Fix Table BoxStyle.Heavy body separation characters and add validator tests

Co-authored-by: tedd <493224+tedd@users.noreply.github.com>

Author: google-labs-jules[bot]

.jules/validator.md

@@ -1,3 +1,6 @@
 ## 2024-05-24 - Exhaustive Spatial and Hierarchical Validation of Table Component
 **Observation:** Auditing the `Table` component revealed requirements for robust testing against extreme constraints and explicit character verifications, especially when `BoxStyle.Heavy` is enabled. Traditional tests do not adequately cover the absolute positional accuracy of characters under dynamic grid-based hierarchical structures, nor do they isolate rendering behaviors when constrained to extremely tight boundaries (e.g., `Size(0,0)`). The control encapsulates complex subcomponents such as `ScrollViewer`, `TableRow`, and internal layout logic.
 **Strategic Action:** Developed an exhaustive validation suite (`ValidatorTableTests.cs`) under the xUnit framework. The matrix enforces: 1) Hierarchical Composition and Dynamic Mutation validation by embedding the `Table` alongside a `Border` within a proportionally-sized `Grid` and verifying structural integrity upon parent resize. 2) Coordinate-Precise Assertion evaluating the exact mapped placement of Unicode Box Drawing (`Heavy` style) symbols (e.g., `\u250F`, `\u2523`) against a `VirtualBuffer`. 3) Boundary verification enforcing correct behavior at `0x0` and `1x1` dimensions.
+## 2024-05-24 - Exhaustive Spatial and Hierarchical Validation of Table Component Body Separation
+**Observation:** Auditing the `Table` component revealed requirements for robust testing against extreme constraints and explicit character verifications, especially when `BoxStyle.Heavy` is enabled. Traditional tests do not adequately cover the absolute positional accuracy of characters under dynamic grid-based hierarchical structures. During this validation, an issue with `BoxStyle.Heavy` was identified: it was incorrectly utilizing mixed light/heavy characters for body separators (`\u2520` and `\u2542` instead of `\u2523` and `\u254B`).
+**Strategic Action:** Developed an exhaustive validation suite (`Table_CoordinatePreciseCharacterAssertion_HeavyBodySeparation`) under the xUnit framework inside `ValidatorTableTests.cs`. The matrix enforces: 1) Hierarchical Composition and Dynamic Mutation validation by embedding the `Table` alongside a `Border` within a `Grid` and verifying structural integrity upon parent resize. 2) Coordinate-Precise Assertion evaluating the exact mapped placement of Unicode Box Drawing (`Heavy` style) symbols (e.g., `\u2523`, `\u252B`, `\u254B`, `\u2501`) against a `VirtualBuffer`. Also updated the `Table.cs` struct values for Heavy table rendering.

src/Tedd.TUI.Tests/TableCoverageTests.cs

@@ -370,11 +370,11 @@ public void Table_Separator_Rendering()
         // X=8: Right Junction (u2528 ┨)
 
         // Verify Row 4
-        Assert.Equal('\u2520', buffer.GetPixel(0, 4).Character);
+        Assert.Equal('\u2523', buffer.GetPixel(0, 4).Character);
         Assert.Equal('\u2501', buffer.GetPixel(1, 4).Character);
         Assert.Equal('\u254B', buffer.GetPixel(4, 4).Character); // Cross
         Assert.Equal('\u2501', buffer.GetPixel(5, 4).Character);
-        Assert.Equal('\u2528', buffer.GetPixel(8, 4).Character);
+        Assert.Equal('\u252B', buffer.GetPixel(8, 4).Character);
     }
 
     [Fact]

src/Tedd.TUI.Tests/ValidatorTableTests.cs

@@ -373,6 +373,71 @@ public void Table_CoordinatePreciseCharacterAssertion_DoubleStyle()
         Assert.Equal('\u2562', buffer.GetPixel(11, 4).Character); // BodySepTRight
     }
 
+    [Fact]
+    public void Table_CoordinatePreciseCharacterAssertion_HeavyBodySeparation()
+    {
+        var table = new Table
+        {
+            ShowBorder = true,
+            ShowHeader = true,
+            ShowVerticalLines = true,
+            ShowHorizontalLines = true,
+            BorderStyle = BoxStyle.Heavy,
+            HorizontalAlignment = HorizontalAlignment.Left,
+            VerticalAlignment = VerticalAlignment.Top,
+            Width = 12,
+            Height = 10
+        };
+
+        var col1 = new TableColumn { Header = "ID", Width = new GridLength(3, GridUnitType.Pixel) };
+        var col2 = new TableColumn { Header = "Name", Width = new GridLength(4, GridUnitType.Pixel) };
+        table.Columns.Add(col1);
+        table.Columns.Add(col2);
+
+        // Add 2 rows to trigger row separators
+        table.AddRow("1", "Bob");
+        table.AddRow("2", "Alice");
+
+        // Use a grid to test hierarchical structure
+        var parentGrid = new Grid();
+        parentGrid.Children.Add(table);
+
+        var sv = table.GetVisualChild(0) as ScrollViewer;
+        if (sv != null)
+        {
+            sv.VerticalScrollBarVisibility = ScrollBarVisibility.Disabled;
+            sv.HorizontalScrollBarVisibility = ScrollBarVisibility.Disabled;
+        }
+
+        // Initial Layout
+        parentGrid.Measure(new Size(12, 10));
+        parentGrid.Arrange(new Rect(0, 0, 12, 10));
+
+        var buffer = new VirtualBuffer(12, 10);
+        parentGrid.Render(buffer, 0, 0);
+
+        // Header separator is at y=2
+        // Row 1 is at y=3
+        // Body separator is at y=4
+        Assert.Equal('\u2523', buffer.GetPixel(0, 4).Character); // BodySepTLeft (Heavy TLeft)
+        Assert.Equal('\u252B', buffer.GetPixel(11, 4).Character); // BodySepTRight (Heavy TRight)
+        Assert.Equal('\u254B', buffer.GetPixel(4, 4).Character); // BodySepCross (Heavy Cross)
+        Assert.Equal('\u2501', buffer.GetPixel(1, 4).Character); // BodySepH (Heavy Horizontal)
+
+        // Dynamic State Mutation
+        parentGrid.Measure(new Size(14, 12));
+        parentGrid.Arrange(new Rect(0, 0, 14, 12));
+
+        var newBuffer = new VirtualBuffer(14, 12);
+        parentGrid.Render(newBuffer, 0, 0);
+
+        // Verify again at the new resolution, since it is Top/Left aligned, positions remain the same
+        Assert.Equal('\u2523', newBuffer.GetPixel(0, 4).Character); // BodySepTLeft (Heavy TLeft)
+        Assert.Equal('\u252B', newBuffer.GetPixel(11, 4).Character); // BodySepTRight (Heavy TRight)
+        Assert.Equal('\u254B', newBuffer.GetPixel(4, 4).Character); // BodySepCross (Heavy Cross)
+        Assert.Equal('\u2501', newBuffer.GetPixel(1, 4).Character); // BodySepH (Heavy Horizontal)
+    }
+
     [Fact]
     public void Table_HierarchicalCompositionAndDynamicStateMutation_NestedGrids()
     {

src/Tedd.TUI/Table.cs

@@ -409,9 +409,10 @@ public static TableBoxChars Get(BoxStyle style)
                     c.TLeft = '\u2523';
                     c.TRight = '\u252B';
                     c.HeaderCross = '\u254B';
-                    c.BodySepTLeft = '\u2520';
-                    c.BodySepTRight = '\u2528';
-                    c.BodySepCross = '\u2542'; // ╂ (Heavy Vert, Light Horz)
+                    c.BodySepTLeft = '\u2523';
+                    c.BodySepTRight = '\u252B';
+                    c.BodySepCross = '\u254B'; // ╋ (Heavy Vert, Heavy Horz)
+                    c.BodySepH = '\u2501'; // ━ (Heavy Horz)
                     break;
                 case BoxStyle.Double:
                     c.TDown = '\u2566';