Fixed namespace, comments and added tests

Terminal.Gui/Views/TableView.cs

@@ -4,7 +4,7 @@ using System.Collections.Generic;
 using System.Data;
 using System.Linq;
 
-namespace Terminal.Gui.Views {
+namespace Terminal.Gui {
 
 	/// <summary>
 	/// Describes how to render a given column in  a <see cref="TableView"/> including <see cref="Alignment"/> and textual representation of cells (e.g. date formats)
@@ -148,23 +148,22 @@ namespace Terminal.Gui.Views {
 		public TableStyle Style { get => style; set {style = value; Update(); } }
 						
 		/// <summary>
-		/// Zero indexed offset for the upper left <see cref="DataColumn"/> to display in <see cref="Table"/>.
+		/// Horizontal scroll offset.  The index of the first column in <see cref="Table"/> to display when when rendering the view.
 		/// </summary>
 		/// <remarks>This property allows very wide tables to be rendered with horizontal scrolling</remarks>
 		public int ColumnOffset {
 			get => columnOffset;
 
 			//try to prevent this being set to an out of bounds column
-			set => columnOffset = Table == null ? 0 : Math.Min (Table.Columns.Count - 1, Math.Max (0, value));
+			set => columnOffset = Table == null ? 0 :Math.Max (0,Math.Min (Table.Columns.Count - 1,  value));
 		}
 
 		/// <summary>
-		/// Zero indexed offset for the <see cref="DataRow"/> to display in <see cref="Table"/> on line 2 of the control (first line being headers)
+		/// Vertical scroll offset.  The index of the first row in <see cref="Table"/> to display in the first non header line of the control when rendering the view.
 		/// </summary>
-		/// <remarks>This property allows very wide tables to be rendered with horizontal scrolling</remarks>
 		public int RowOffset {
 			get => rowOffset;
-			set => rowOffset = Table == null ? 0 : Math.Min (Table.Rows.Count - 1, Math.Max (0, value));
+			set => rowOffset = Table == null ? 0 : Math.Max (0,Math.Min (Table.Rows.Count - 1, value));
 		}
 
 		/// <summary>
@@ -666,7 +665,7 @@ namespace Terminal.Gui.Views {
 		/// <remarks>Changes will not be immediately visible in the display until you call <see cref="View.SetNeedsDisplay()"/></remarks>
 		public void EnsureSelectedCellIsVisible ()
 		{
-			if(Table == null){
+			if(Table == null || Table.Columns.Count <= 0){
 				return;
 			}
 

UICatalog/Scenarios/TableEditor.cs

@@ -2,7 +2,6 @@
 using System.Collections.Generic;
 using System.Data;
 using Terminal.Gui;
-using Terminal.Gui.Views;
 
 namespace UICatalog.Scenarios {
 

UnitTests/TableViewTests.cs

@@ -0,0 +1,98 @@
+using System;
+using System.Collections.Generic;
+using System.Data;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using Terminal.Gui;
+using Xunit;
+
+namespace UnitTests {
+	public class TableViewTests 
+	{
+
+        [Fact]
+        public void EnsureValidScrollOffsets_WithNoCells()
+        {
+            var tableView = new TableView();
+
+            Assert.Equal(0,tableView.RowOffset);
+            Assert.Equal(0,tableView.ColumnOffset);
+
+            // Set empty table
+            tableView.Table = new DataTable();
+
+            // Since table has no rows or columns scroll offset should default to 0
+            tableView.EnsureValidScrollOffsets();
+            Assert.Equal(0,tableView.RowOffset);
+            Assert.Equal(0,tableView.ColumnOffset);
+        }
+
+
+
+        [Fact]
+        public void EnsureValidScrollOffsets_LoadSmallerTable()
+        {
+            var tableView = new TableView();
+            tableView.Bounds = new Rect(0,0,25,10);
+
+            Assert.Equal(0,tableView.RowOffset);
+            Assert.Equal(0,tableView.ColumnOffset);
+
+            // Set big table
+            tableView.Table = BuildTable(25,50);
+
+            // Scroll down and along
+            tableView.RowOffset = 20;
+            tableView.ColumnOffset = 10;
+
+            tableView.EnsureValidScrollOffsets();
+
+            // The scroll should be valid at the moment
+            Assert.Equal(20,tableView.RowOffset);
+            Assert.Equal(10,tableView.ColumnOffset);
+
+            // Set small table
+            tableView.Table = BuildTable(2,2);
+
+            // Setting a small table should automatically trigger fixing the scroll offsets to ensure valid cells
+            Assert.Equal(0,tableView.RowOffset);
+            Assert.Equal(0,tableView.ColumnOffset);
+
+
+            // Trying to set invalid indexes should not be possible
+            tableView.RowOffset = 20;
+            tableView.ColumnOffset = 10;
+
+            Assert.Equal(1,tableView.RowOffset);
+            Assert.Equal(1,tableView.ColumnOffset);
+        }
+        
+        /// <summary>
+		/// Builds a simple table of string columns with the requested number of columns and rows
+		/// </summary>
+		/// <param name="cols"></param>
+		/// <param name="rows"></param>
+		/// <returns></returns>
+		public static DataTable BuildTable(int cols, int rows)
+		{
+			var dt = new DataTable();
+
+			for(int c = 0; c < cols; c++) {
+				dt.Columns.Add("Col"+c);
+			}
+				
+			for(int r = 0; r < rows; r++) {
+				var newRow = dt.NewRow();
+
+				for(int c = 0; c < cols; c++) {
+					newRow[c] = $"R{r}C{c}";
+				}
+
+				dt.Rows.Add(newRow);
+			}
+			
+			return dt;
+		}
+	}
+}