public function testSpanMath() { $s = new Horde_Date_Span(new Horde_Date(1), new Horde_Date(2)); $this->assertEquals(2, $s->add(1)->begin->timestamp()); $this->assertEquals(3, $s->add(1)->end->timestamp()); $this->assertEquals(0, $s->sub(1)->begin->timestamp()); $this->assertEquals(1, $s->sub(1)->end->timestamp()); }