- var_dump: documentation ( source)
<?php
var_dump(DateTime::createFromFormat(DateTime::RFC3339, '2012-06-30T23:59:59UTC'));
var_dump(DateTime::createFromFormat(DateTime::RFC3339, '2012-06-30T23:59:60UTC'));
var_dump(DateTime::createFromFormat(DateTime::RFC3339, '2012-07-01T00:00:00UTC'));