According to Beny, the lab owner, they are PCR tests with the nasal swab. And as I mentioned before she bought them in in response to the Canadian Government's declaration / rules knowing full well that people will need them.

Her lab is one of the best in the region, she is very highly trained and respected around here.

As for documentation required I cannot answer that. I have no plans of leaving Mexico any time soon (I have only left the country 4 times in the last 17 years) so I was just passing on the information as I know a lot of people want it and will need it.