public function testGetPercentageOfDropouts()
 {
     $total = 100;
     $num = (int) rand(1, 50);
     $expected = round(($total - $num) / $total * 100, AnalyticsExport::PERCENTAGE_PRECISION);
     $this->assertInstanceOf(AnalyticsExport::class, $this->instance->setStarts($total));
     $this->assertEquals($total, $this->instance->getStarts());
     $this->assertInstanceOf(AnalyticsExport::class, $this->instance->setCompletions($num));
     $this->assertEquals($num, $this->instance->getCompletions());
     $this->assertEquals($expected, $this->instance->getPercentageOfDropouts());
 }