A cabling that provides the required performance is your first step to ensure robust data exchange. With cable testing of the relevant electrical parameters after installation, you avoid later troubles caused by, e.g. hidden mechanical damages, and improper connector attachments.
During network commissioning as the next step, the proper configuration and device parameterization shall be tested segment-wise.
With acceptance testing according to the predefined quality requirements you finally make sure that the individual segments of the network interact properly. A test report to prove the quality of your work is provided with the network handover to your customer.