Piwik\Date::yesterday PHP Method

    public static function yesterday()
    {
        return new Date(strtotime("yesterday"));
    }

 /**
  * yesterday 23:59:59 is finished
  * @group Core
  */
 public function testDayIsFinishedYesterday()
 {
     $period = new Day(Date::yesterday());
     $this->assertEquals(date("Y-m-d", time() - 86400), $period->toString());
     $this->assertEquals(array(), $period->getSubperiods());
     $this->assertEquals(0, $period->getNumberOfSubperiods());
 }