public function testSetDate()
{
$time = '2000-01-02T03:14:25';
$immutable = new DateTimeImmutable($time);
$control = new DateTimeImmutable($time);
$mutable = new DateTime($time);
$new = $immutable->setDate(2005, 10, 20);
$mutable->setDate(2005, 10, 20);
$this->assertNotSame($immutable, $new);
$this->assertSame($control->format(DateTime::RFC3339), $immutable->format(DateTime::RFC3339));
$this->assertSame($mutable->format(DateTime::RFC3339), $new->format(DateTime::RFC3339));
}