As long as you are applying CBD topicals externally, you should not fail a drug test. Because topicals are administered to the skin, they will not enter your bloodstream or produce a high. This can be compared to rubbing alcohol on your skin to cleanse the area; skin contact with rubbing alcohol won't intoxicate you because it doesn't enter the bloodstream and the same can be said for CBD topicals. With that said, most drug tests will be looking for cannabinoid THC, not CBD.
Here are a couple articles with more information you may find helpful - Can Taking CBD Cause Me to Fail a Drug Test?: https://www.hellomd.com/health-wellness/574b679b982db9000a000055/do-cannabis-topicals-pass-the-drug-test
Do Cannabis Topicals Pass the Drug Test?: https://www.hellomd.com/health-wellness/574b679b982db9000a000055/do-cannabis-topicals-pass-the-drug-test
I hope this information helps! :-)