All of the following are job duties of testing personnel EXCEPT:

The job duties of testing personnel typically revolve around the direct involvement in laboratory testing and processes related to specimen handling. Performing tests involves executing analytical processes to determine the presence or concentration of substances in various specimens. Handling specimens encompasses the receipt, processing, and storage of samples prior to testing, which is crucial for maintaining the integrity of the laboratory results.

While inventory control pertains to managing the supplies and reagents needed in the lab, it is generally a responsibility associated with laboratory management or support staff rather than testing personnel. Their roles focus more on conducting tests and handling specimens rather than administrative tasks like coding and billing, which are typically managed by a billing department or coding specialists. Therefore, coding and billing do not fall under the primary job duties of testing personnel, making it the correct option labeled as an exception.