 0.5 0.3 / 0.4)`);

        // Test nesting relative colors.
        test_valid_value(`color`, `color(from color(from color(${colorSpace} 0.7 0.5 0.3) ${colorSpace} r g b) ${colorSpace} r g b)`,   `color(${colorSpace} 0.7 0.5 0.3)`);

        // Testing replacement with 0.
        test_valid_value(`color`, `color(from color(${colorSpace} 0.7 0.5 0.3) ${colorSpace} 0 0 0)`,                              `color(${colorSpace} 0 0 0)`);
        test_valid_value(`color`, `color(from color(${colorSpace} 0.7 0.5 0.