In some cases, it may be necessary for you to have the product testing done at your facility. Other times, there may be a benefit to having testing done at your facility. In either case, there are pro's and con's for testing being performed at your facility vs. the certification lab.
Critical Questions for On-Site Testing: Do you have the specialized test equipment required by the standard? And, is the test equipment calibrated in accordance with the standard by an ISO17025 accredited calibration lab?
Reasons Why You May Be REQUIRED to Test at Your Facility:
On-Site Testing: Depending on the type of product, the benefits of onsite testing can be significant
Testing Large/Special Products at the Lab: Sometimes it still makes sense to test at the lab.