Seriously...
Last year, in the early stages of the pandemic, I came down with fever and chills. I was sure I had Covid. I went and got tested. While the test wasn't hard at all... the waiting was. My wife and I take care of her mom and I couldn't afford to be sick. Luckily, I was fine - but the waiting was really hard.
Not exactly what you were looking for.... but I can't really think of a test that was difficult.