I have quit smoking for 15 days i have a saliva cotinine test in 2 weeks will i pass the test?

Yes: And you should stay quit. Even if you are doing the right thing for the wrong reasons, you have given yourself a head start in smoking cessation. You should keep that particular ball rolling and don't resume tobacco. Congrats on the decision - it's the single most important thing most smokers (if not all) can do for their overall health and survival.

Almost certainly: It's more important that you've stopped smoking. This is a wonderful gift that you've given yourself and those who love you.

Yes: “Nicotine & cotinine can take up to 4 days to be fully flushed from your saliva.” REF: https://www.healthline.com/health/quit-smoking/how-long-does-nicotine-stay-in-your-system#nicotine-inblood