A friend of mine has code, which rebalances the classes of the test set before running the algorithm and calculating the accuracy. This causes the distribution of the two classes to be 50%/50% instead of 35%/65%. Is that problematic?
One class may be harder to predict than the other and when rebalancing the classes, it can change the test accuracy from the real accuracy. However, I'm not quite sure whether it's problematic and whether it would inflate/deflate accuracy?
EDIT: Tried to clarify my question based on comments.