Tests, xmldoc and guards

UnitTests/Drawing/GradientFillTests.cs

@@ -1,6 +1,5 @@
-using Terminal.Gui.Drawing;
-
-namespace Terminal.Gui.TextEffects.Tests;
+
+namespace Terminal.Gui.DrawingTests;
 
 public class GradientFillTests
 {
@@ -29,9 +28,9 @@ public class GradientFillTests
 
         // Test the corners
         var topLeft = new Point (0, 0);
-        var topRight = new Point (area.Width, 0);
-        var bottomLeft = new Point (0, area.Height );
-        var bottomRight = new Point (area.Width, area.Height);
+        var topRight = new Point (area.Width - 1, 0);
+        var bottomLeft = new Point (0, area.Height - 1);
+        var bottomRight = new Point (area.Width - 1, area.Height - 1);
 
         var topLeftColor = gradientFill.GetColor (topLeft);
         var topRightColor = gradientFill.GetColor (topRight);

UnitTests/Drawing/GradientTests.cs

@@ -0,0 +1,53 @@
+
+namespace Terminal.Gui.DrawingTests;
+
+public class GradientTests
+{
+    // Static method to provide all enum values
+    public static IEnumerable<object []> GradientDirectionValues ()
+    {
+        return typeof (GradientDirection).GetEnumValues ()
+            .Cast<GradientDirection> ()
+            .Select (direction => new object [] { direction });
+    }
+
+    [Theory]
+    [MemberData (nameof (GradientDirectionValues))]
+    public void GradientIsInclusive_2_by_2 (GradientDirection direction)
+    {
+        // Define the colors of the gradient stops
+        var stops = new List<Color>
+            {
+                new Color(255, 0, 0),    // Red
+                new Color(0, 0, 255)     // Blue
+            };
+
+        // Define the number of steps between each color
+        var steps = new List<int> { 10 }; // 10 steps between Red -> Blue
+
+        var g = new Gradient (stops, steps, loop: false);
+        Assert.Equal (4, g.BuildCoordinateColorMapping (1, 1, direction).Count);
+    }
+
+    [Theory]
+    [MemberData (nameof (GradientDirectionValues))]
+    public void GradientIsInclusive_1_by_1 (GradientDirection direction)
+    {
+        // Define the colors of the gradient stops
+        var stops = new List<Color>
+            {
+                new Color(255, 0, 0),    // Red
+                new Color(0, 0, 255)     // Blue
+            };
+
+        // Define the number of steps between each color
+        var steps = new List<int> { 10 }; // 10 steps between Red -> Blue
+
+        var g = new Gradient (stops, steps, loop: false);
+
+        // Note that
+        var c = Assert.Single (g.BuildCoordinateColorMapping (0, 0, direction));
+        Assert.Equal (c.Key, new Point(0,0));
+        Assert.Equal (c.Value, new Color (0, 0, 255));
+    }
+}