The test looks for viable micro-organisms on consumables and medical devices presented as sterile: syringes, gauze, dressings, care sets.
It follows chapter 2.6.1 of the European Pharmacopoeia, by membrane filtration or direct inoculation depending on the article, with a fourteen-day incubation.
The sampling plan is defined with you, based on batch size and intended use. A sterility test covers a sample: it is not a guarantee that the whole batch is sterile, and that limit has to be understood before deciding what becomes of the batch.