business\Holidays::addHoliday PHP Method

    public function addHoliday(\DateTime $holiday)
    {
        $this->holidays->attach($holiday);
    }

 public function testAddHoliday()
 {
     $holiday = new \DateTime('2015-05-11');
     $holidays = new Holidays();
     $holidays->addHoliday($holiday);
     $this->assertTrue($holidays->isHoliday($holiday));
 }