public void AddVertexFirstTest()
        {
            var poly = new Polygon2D(m_arrowVertices);
            var pos  = new Vector2(-5, 5);

            poly.AddVertexFirst(pos);
            Assert.AreEqual(5, poly.VertexCount);
            var vertices = (System.Collections.ICollection)poly.Vertices;

            Assert.Contains(pos, vertices);
        }