How do we QA the process of pixel tracking?

If a product is developed for the purpose of advertisers and there are advertisers who have their own data sets about which adverts are requested.

I do not have the access to advertisers data sets. Now there may be scenarios where an Advert is requested from Advertisers and the advert is not fully displayed. In that case, if advert is not fully displayed, it is not billable.

My developers have come up with the idea of Pixel Tracking where 1x1 pixel is requested for confirmation.

So How do I check this pixel Tracking? Any help will be greatly appreciated.