Re:There are only four billion floats, so test them all (2014)
by kortilla on Tuesday October 13, 2020 @07:17PM
(#24771432)
That’s not useful. A swapped out hashing algorithm would have been proving the same thing and would have allowed you to test important things like 3+ collisions and two sets of collisions.
Anyone who demanded the real hashing algorithm in this case doesn’t understand how hash collisions work and what problems you need to solve when using hashing. Your “100% accurate test case” serves very little value.
It’s the same as requiring a real person perform the checkout workflow in your shopping cart integration tests. It’s “100% accurate” but it’s a massive waste of resources and provides terrible coverage of the many other edge cases.
Re:There are only four billion floats, so test them all (2014)
by Scarblac on Sunday October 11, 2020 @03:35PM
(#24748413)
It ensures that if someone changes the hashing algorithm, your test for the collision mitigation now doesn't test that anymore even though they should be unrelated.
Re:There are only four billion floats, so test them all (2014)
by halter73 on Sunday October 11, 2020 @06:20PM
(#24749601)
After going through all that effort to make the test less "fake", I expect tialaramex verified the collision still happened as part of the test.
Re:There are only four billion floats, so test them all (2014)
by tialaramex on Sunday October 11, 2020 @09:11PM
(#24750550)
Yes, actually we also verified that all the hashes were exactly what we expected, because we were using this for content based addressing. "The hash has unexpectedly changed" was a fatal build error.
If we wanted to change how the hash is calculated all extant instances of the system need to dump to backups, then be painstakingly restored after updating. Possible, but certainly not something you'd be doing for giggles.
Also I can employ a $75k - $100k/year engineer and say follow this protocol for testing. If I want someone who can optimize test case 100% of the time with zero mistakes ever then I might have to pay $150k - $200k / year.