On Mon, Jan 18, 2010 at 2:00 PM, Drew Farris <drew.far...@gmail.com> wrote: > In what cases would you want to reset them all remotely, at the > beginning of each test?
You pretty much said it -- tests should start from a known, fixed state, so that the result is the same each time, and we can assert about the output. This means setting the entire library and test fixture state to a known state -- that's why there's a need to not just control the initial seed but reset it. (Separately you could argue we're going about this all wrong, by trying to depend on the exact output of the RNG, and should be writing tests that assert only what's true no matter what the outcome, or else, assert things that should be true in 99.9999% of all RNG sequences. But let's resort to that argument later.) > In tests you call > > Random r = RandomUtil.getTestRandom() > ev = new GenericRecommenderIRStatsEvaluator(r); > > In production code you call: > > Random r = RandomUtil.getRandom(); > ev = new GenericRecommenderIRStatsEvaluator(r); And you're suggesting getRandom() returns a randomly-seeded RNG? Then this just returns to the original problem: the test is not repeatable. You've moved around the injection, but nothing else I think. Am I misunderstanding because that seems to be why I'm not following getTestRandom(). (Taking it as a constructor param is the conventional way to set up for injecting, but from an API perspective I don't quite like it. I understand why an evaluator necessarily needs a Recommender to exist, but why do I need to give it a Random, conceptually?)
