@include test('valid(..)') {
  $tests: (
  '1.2.3': true,
  '1.2.3-alpha': true,
  '1.2.3-alpha.0': true,
  'a.b.c': false,
  '1.2.3.5': false,
  'NOT VALID': false,
  1.2: false,
  null: false,
 'Infinity.NaN.Infinity': false
  );

  @each $test, $expect in $tests {
    @include assert-equal(valid($test), $expect, 'Returns if version is valid.');
  }
}