is_Another_Type ()
	{
		Application.Init (new FakeDriver ());

		var t = Application.Top;

		var w = new Window () {
			X = Pos.Left (t) + 2,
			Y = Pos.At (2)
		};
		var v = new View () {
			X = Pos.Center (),
			Y = Pos.Percent (10),
			ValidatePosDim = true
		};

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

		t.Ready += (s, e) => {
			Assert.Equal (2, w.X = 2);
			Assert.Equal (2, w.Y = 2);
			Assert.Throws<ArgumentException> (() => v.X = 2);
			Assert.Throws<ArgumentException> (() => v.Y = 2);
		};

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

		Application.Run ();
		Application.Shutdown ();
	}

	[Fact]
	public void Pos_Validation_Do_Not_Throws_If_NewValue_Is_PosAbsolute_And_OldValue_Is_Null ()
	{
		Application.Init (new FakeDriver ());

		var t = Application.Top;

		var w = new Window (new Rect (1, 2, 4, 5));
		t.Add (w);

		t.Ready += (s, e) => {
			Assert.Equal (2, w.X = 2);
			Assert.Equal (2, w.Y = 2);
		};

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

		Application.Run ();
		Application.Shutdown ();

	}

	[Fact]
	public void Pos_Validation_Do_Not_Throws_If_NewValue_Is_PosAbsolute_And_OldValue_Is_Another_Type_After_Sets_To_LayoutStyle_Absolute ()
	{
		Application.Init (new FakeDriver ());

		var t = Application.Top;

		var w = new Window () {
			X = Pos.Left (t) + 2,
			Y = Pos.At (2)
		};
		var v = new View () {
			X = Pos.Center (),
			Y = Pos.Percent (10)
		};

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

		t.Ready += (s, e) => {
			v.LayoutStyle = LayoutStyle.Absolute;
			Assert.Equal (2, v.X = 2);
			Assert.Equal (2, v.Y = 2);
		};

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

		Application.Run ();
		Application.Shutdown ();
	}

	// DONE: Test PosCombine
	// DONE: Test operators
	// BUGBUG: v2 - This test is bogus. v1 and references it's superview's (f) superview (w). 
	//[Fact]
	//public void PosCombine_Do_Not_Throws ()
	//{
	//	Application.Init (new FakeDriver ());

	//	var w = new Window () {
	//		X = Pos.Left (Application.Top) + 2,
	//		Y = Pos.Top (Application.Top) + 2
	//	};
	//	var f = new FrameView ();
	//	var v1 = new View () {
	//		X = Pos.Left (w) + 2,
	//		Y = Pos.Top (w) + 2
	//	};
	//	var v2 = new View () {
	//		X = Pos.Left (v1) + 2,
	//		Y = Pos.Top (v1) + 2
	//	};

	//	f.Add (v1, v2);
	//	w.Add (f);
	//	Application.Top.Add (w);

	//	f.X = Pos.X (Application.Top) + Pos.X (v2) - Pos.X (v1);
	//	f.Y = Pos.Y (Application.Top) + Pos.Y (v2) - Pos.Y (v1);

	//	Application.Top.LayoutComplete += (s, e) => {
	//		Assert.Equal (0, Application.Top.Frame.X);
	//		Assert.Equal (0, Application.Top.Frame.Y);
	//		Assert.Equal (2, w.Frame.X);
	//		Assert.Equal (2, w.Frame.Y);
	//		Assert.Equal (2, f.Frame.X);
	//		Assert.Equal (2, f.Frame.Y);
	//		Assert.Equal (4, v1.Frame.X);
	//		Assert.Equal (4, v1.Frame.Y);
	//		Assert.Equal (6, v2.Frame.X);
	//		Assert.Equal (6, v2.Frame.Y);
	//	};

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

	//	Application.Run ();
	//	Application.Shutdown ();
	//}

	[Fact]
	[TestRespondersDisposed]
	public void PosCombine_Will_Throws ()
	{
		Application.Init (new FakeDriver ());

		var t = Application.Top;

		var w = new Window () {
			X = Pos.Left (t) + 2,
			Y = Pos.Top (t) + 2
		};
		var f = new FrameView ();
		var v1 = new View () {
			X = Pos.Left (w) + 2,
			Y = Pos.Top (w) + 2
		};
		var v2 = new View () {
			X = Pos.Left (v1) + 2,
			Y = Pos.Top (v1) + 2
		};

		f.Add (v1); // v2 not added
		w.Add (f);
		t.Add (w);

		f.X = Pos.X (v2) - Pos.X (v1);
		f.Y = Pos.Y (v2) - Pos.Y (v1);

		Assert.Throws<InvalidOperationException> (() => Application.Run ());
		Application.Shutdown ();

		v2.Dispose ();
	}

	[Fact]
	[TestRespondersDisposed]
	public void Pos_Add_Operator ()
	{
		Application.Init (new FakeDriver ());

		var top = Application.Top;

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

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

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

		// Shutdown must be called to safely clean up Application if Init has been called
		Application.Shutdown ();
	}

	[Fact]
	[TestRespondersDisposed]
	public void Pos_Subtract_Operator ()
	{
		Application.Init (new FakeDriver ());

		var top = Application.Top;

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

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

			Assert.Equal ($"Absolute({i})", field.Y.ToString ());
			field.Y += 1;
			Assert.Equal ($"Absolute({i + 1})", field.Y.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 ($"Absolute({count})", field.Y.ToString ());
				field.Y -= 1;
				count--;
				Assert.Equal ($"Absolute({count})", field.Y.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);

		// Shutdown must be called to safely clean up Application if Init has been called
		Application.Shutdown ();

	}

	[Fact]
	[TestRespondersDisposed]
	public void Internal_Tests ()
	{
		var posFactor = new Pos.PosFactor (0.10F);
		Assert.Equal (10, posFactor.Anchor (100));

		var posAnchorEnd = new Pos.PosAnchorEnd (1);
		Assert.Equal (99, posAnchorEnd.Anchor (100));

		var posCenter = new Pos.PosCenter ();
		Assert.Equal (50, posCenter.Anchor (100));

		var posAbsolute = new Pos.PosAbsolute (10);
		Assert.Equal (10, posAbsolute.Anchor (0));

		var posCombine = new Pos.PosCombine (true, posFactor, posAbsolute);
		Assert.Equal (posCombine._left, posFactor);
		Assert.Equal (posCombine._right, posAbsolute);
		Assert.Equal (20, posCombine.Anchor (100));

		posCombine = new Pos.PosCombine (true, posAbsolute, posFactor);
		Assert.Equal (posCombine._left, posAbsolute);
		Assert.Equal (posCombine._right, posFactor);
		Assert.Equal (20, posCombine.Anchor (100));

		var view = new View (new Rect (20, 10, 20, 1));
		var posViewX = new Pos.PosView (view, 0);
		Assert.Equal (20, posViewX.Anchor (0));
		var posViewY = new Pos.PosView (view, 1);
		Assert.Equal (10, posViewY.Anchor (0));
		var posRight = new Pos.PosView (view, 2);
		Assert.Equal (40, posRight.Anchor (0));
		var posViewBottom = new Pos.PosView (view, 3);
		Assert.Equal (11, posViewBottom.Anchor (0));

		view.Dispose ();
	}

	[Fact]
	public void Function_SetsValue ()
	{
		string text = "Test";
		var pos = Pos.Function (() => text.Length);
		Assert.Equal ("PosFunc(4)", pos.ToString ());

		text = "New Test";
		Assert.Equal ("PosFunc(8)", pos.ToString ());

		text = "";
		Assert.Equal ("PosFunc(0)", pos.ToString ());
	}

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

		var pos1 = Pos.Function (f1);
		var pos2 = Pos.Function (f2);
		Assert.Equal (pos1, pos2);

		f2 = () => 1;
		pos2 = Pos.Function (f2);
		Assert.NotEqual (pos1, pos2);
	}

	[Theory]
	[AutoInitShutdown]
	[InlineData (true)]
	[InlineData (false)]
	public void PosPercentPlusOne (bool testHorizontal)
	{
		var container = new View {
			Width = 100,
			Height = 100
		};

		var label = new Label {
			X = testHorizontal ? Pos.Percent (50) + Pos.Percent (10) + 1 : 1,
			Y = testHorizontal ? 1 : Pos.Percent (50) + Pos.Percent (10) + 1,
			Width = 10,
			Height = 10
		};

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

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

		if (testHorizontal) {
			Assert.Equal (61, label.Frame.X);
			Assert.Equal (1, label.Frame.Y);
		} else {
			Assert.Equal (1, label.Frame.X);
			Assert.Equal (61, label.Frame.Y);
		}
	}

	[Fact]
	public void PosCombine_Referencing_Same_View ()
	{
		var super = new View ("super") {
			Width = 10,
			Height = 10
		};
		var view1 = new View ("view1") {
			Width = 2,
			Height = 2
		};
		var view2 = new View ("view2") {
			Width = 2,
			Height = 2
		};
		view2.X = Pos.AnchorEnd () - (Pos.Right (view2) - Pos.Left (view2));

		super.Add (view1, view2);
		super.BeginInit ();
		super.EndInit ();

		var exception = Record.Exception (super.LayoutSubviews);
		Assert.Null (exception);
		Assert.Equal (new Rect (0, 0, 10, 10), super.Frame);
		Assert.Equal (new Rect (0, 0, 2, 2), view1.Frame);
		Assert.Equal (new Rect (8, 0, 2, 2), view2.Frame);

		super.Dispose ();
	}

	[Fact]
	public void DoNotReturnPosCombine ()
	{
		var v = new View () { Id = "V" };

		var pos = Pos.Left (v);
		Assert.Equal (
			"View(side=x,target=View(V)(0,0,0,0))",
			pos.ToString ());

		pos = Pos.X (v);
		Assert.Equal (
			"View(side=x,target=View(V)(0,0,0,0))",
			pos.ToString ());

		pos = Pos.Top (v);
		Assert.Equal (
			"View(side=y,target=View(V)(0,0,0,0))",
			pos.ToString ());

		pos = Pos.Y (v);
		Assert.Equal (
			"View(side=y,target=View(V)(0,0,0,0))",
			pos.ToString ());

		pos = Pos.Right (v);
		Assert.Equal (
			"View(side=right,target=View(V)(0,0,0,0))",
			pos.ToString ());

		pos = Pos.Bottom (v);
		Assert.Equal (
			"View(side=bottom,target=View(V)(0,0,0,0))",
			pos.ToString ());
	}
}