centage(input, result) {
  const number = input.to('percent').value / 100.;

  if (number < 0)
    assert_style_value_equals(result, new CSSUnitValue(0, 'number'));
  else if (number > 1)
    assert_style_value_equals(result, new CSSUnitValue(100, 'number'));
  else
    assert_style_value_equals(result, new CSSUnitValue(number, 'number'));
}

runPropertyTests('opacity', [
  {
    syntax: '<number>',
    computed: assert_is_equal_with_clamping_number
  },
  { syntax: '<percentage>',
    computed: assert_is_e