Broke out PosView tests.

Added Equals test. Found bug. Fixed.

Terminal.Gui/View/Layout/Pos.cs

@@ -670,7 +670,7 @@ public class PosView (View view, Side side) : Pos
     public Side Side { get; } = side;
 
     /// <inheritdoc/>
-    public override bool Equals (object other) { return other is PosView abs && abs.Target == Target; }
+    public override bool Equals (object other) { return other is PosView abs && abs.Target == Target && abs.Side == Side; }
 
     /// <inheritdoc/>
     public override int GetHashCode () { return Target.GetHashCode (); }

UnitTests/View/Layout/Pos.CombineTests.cs

@@ -60,4 +60,82 @@ public class PosCombineTests (ITestOutputHelper output)
 
         v2.Dispose ();
     }
+
+
+    [Fact]
+    [SetupFakeDriver]
+    public void PosCombine_DimCombine_View_With_SubViews ()
+    {
+        var clicked = false;
+        Toplevel top = new Toplevel () { Width = 80, Height = 25 };
+        var win1 = new Window { Id = "win1", Width = 20, Height = 10 };
+        var view1 = new View
+        {
+            Text = "view1",
+            Width = Auto (DimAutoStyle.Text),
+            Height = Auto (DimAutoStyle.Text)
+
+        };
+        var win2 = new Window { Id = "win2", Y = Pos.Bottom (view1) + 1, Width = 10, Height = 3 };
+        var view2 = new View { Id = "view2", Width = Dim.Fill (), Height = 1, CanFocus = true };
+        view2.MouseClick += (sender, e) => clicked = true;
+        var view3 = new View { Id = "view3", Width = Dim.Fill (1), Height = 1, CanFocus = true };
+
+        view2.Add (view3);
+        win2.Add (view2);
+        win1.Add (view1, win2);
+        top.Add (win1);
+        top.BeginInit ();
+        top.EndInit ();
+
+        Assert.Equal (new Rectangle (0, 0, 80, 25), top.Frame);
+        Assert.Equal (new Rectangle (0, 0, 5, 1), view1.Frame);
+        Assert.Equal (new Rectangle (0, 0, 20, 10), win1.Frame);
+        Assert.Equal (new Rectangle (0, 2, 10, 3), win2.Frame);
+        Assert.Equal (new Rectangle (0, 0, 8, 1), view2.Frame);
+        Assert.Equal (new Rectangle (0, 0, 7, 1), view3.Frame);
+        var foundView = View.FindDeepestView (top, new (9, 4));
+        Assert.Equal (foundView, view2);
+    }
+
+    [Fact]
+    public void PosCombine_Refs_SuperView_Throws ()
+    {
+        Application.Init (new FakeDriver ());
+
+        var top = new Toplevel ();
+        var w = new Window { X = Pos.Left (top) + 2, Y = Pos.Top (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);
+        top.Add (w);
+        Application.Begin (top);
+
+        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 ();
+
+        Assert.Throws<InvalidOperationException> (() => Application.Run ());
+        top.Dispose ();
+        Application.Shutdown ();
+    }
+
 }

UnitTests/View/Layout/Pos.Tests.cs

@@ -497,325 +497,6 @@ public class PosTests (ITestOutputHelper output)
     }
 
 
-    // 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 PosView_Side_SetsValue ()
-    {
-        string side; // used in format string
-        var testRect = Rectangle.Empty;
-        var testInt = 0;
-        Pos pos;
-
-        // Pos.Left
-        side = "left";
-        testInt = 0;
-        testRect = Rectangle.Empty;
-        pos = Pos.Left (new ());
-        Assert.Equal ($"View(side={side},target=View(){testRect})", pos.ToString ());
-
-        pos = Pos.Left (new() { Frame = testRect });
-        Assert.Equal ($"View(side={side},target=View(){testRect})", pos.ToString ());
-
-        testRect = new (1, 2, 3, 4);
-        pos = Pos.Left (new() { Frame = testRect });
-        Assert.Equal ($"View(side={side},target=View(){testRect})", pos.ToString ());
-
-        // Pos.Left(win) + 0
-        pos = Pos.Left (new() { Frame = 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() { Frame = 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() { Frame = testRect }) - testInt;
-
-        Assert.Equal (
-                      $"Combine(View(side={side},target=View(){testRect}){(testInt < 0 ? '-' : '+')}Absolute({testInt}))",
-                      pos.ToString ()
-                     );
-
-        // Pos.X
-        side = "left";
-        testInt = 0;
-        testRect = Rectangle.Empty;
-        pos = Pos.X (new ());
-        Assert.Equal ($"View(side={side},target=View(){testRect})", pos.ToString ());
-
-        pos = Pos.X (new() { Frame = testRect });
-        Assert.Equal ($"View(side={side},target=View(){testRect})", pos.ToString ());
-
-        testRect = new (1, 2, 3, 4);
-        pos = Pos.X (new() { Frame = testRect });
-        Assert.Equal ($"View(side={side},target=View(){testRect})", pos.ToString ());
-
-        // Pos.X(win) + 0
-        pos = Pos.X (new() { Frame = 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() { Frame = 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() { Frame = testRect }) - testInt;
-
-        Assert.Equal (
-                      $"Combine(View(side={side},target=View(){testRect}){(testInt < 0 ? '-' : '+')}Absolute({testInt}))",
-                      pos.ToString ()
-                     );
-
-        // Pos.Top
-        side = "top";
-        testInt = 0;
-        testRect = Rectangle.Empty;
-        pos = Pos.Top (new ());
-        Assert.Equal ($"View(side={side},target=View(){testRect})", pos.ToString ());
-
-        pos = Pos.Top (new() { Frame = testRect });
-        Assert.Equal ($"View(side={side},target=View(){testRect})", pos.ToString ());
-
-        testRect = new (1, 2, 3, 4);
-        pos = Pos.Top (new() { Frame = testRect });
-        Assert.Equal ($"View(side={side},target=View(){testRect})", pos.ToString ());
-
-        // Pos.Top(win) + 0
-        pos = Pos.Top (new() { Frame = 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() { Frame = 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() { Frame = testRect }) - testInt;
-
-        Assert.Equal (
-                      $"Combine(View(side={side},target=View(){testRect}){(testInt < 0 ? '-' : '+')}Absolute({testInt}))",
-                      pos.ToString ()
-                     );
-
-        // Pos.Y
-        side = "top";
-        testInt = 0;
-        testRect = Rectangle.Empty;
-        pos = Pos.Y (new ());
-        Assert.Equal ($"View(side={side},target=View(){testRect})", pos.ToString ());
-
-        pos = Pos.Y (new() { Frame = testRect });
-        Assert.Equal ($"View(side={side},target=View(){testRect})", pos.ToString ());
-
-        testRect = new (1, 2, 3, 4);
-        pos = Pos.Y (new() { Frame = testRect });
-        Assert.Equal ($"View(side={side},target=View(){testRect})", pos.ToString ());
-
-        // Pos.Y(win) + 0
-        pos = Pos.Y (new() { Frame = 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() { Frame = 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() { Frame = testRect }) - testInt;
-
-        Assert.Equal (
-                      $"Combine(View(side={side},target=View(){testRect}){(testInt < 0 ? '-' : '+')}Absolute({testInt}))",
-                      pos.ToString ()
-                     );
-
-        // Pos.Bottom
-        side = "bottom";
-        testRect = Rectangle.Empty;
-        testInt = 0;
-        pos = Pos.Bottom (new ());
-        Assert.Equal ($"View(side={side},target=View(){testRect})", pos.ToString ());
-
-        pos = Pos.Bottom (new() { Frame = testRect });
-        Assert.Equal ($"View(side={side},target=View(){testRect})", pos.ToString ());
-
-        testRect = new (1, 2, 3, 4);
-        pos = Pos.Bottom (new() { Frame = testRect });
-        Assert.Equal ($"View(side={side},target=View(){testRect})", pos.ToString ());
-
-        // Pos.Bottom(win) + 0
-        pos = Pos.Bottom (new() { Frame = 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() { Frame = 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() { Frame = 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
-    }
-
-    [Fact]
-    public void PosView_Side_SetToNull_Throws ()
-    {
-        Pos 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: This actually a SetRelativeLayout/LayoutSubViews test and should be moved
-    // TODO: A new test that calls SetRelativeLayout directly is needed.
-    [Fact]
-    [TestRespondersDisposed]
-    public void Subtract_Operator ()
-    {
-        Application.Init (new FakeDriver ());
-
-        Toplevel top = new Toplevel ();
-
-        var view = new View { X = 0, Y = 0, Width = 20, Height = 20 };
-        var field = new TextField { X = 0, Y = 0, Width = 20 };
-        var count = 20;
-        List<View> listViews = new ();
-
-        for (var i = 0; i < count; i++)
-        {
-            field.Text = $"View {i}";
-            var view2 = new View { X = 0, Y = field.Y, Width = 20, Text = field.Text };
-            view.Add (view2);
-            Assert.Equal ($"View {i}", view2.Text);
-            Assert.Equal ($"Absolute({i})", field.Y.ToString ());
-            listViews.Add (view2);
-
-            Assert.Equal ($"Absolute({i})", field.Y.ToString ());
-            field.Y += 1;
-            Assert.Equal ($"Absolute({i + 1})", field.Y.ToString ());
-        }
-
-        field.KeyDown += (s, k) =>
-                         {
-                             if (k.KeyCode == KeyCode.Enter)
-                             {
-                                 Assert.Equal ($"View {count - 1}", listViews [count - 1].Text);
-                                 view.Remove (listViews [count - 1]);
-                                 listViews [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);
-        top.Dispose ();
-        Assert.Equal (0, count);
-
-        // Shutdown must be called to safely clean up Application if Init has been called
-        Application.Shutdown ();
-    }
-
     // TODO: This actually a SetRelativeLayout/LayoutSubViews test and should be moved
     // TODO: A new test that calls SetRelativeLayout directly is needed.
     [Fact]
@@ -840,82 +521,4 @@ public class PosTests (ITestOutputHelper output)
         t.Dispose ();
         Application.Shutdown ();
     }
-
-
-    [Fact]
-    [SetupFakeDriver]
-    public void PosCombine_DimCombine_View_With_SubViews ()
-    {
-        var clicked = false;
-        Toplevel top = new Toplevel () { Width = 80, Height = 25 };
-        var win1 = new Window { Id = "win1", Width = 20, Height = 10 };
-        var view1 = new View
-        {
-            Text = "view1",
-            Width = Auto (DimAutoStyle.Text),
-            Height = Auto (DimAutoStyle.Text)
-
-        }; 
-        var win2 = new Window { Id = "win2", Y = Pos.Bottom (view1) + 1, Width = 10, Height = 3 };
-        var view2 = new View { Id = "view2", Width = Dim.Fill (), Height = 1, CanFocus = true };
-        view2.MouseClick += (sender, e) => clicked = true;
-        var view3 = new View { Id = "view3", Width = Dim.Fill (1), Height = 1, CanFocus = true };
-
-        view2.Add (view3);
-        win2.Add (view2);
-        win1.Add (view1, win2);
-        top.Add (win1);
-        top.BeginInit ();
-        top.EndInit ();
-
-        Assert.Equal (new Rectangle (0, 0, 80, 25), top.Frame);
-        Assert.Equal (new Rectangle (0, 0, 5, 1), view1.Frame);
-        Assert.Equal (new Rectangle (0, 0, 20, 10), win1.Frame);
-        Assert.Equal (new Rectangle (0, 2, 10, 3), win2.Frame);
-        Assert.Equal (new Rectangle (0, 0, 8, 1), view2.Frame);
-        Assert.Equal (new Rectangle (0, 0, 7, 1), view3.Frame);
-        var foundView = View.FindDeepestView (top, new (9, 4));
-        Assert.Equal (foundView, view2);
-    }
-
-    [Fact]
-    public void PosCombine_Refs_SuperView_Throws ()
-    {
-        Application.Init (new FakeDriver ());
-
-        var top = new Toplevel ();
-        var w = new Window { X = Pos.Left (top) + 2, Y = Pos.Top (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);
-        top.Add (w);
-        Application.Begin (top);
-
-        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 ();
-
-        Assert.Throws<InvalidOperationException> (() => Application.Run ());
-        top.Dispose ();
-        Application.Shutdown ();
-    }
-
 }

UnitTests/View/Layout/Pos.ViewTests.cs

@@ -0,0 +1,345 @@
+using Xunit.Abstractions;
+using static Terminal.Gui.Pos;
+
+namespace Terminal.Gui.LayoutTests;
+
+public class PosViewTests (ITestOutputHelper output)
+{
+    private readonly ITestOutputHelper _output = output;
+
+    [Fact]
+    public void PosView_Equal ()
+    {
+        var view1 = new View ();
+        var view2 = new View ();
+
+        Pos pos1 = Left (view1);
+        Pos pos2 = Left (view1);
+        Assert.Equal (pos1, pos2);
+
+        pos2 = Left (view2);
+        Assert.NotEqual (pos1, pos2);
+
+        pos2 = Right (view1);
+        Assert.NotEqual (pos1, pos2);
+    }
+
+    // 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 PosView_Side_SetsValue ()
+    {
+        string side; // used in format string
+        var testRect = Rectangle.Empty;
+        var testInt = 0;
+        Pos pos;
+
+        // Pos.Left
+        side = "left";
+        testInt = 0;
+        testRect = Rectangle.Empty;
+        pos = Left (new ());
+        Assert.Equal ($"View(side={side},target=View(){testRect})", pos.ToString ());
+
+        pos = Left (new () { Frame = testRect });
+        Assert.Equal ($"View(side={side},target=View(){testRect})", pos.ToString ());
+
+        testRect = new (1, 2, 3, 4);
+        pos = Left (new () { Frame = testRect });
+        Assert.Equal ($"View(side={side},target=View(){testRect})", pos.ToString ());
+
+        // Pos.Left(win) + 0
+        pos = Left (new () { Frame = testRect }) + testInt;
+
+        Assert.Equal (
+                      $"Combine(View(side={side},target=View(){testRect}){(testInt < 0 ? '-' : '+')}Absolute({testInt}))",
+                      pos.ToString ()
+                     );
+
+        testInt = 1;
+
+        // Pos.Left(win) +1
+        pos = Left (new () { Frame = testRect }) + testInt;
+
+        Assert.Equal (
+                      $"Combine(View(side={side},target=View(){testRect}){(testInt < 0 ? '-' : '+')}Absolute({testInt}))",
+                      pos.ToString ()
+                     );
+
+        testInt = -1;
+
+        // Pos.Left(win) -1
+        pos = Left (new () { Frame = testRect }) - testInt;
+
+        Assert.Equal (
+                      $"Combine(View(side={side},target=View(){testRect}){(testInt < 0 ? '-' : '+')}Absolute({testInt}))",
+                      pos.ToString ()
+                     );
+
+        // Pos.X
+        side = "left";
+        testInt = 0;
+        testRect = Rectangle.Empty;
+        pos = X (new ());
+        Assert.Equal ($"View(side={side},target=View(){testRect})", pos.ToString ());
+
+        pos = X (new () { Frame = testRect });
+        Assert.Equal ($"View(side={side},target=View(){testRect})", pos.ToString ());
+
+        testRect = new (1, 2, 3, 4);
+        pos = X (new () { Frame = testRect });
+        Assert.Equal ($"View(side={side},target=View(){testRect})", pos.ToString ());
+
+        // Pos.X(win) + 0
+        pos = X (new () { Frame = testRect }) + testInt;
+
+        Assert.Equal (
+                      $"Combine(View(side={side},target=View(){testRect}){(testInt < 0 ? '-' : '+')}Absolute({testInt}))",
+                      pos.ToString ()
+                     );
+
+        testInt = 1;
+
+        // Pos.X(win) +1
+        pos = X (new () { Frame = testRect }) + testInt;
+
+        Assert.Equal (
+                      $"Combine(View(side={side},target=View(){testRect}){(testInt < 0 ? '-' : '+')}Absolute({testInt}))",
+                      pos.ToString ()
+                     );
+
+        testInt = -1;
+
+        // Pos.X(win) -1
+        pos = X (new () { Frame = testRect }) - testInt;
+
+        Assert.Equal (
+                      $"Combine(View(side={side},target=View(){testRect}){(testInt < 0 ? '-' : '+')}Absolute({testInt}))",
+                      pos.ToString ()
+                     );
+
+        // Pos.Top
+        side = "top";
+        testInt = 0;
+        testRect = Rectangle.Empty;
+        pos = Top (new ());
+        Assert.Equal ($"View(side={side},target=View(){testRect})", pos.ToString ());
+
+        pos = Top (new () { Frame = testRect });
+        Assert.Equal ($"View(side={side},target=View(){testRect})", pos.ToString ());
+
+        testRect = new (1, 2, 3, 4);
+        pos = Top (new () { Frame = testRect });
+        Assert.Equal ($"View(side={side},target=View(){testRect})", pos.ToString ());
+
+        // Pos.Top(win) + 0
+        pos = Top (new () { Frame = testRect }) + testInt;
+
+        Assert.Equal (
+                      $"Combine(View(side={side},target=View(){testRect}){(testInt < 0 ? '-' : '+')}Absolute({testInt}))",
+                      pos.ToString ()
+                     );
+
+        testInt = 1;
+
+        // Pos.Top(win) +1
+        pos = Top (new () { Frame = testRect }) + testInt;
+
+        Assert.Equal (
+                      $"Combine(View(side={side},target=View(){testRect}){(testInt < 0 ? '-' : '+')}Absolute({testInt}))",
+                      pos.ToString ()
+                     );
+
+        testInt = -1;
+
+        // Pos.Top(win) -1
+        pos = Top (new () { Frame = testRect }) - testInt;
+
+        Assert.Equal (
+                      $"Combine(View(side={side},target=View(){testRect}){(testInt < 0 ? '-' : '+')}Absolute({testInt}))",
+                      pos.ToString ()
+                     );
+
+        // Pos.Y
+        side = "top";
+        testInt = 0;
+        testRect = Rectangle.Empty;
+        pos = Y (new ());
+        Assert.Equal ($"View(side={side},target=View(){testRect})", pos.ToString ());
+
+        pos = Y (new () { Frame = testRect });
+        Assert.Equal ($"View(side={side},target=View(){testRect})", pos.ToString ());
+
+        testRect = new (1, 2, 3, 4);
+        pos = Y (new () { Frame = testRect });
+        Assert.Equal ($"View(side={side},target=View(){testRect})", pos.ToString ());
+
+        // Pos.Y(win) + 0
+        pos = Y (new () { Frame = testRect }) + testInt;
+
+        Assert.Equal (
+                      $"Combine(View(side={side},target=View(){testRect}){(testInt < 0 ? '-' : '+')}Absolute({testInt}))",
+                      pos.ToString ()
+                     );
+
+        testInt = 1;
+
+        // Pos.Y(win) +1
+        pos = Y (new () { Frame = testRect }) + testInt;
+
+        Assert.Equal (
+                      $"Combine(View(side={side},target=View(){testRect}){(testInt < 0 ? '-' : '+')}Absolute({testInt}))",
+                      pos.ToString ()
+                     );
+
+        testInt = -1;
+
+        // Pos.Y(win) -1
+        pos = Y (new () { Frame = testRect }) - testInt;
+
+        Assert.Equal (
+                      $"Combine(View(side={side},target=View(){testRect}){(testInt < 0 ? '-' : '+')}Absolute({testInt}))",
+                      pos.ToString ()
+                     );
+
+        // Pos.Bottom
+        side = "bottom";
+        testRect = Rectangle.Empty;
+        testInt = 0;
+        pos = Bottom (new ());
+        Assert.Equal ($"View(side={side},target=View(){testRect})", pos.ToString ());
+
+        pos = Bottom (new () { Frame = testRect });
+        Assert.Equal ($"View(side={side},target=View(){testRect})", pos.ToString ());
+
+        testRect = new (1, 2, 3, 4);
+        pos = Bottom (new () { Frame = testRect });
+        Assert.Equal ($"View(side={side},target=View(){testRect})", pos.ToString ());
+
+        // Pos.Bottom(win) + 0
+        pos = Bottom (new () { Frame = testRect }) + testInt;
+
+        Assert.Equal (
+                      $"Combine(View(side={side},target=View(){testRect}){(testInt < 0 ? '-' : '+')}Absolute({testInt}))",
+                      pos.ToString ()
+                     );
+
+        testInt = 1;
+
+        // Pos.Bottom(win) +1
+        pos = Bottom (new () { Frame = testRect }) + testInt;
+
+        Assert.Equal (
+                      $"Combine(View(side={side},target=View(){testRect}){(testInt < 0 ? '-' : '+')}Absolute({testInt}))",
+                      pos.ToString ()
+                     );
+
+        testInt = -1;
+
+        // Pos.Bottom(win) -1
+        pos = Bottom (new () { Frame = 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
+    }
+
+    [Fact]
+    public void PosView_Side_SetToNull_Throws ()
+    {
+        Pos pos = Left (null);
+        Assert.Throws<NullReferenceException> (() => pos.ToString ());
+
+        pos = X (null);
+        Assert.Throws<NullReferenceException> (() => pos.ToString ());
+
+        pos = Top (null);
+        Assert.Throws<NullReferenceException> (() => pos.ToString ());
+
+        pos = Y (null);
+        Assert.Throws<NullReferenceException> (() => pos.ToString ());
+
+        pos = Bottom (null);
+        Assert.Throws<NullReferenceException> (() => pos.ToString ());
+
+        pos = Right (null);
+        Assert.Throws<NullReferenceException> (() => pos.ToString ());
+    }
+
+    // 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 Subtract_Operator ()
+    {
+        Application.Init (new FakeDriver ());
+
+        var top = new Toplevel ();
+
+        var view = new View { X = 0, Y = 0, Width = 20, Height = 20 };
+        var field = new TextField { X = 0, Y = 0, Width = 20 };
+        var count = 20;
+        List<View> listViews = new ();
+
+        for (var i = 0; i < count; i++)
+        {
+            field.Text = $"View {i}";
+            var view2 = new View { X = 0, Y = field.Y, Width = 20, Text = field.Text };
+            view.Add (view2);
+            Assert.Equal ($"View {i}", view2.Text);
+            Assert.Equal ($"Absolute({i})", field.Y.ToString ());
+            listViews.Add (view2);
+
+            Assert.Equal ($"Absolute({i})", field.Y.ToString ());
+            field.Y += 1;
+            Assert.Equal ($"Absolute({i + 1})", field.Y.ToString ());
+        }
+
+        field.KeyDown += (s, k) =>
+                         {
+                             if (k.KeyCode == KeyCode.Enter)
+                             {
+                                 Assert.Equal ($"View {count - 1}", listViews [count - 1].Text);
+                                 view.Remove (listViews [count - 1]);
+                                 listViews [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 (KeyCode.Enter));
+                                     }
+
+                                     Application.RequestStop ();
+                                 };
+
+        var win = new Window ();
+        win.Add (view);
+        win.Add (field);
+
+        top.Add (win);
+
+        Application.Run (top);
+        top.Dispose ();
+        Assert.Equal (0, count);
+
+        // Shutdown must be called to safely clean up Application if Init has been called
+        Application.Shutdown ();
+    }
+}