Here's the usual and very broad meaning/ Was it ever in doubt that you would pass? The speaker usually expects an answer meaning 'No, everyone always thought I would pass'.
Was it ever in doubt that you would not pass? The speaker usually expects an answer meaning 'N
This seems to me, at least, to be a contradiction of the general purpose of a double negative. For example 'doubt'and 'wouldn't' are both negative words. In maths a double negative equals a positive. There the answer to the question is 'no there was no doubt.' I don't know what these other people are saying but they appear to me to be wrong.