/**
  * test grabbing a Unit of Measure by an unitCode that does not exists
  **/
 public function testGetInvalidUnitOfMeasureByUnitCode()
 {
     // grab a unit code that does not exist
     $unitOfMeasure = UnitOfMeasure::getUnitOfMeasureByUnitCode($this->getPDO(), $this->INVALID_unitCode);
     $this->assertNull($unitOfMeasure);
 }