Added low-level Focus tests

UnitTests/Application/Application.NavigationTests.cs

@@ -83,4 +83,80 @@ public class ApplicationNavigationTests (ITestOutputHelper output)
         // Assert
         Assert.Equal (grandChildView, result);
     }
+
+    [Fact]
+    public void MoveNextView_ShouldMoveFocusToNextView ()
+    {
+        // Arrange
+        var top = new Toplevel ();
+        var view1 = new View () { Id = "view1", CanFocus = true };
+        var view2 = new View () { Id = "view2", CanFocus = true };
+        top.Add (view1, view2);
+        Application.Top = top;
+        Application.Current = top;
+        view1.SetFocus ();
+
+        // Act
+        ApplicationNavigation.MoveNextView ();
+
+        // Assert
+        Assert.True (view2.HasFocus);
+    }
+
+    [Fact]
+    public void MoveNextViewOrTop_ShouldMoveFocusToNextViewOrTop ()
+    {
+        // Arrange
+        var top = new Toplevel ();
+        var view1 = new View () { Id = "view1", CanFocus = true };
+        var view2 = new View () { Id = "view2", CanFocus = true };
+        top.Add (view1, view2);
+        Application.Top = top;
+        Application.Current = top;
+        view1.SetFocus ();
+
+        // Act
+        ApplicationNavigation.MoveNextViewOrTop ();
+
+        // Assert
+        Assert.True (view2.HasFocus);
+    }
+
+    [Fact]
+    public void MovePreviousView_ShouldMoveFocusToPreviousView ()
+    {
+        // Arrange
+        var top = new Toplevel ();
+        var view1 = new View () { Id = "view1", CanFocus = true };
+        var view2 = new View () { Id = "view2", CanFocus = true };
+        top.Add (view1, view2);
+        Application.Top = top;
+        Application.Current = top;
+        view2.SetFocus ();
+
+        // Act
+        ApplicationNavigation.MovePreviousView ();
+
+        // Assert
+        Assert.True (view1.HasFocus);
+    }
+
+    [Fact]
+    public void MovePreviousViewOrTop_ShouldMoveFocusToPreviousViewOrTop ()
+    {
+        // Arrange
+        var top = new Toplevel ();
+        var view1 = new View () { Id = "view1", CanFocus = true };
+        var view2 = new View () { Id = "view2", CanFocus = true };
+        top.Add (view1, view2);
+        Application.Top = top;
+        Application.Current = top;
+        view2.SetFocus ();
+
+        // Act
+        ApplicationNavigation.MovePreviousViewOrTop ();
+
+        // Assert
+        Assert.True (view1.HasFocus);
+    }
 }