Harder than it should be, IMO.
The testing needs to be in the upstream. It shouldn't be a mess of afterthought and duplicated effort on the part of distributions. Your upstream is probably going to be better at it anyway having the benefit of being intimately familiar with the code and being the recipient of much broader feedback than any one distribution alone.
Again we see the reoccurring wisdom of being part of your upstream as much as possible.
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