Update PathTests.cs

Author: JimBobSquarePants

tests/ImageSharp.Drawing.Tests/Shapes/PathTests.cs

@@ -1,6 +1,8 @@
 // Copyright (c) Six Labors.
 // Licensed under the Six Labors Split License.
 
+using System.Numerics;
+
 namespace SixLabors.ImageSharp.Drawing.Tests.Shapes;
 
 /// <summary>
@@ -34,4 +36,53 @@ public void SimplePath()
         Assert.Equal(new PointF(10, 10), points[2]);
         Assert.Equal(new PointF(0, 10), points[3]);
     }
+
+    [Fact]
+    public void EmptyPath_SingletonsExposeExpectedPathTypes()
+    {
+        Assert.Same(EmptyPath.OpenPath, Path.Empty);
+        Assert.Equal(PathTypes.Open, EmptyPath.OpenPath.PathType);
+        Assert.Equal(PathTypes.Closed, EmptyPath.ClosedPath.PathType);
+    }
+
+    [Fact]
+    public void EmptyPath_OperationsPreserveSingletons()
+    {
+        Matrix4x4 transform = Matrix4x4.CreateTranslation(12, 34, 0);
+
+        Assert.Same(EmptyPath.ClosedPath, EmptyPath.OpenPath.AsClosedPath());
+        Assert.Same(EmptyPath.ClosedPath, EmptyPath.ClosedPath.AsClosedPath());
+        Assert.Same(EmptyPath.OpenPath, EmptyPath.OpenPath.Transform(transform));
+        Assert.Same(EmptyPath.ClosedPath, EmptyPath.ClosedPath.Transform(transform));
+    }
+
+    [Fact]
+    public void EmptyPath_ExposesNoPathData()
+    {
+        Assert.Equal(RectangleF.Empty, EmptyPath.OpenPath.Bounds);
+        Assert.Equal(RectangleF.Empty, EmptyPath.ClosedPath.Bounds);
+        Assert.Empty(EmptyPath.OpenPath.Flatten());
+        Assert.Empty(EmptyPath.ClosedPath.Flatten());
+    }
+
+    [Fact]
+    public void EmptyPath_ToLinearGeometry_ReturnsEmptyGeometry()
+    {
+        LinearGeometry identity = EmptyPath.OpenPath.ToLinearGeometry(Vector2.One);
+        LinearGeometry scaled = EmptyPath.ClosedPath.ToLinearGeometry(new Vector2(2F, 3F));
+
+        Assert.Same(identity, scaled);
+        Assert.Equal(RectangleF.Empty, identity.Info.Bounds);
+        Assert.Equal(0, identity.Info.ContourCount);
+        Assert.Equal(0, identity.Info.PointCount);
+        Assert.Equal(0, identity.Info.SegmentCount);
+        Assert.Equal(0, identity.Info.NonHorizontalSegmentCountPixelBoundary);
+        Assert.Equal(0, identity.Info.NonHorizontalSegmentCountPixelCenter);
+        Assert.Empty(identity.Contours);
+        Assert.Empty(identity.Points);
+
+        SegmentEnumerator segments = identity.GetSegments();
+
+        Assert.False(segments.MoveNext());
+    }
 }