Fix Line2D.TryIntersect to pass nullable Point2D

src/Spatial.Tests/Euclidean/LineSegment2DTests.cs

@@ -139,14 +139,14 @@ public void IntersectWithTest(string s1, string e1, string s2, string e2, string
             Assert.AreEqual(e, result);
         }
 
-        [TestCase("0,0", "-2,-2", "1,0", "1,2", "1,1")]
-        [TestCase("0,0", "-2,-2", "0,1", "2,1", "1,1")]
-        [TestCase("0,0", "2,2", "-1,-5", "-1,0", "-1,-1")]
-        public void IntersectWithTest2(string s1, string e1, string s2, string e2, string expected)
+        [TestCase("0,0", "-2,-2", "1,0", "1,2")]
+        [TestCase("0,0", "-2,-2", "0,1", "2,1")]
+        [TestCase("0,0", "2,2", "-1,-5", "-1,0")]
+        public void IntersectWithTest2(string s1, string e1, string s2, string e2)
         {
             var line1 = LineSegment2D.Parse(s1, e1);
             var line2 = LineSegment2D.Parse(s2, e2);
-            var e = string.IsNullOrEmpty(expected) ? (Point2D?)null : Point2D.Parse(expected);
+            var e = (Point2D?)null;
             bool success = line1.TryIntersect(line2, out var result, Angle.FromRadians(0.001));
             Assert.IsFalse(success);
             Assert.AreEqual(e, result);

src/Spatial/Euclidean/LineSegment2D.cs

@@ -134,19 +134,19 @@ public Point2D ClosestPointTo(Point2D p)
         }
 
         /// <summary>
-        /// Compute the intersection between two lines if the angle between them is greater than a specified
+        /// Compute the intersection between two line segments if the angle between them is greater than a specified
         /// angle tolerance.
         /// </summary>
-        /// <param name="other">The other line to compute the intersection with</param>
-        /// <param name="intersection">When this method returns, contains the intersection point, if the conversion succeeded, or the default point if the conversion failed.</param>
-        /// <param name="tolerance">The tolerance used when checking if the lines are parallel</param>
+        /// <param name="other">The other line segment to compute the intersection with</param>
+        /// <param name="intersection">The intersection if it exists; otherwise null</param>
+        /// <param name="tolerance">The tolerance used when checking if the line segments are parallel</param>
         /// <returns>True if an intersection exists; otherwise false</returns>
         [Pure]
-        public bool TryIntersect(LineSegment2D other, out Point2D intersection, Angle tolerance)
+        public bool TryIntersect(LineSegment2D other, out Point2D? intersection, Angle tolerance)
         {
             if (this.IsParallelTo(other, tolerance))
             {
-                intersection = default(Point2D);
+                intersection = null;
                 return false;
             }
 
@@ -159,8 +159,17 @@ public bool TryIntersect(LineSegment2D other, out Point2D intersection, Angle to
             var t = (q - p).CrossProduct(s) / r.CrossProduct(s);
             var u = (p - q).CrossProduct(r) / s.CrossProduct(r);
 
-            intersection = p + (t * r);
-            return (0.0 <= t && t <= 1.0) && (0.0 <= u && u <= 1.0);
+            var isIntersected = (0.0 <= t && t <= 1.0) && (0.0 <= u && u <= 1.0);
+            if (isIntersected)
+            {
+                intersection = p + (t * r);
+                return true;
+            }
+            else
+            {
+                intersection = null;
+                return false;
+            }
         }
 
         /// <summary>