public void CanShiftPosition(float x1, float y1, float x2, float y2, float x3, float y3)
        {
            var pos = new Position2d(x1, y1);

            pos.Shift(x2, y2);

            DolphAssert.EqualF(x3, pos.X);
            DolphAssert.EqualF(y3, pos.Y);
        }
        public void TestHashCode()
        {
            var pos1 = new Position2d(1, 2);
            var pos2 = new Position2d(1, 2);

            Assert.Equal(pos1.GetHashCode(), pos2.GetHashCode());

            pos2.Shift(1, 1);

            Assert.NotEqual(pos1.GetHashCode(), pos2.GetHashCode());
        }