public function testMinus()
{
$point = new TimePoint(2012, 1, 1, 9, 30);
$this->assertEquals(new TimePoint(2009, 1, 1, 9, 30), $point->minus(new Duration(3, TimeUnit::year())));
$this->assertEquals(new TimePoint(2011, 9, 1, 9, 30), $point->minus(new Duration(4, TimeUnit::month())));
$this->assertEquals(new TimePoint(2011, 12, 30, 9, 30), $point->minus(new Duration(2, TimeUnit::day())));
$this->assertEquals(new TimePoint(2012, 1, 1, 6, 30), $point->minus(new Duration(3, TimeUnit::hour())));
$this->assertEquals(new TimePoint(2012, 1, 1, 9, 0), $point->minus(new Duration(30, TimeUnit::minute())));
}
public static function month($value)
{
return new Duration($value, TimeUnit::month());
}