e} calc(r) calc(g) calc(b) / calc(alpha))`,    `color(${colorSpace} 0.7 0.5 0.3 / 0.4)`);

        // Testing with 'none'.
        test_valid_value(`color`, `color(from color(${colorSpace} 0.7 0.5 0.3) ${colorSpace} none none none)`,                     `color(${colorSpace} none none none)`);
        test_valid_value(`color`, `color(from color(${colorSpace} 0.7 0.5 0.3) ${colorSpace} none none none / none)`,              `color(${colorSpace} none none none / none)`);
        test_valid_value(`color`, `color