public void CalculatePerlin_should_return_the_same_value_for_a_series_of_x_values()
        {
            var    perlin = new Perlin();
            double p1     = perlin.CalculatePerlin(0, 0, 0);
            double p2     = perlin.CalculatePerlin(1, 0, 0);
            double p3     = perlin.CalculatePerlin(2, 0, 0);
            double p4     = perlin.CalculatePerlin(3, 0, 0);

            p1.Should().Be(p2);
            p1.Should().Be(p3);
            p1.Should().Be(p4);
        }