At the end of March this year New Zealand and Australia received new standards and procedures for specimen collection, detection, and quantification of drugs in oral fluid - AS/NZS 4760:2019. Australia has always had the standard but it's a first for NZ.
This may add a easier and more viable way of testing for certain drugs other than requiring urine testing.
It may be a few months before accurate and reliable testing methods are developed and rolled out for the public, but it will happen.
FIRST Union was very quick to point out that when this happens companies who do not adopt this standard run the risk of breaching the Privacy Act. Quoting principal 4 of the Act: collection of information that is 'unreasonably intrusive' would be breached if a less intrusive method is viable.
The best way to ensure you are following best practice is to outsource your testing to a third party company who specialise in this area and ask them the questions around oral testing. If you do your own testing contact your training provider. At the very least you need to review your policies and particularly your references to the types of testing you may do.