I had two friends that were given urine tests in Kaohsiung. The tests came back positive. They went to court and had to serve two weeks in a “rehabilitation” facility. If I had been your friend I would have refused the urine test until I talked to someone from his “Embassy”. I think that there are no implied consent rules for urine tests.
I wonder if it is possible to leave the country with a urine test pending?
The two weeks my friends served were hell. In a small room with five other people. No curtains for privacy, not even around the squat toilet or the shower.
Actually another friend was given a urine test, it came back positive. She is rich and hired an attorney who challenged the positive result three times and eventually, the court let her go.