assertNull(ColorUtils.parseColourString("100,200,300")); // out of range
assertNull(ColorUtils.parseColourString("100,200")); // too few
assertNull(ColorUtils.parseColourString("100,200,100,200")); // too many
assertNull(ColorUtils.parseColourString("100,200,300")); // out of range
assertNull(ColorUtils.parseColourString("100,200")); // too few
assertNull(ColorUtils.parseColourString("100,200,100,200")); // too many