/**
* @covers ::add
*/
public function testAdd()
{
$span1 = new DaysSpan(new Days(5), new Days(7));
$span2 = new DaysSpan(new Days(5), new Days(13));
$expected = new DaysSpan(new Days(10), new Days(20));
$this->assertEquals($expected, $span1->add($span2));
}
