/**
* Creates collection of comparable items
*
* If a type is not provided, the item type is dynamic.
*
* The item type must be a fully-qualified class name that implements:
* `Novuso\System\Type\Comparable`
*
* @param string|null $itemType The item type
*
* @return SortedSet
*/
public static function comparable(string $itemType = null) : SortedSet
{
assert(Validate::isNull($itemType) || Validate::implementsInterface($itemType, Comparable::class), sprintf('%s expects $itemType to implement %s', __METHOD__, Comparable::class));
return new static(new ComparableComparator(), $itemType);
}
/**
* @dataProvider invalidNullProvider
*/
public function test_that_is_null_returns_false_for_invalid_value($value)
{
$this->assertFalse(Validate::isNull($value));
}
