I have a friend that thinks she may be pregnant but doesn't want to take a test because she thinks that since she's on the pill it will effect the result. I know the tests check for HCG levels, but will being on the pill effect the test?

No, birth control pills won't effect a pregnancy test result. Have her test so she can know if she needs to stop using the pill or not.

To add to what Doula said, the pill does not contain HCG, so it will not effect the results of the test.