public function testFilter()
{
$filter = new DateInterval();
$this->assertEquals(true, $filter->apply('P1M'));
$this->assertEquals(true, $filter->apply('P1Y4D'));
$this->assertEquals(true, $filter->apply('PT5M'));
$this->assertEquals(false, $filter->apply('P4D1Y'));
$this->assertEquals(false, $filter->apply('PM'));
$this->assertEquals(false, $filter->apply('foobar'));
// test error message
$this->assertErrorMessage($filter->getErrorMessage());
}
