public function testCompareTo() { $dr1 = new DateRange(new DateTime('2006-07-08'), new DateTime('2006-09-05')); $dr2 = new DateRange(new DateTime('2006-09-06'), new DateTime('2006-09-15')); $this->assertEquals(-1, $dr1->compareTo($dr2)); $this->assertEquals(1, $dr2->compareTo($dr1)); $dr2 = clone $dr1; $this->assertEquals(0, $dr1->compareTo($dr2)); }