public void AddVertexAfterTest()
        {
            var poly = new Polygon2D(m_arrowVertices);
            var pos  = new Vector2(0, 1);

            poly.AddVertexAfter(pos, m_arrowVertices[0]);
            Assert.AreEqual(5, poly.VertexCount);
            Assert.AreEqual(pos, poly.Vertices.ToList()[1]);

            Assert.Throws <ArgumentException>(() => poly.AddVertexAfter(pos, new Vector2(-99, 99)));
        }