public void Convert_XYZ_D65_to_sRGB(double x, double y, double z, double r, double g, double b)
        {
            // arange
            var input = new XYZColor(x, y, z);
            var converter = new ColourfulConverter { WhitePoint = Illuminants.D65, TargetRGBWorkingSpace = RGBWorkingSpaces.sRGB };

            // act
            RGBColor output = converter.ToRGB(input);

            // assert
            Assert.That(output.WorkingSpace, Is.EqualTo(RGBColor.DefaultWorkingSpace));
            Assert.That(output.R, Is.EqualTo(r).Using(DoubleComparer));
            Assert.That(output.G, Is.EqualTo(g).Using(DoubleComparer));
            Assert.That(output.B, Is.EqualTo(b).Using(DoubleComparer));
        }