rple r calc(g * 2) 10)`, `rgb(102, 102, 10)`);
    test_valid_value(`color`, `rgb(from rebeccapurple b calc(r * .5) 10)`, `rgb(153, 51, 10)`);
    test_valid_value(`color`, `rgb(from rebeccapurple r calc(g * .5 + g * .5) 10)`, `rgb(102, 51, 10)`);
    test_valid_value(`color`, `rgb(from rebeccapurple r calc(b * .5 - g * .5) 10)`, `rgb(102, 51, 10)`);
    test_valid_value(`color`, `rgb(from rgb(20%, 40%, 60%, 80%) calc(r) calc(g) calc(b) / calc(alpha))`, `rgba(51, 102, 153, 0.8)`);

    // Testing with 'none