None, that's not the point. Production control ensures that all the products are within a defined spec, and details the sampling and testing that will be performed during production and the actions that will be taken if any products are found to deviate. Lab tests are performed on a sample of products to prove the design.
I'm not aware of any LEGAL requirement to perform any specific tests during production for LVD products? I know of lots of options as most brands have their own set of QA procedures and product sampling tests (ISO or otherwise), some are great, others are, well, lets say designed to speed up production IME. Anyone that has had to deal with product recalls and performed root cause analysis will know how big batches can escape the "production controls" you mention! - All I'm saying is even "big brand" products could be "carp" and just because something has been made in China, doesn't automatically equal "unsafe" / "carp" products as they could well come out of the same factories with the same controls as the "big brand" products!