public void DirToTest() { Point3D point = new Point3D() { X = 0, Y = 0, Z = 0 }; var result1 = point.DirTo(null); Assert.AreEqual(result1, 0); Point3D endPoint = new Point3D() { X = 1, Y = 1, Z = 1 }; var result2 = point.DirTo(endPoint); Assert.AreEqual(result2, 45 * Math.PI / 180); //包括Z轴 }