Snorting coke isn't a risk for HIV contraction. Sharing straw, rolled up note or whatever mixed with infected fluid doesn't put you at a risk for HIV contraction. Only risky situation would be to inject heroine or other drugs intravenously by sharing needles with people of questionable serostatus.
However just a word of advice, cocaine abuse can lead to serious cardiovascular and psychological complications in longer run.
No risk for HIV contraction, testing won't be necessary.