A method is disclosed in which a vapor-deposited coating or layer is directly or indirectly applied to at least a portion of the internal wall of the barrel of a capped pre-assembly comprising a barrel, optionally a dispensing portion, and a cap. The cap is secured to the barrel and at least substantially isolates the distal opening of the dispensing portion from pressure conditions outside the cap. A vapor-deposited coating or layer is applied directly or indirectly to at least a portion of the internal wall of the barrel while the pre-assembly is capped. The coating or layer is applied under conditions effective to maintain communication from the barrel lumen to the exterior via the front opening, optionally further via the dispensing portion lumen if present, at the end of the applying step. The capped pre-assembly can be pressure tested easily and rapidly, for example with a test duration between 1 and 60 seconds, to determine whether it has container closure integrity.