Posting for a friend

My friend and her his husband have been trying for a baby. Yesterday while he was at work me and her struck up the conversation about a pregnancy test. She had took one about 6 days ago, and it was negative.. but I've noticed a change in her. I told her I would go get her a test, so I went to a nearby family dollar

and got a 4$ pregnancy test.. she took it and there was an instant faint line, but i'm just wondering if cheap tests have false positives? I didn't get a picture of her test, but I found one on google that was the same brand and identical to hers. We calculated her to be due April 30, around 3-4 weeks I think? I'll post a picture of the test that looks similar, it's not her test, her line was faint, but it was there. The one i'm talking about is at the top. Have y'all had lines like that and was pregnant? Or is it a false positive? Hers came up probably 15-20 seconds after she dipped the test.. thanks in advance!