Scientist\Machine::execute PHP Method

    public function execute()
    {
        $this->setStartValues();
        $this->executeCallback();
        $this->setEndValues();
        return $this->result;
    }

 public function test_that_machine_can_determine_memory_usage_changes()
 {
     $m = new Machine(function () {
     });
     $r = $m->execute();
     $this->assertInternalType('integer', $r->getStartMemory());
     $this->assertInternalType('integer', $r->getEndMemory());
 }