Will your driving test be cancelled due to snow?

If the roads have been salted and are reasonably clear, then the test will likely go ahead. If there is snow covering quieter residential streets, or country roads, the test may be cancelled. The driving examiner also checks the roads due to frost.
The Test Centres main priority with every driving test is the safety of both the learner driver candidate and the examiner, which is why they won’t have you taking your test if the road conditions are unsafe. If they can, they’ll allow tests to continue on the least affected routes.  They’ll also keep a close eye on the weather forecast to make informed decisions.