Add more tests.

src/Triangle.Tests/Helper.cs

@@ -0,0 +1,35 @@
+
+namespace TriangleNet.Tests
+{
+    using System.Collections.Generic;
+    using TriangleNet.Geometry;
+    using TriangleNet.Topology;
+
+    static class Helper
+    {
+        public static Contour Rectangle(double left, double top,
+            double right, double bottom, int mark = 0)
+        {
+            var points = new List<Vertex>(4);
+
+            points.Add(new Vertex(left, top, mark));
+            points.Add(new Vertex(right, top, mark));
+            points.Add(new Vertex(right, bottom, mark));
+            points.Add(new Vertex(left, bottom, mark));
+
+            return new Contour(points, mark, true);
+        }
+
+        public static Triangle CreateTriangle(int id, Vertex org, Vertex dest, Vertex apex)
+        {
+            var t = new Triangle() { id = id, hash = id };
+
+            // Node ordering 'plus 1 mod 3'.
+            t.vertices[0] = apex;
+            t.vertices[1] = org;
+            t.vertices[2] = dest;
+
+            return t;
+        }
+    }
+}