Intermittent failure in Scalacheck suite (scalacheck/duration.scala)

[retronym]

Thanks to @rorygraves for this report:

Looking at the test failure - its unrelated

[info] ! Division of Duration by Long.on overflow edge cases: Exception raised on property evaluation.
[info] > Exception: org.scalacheck.Gen$Choose$IllegalBoundsError: invalid bounds: low=9223372036854775799, high=-9223372036854775797

I did some investigation and the failure occurs here

A value of 1 or -1 fails the choose on line 35.
I don't have time to raise the proper bug report right now - but thought I would highlight it.

[Ichoran]

It's a very strange way to choose an interval anyway. A trivial fix would be to change the instances of Long.MaxValue to (Long.MaxValue - 10) or just to change - 10 and + 10 to - 20 and + 0. But I haven't dug enough to understand the point of the code so I'm hesitant to recommend it.

[l0rinc]

Isn't the problem an overflow for very small a, i.e.Long.MaxValue / 1 + 10?

[rorygraves]

@paplorinc As far as I can see it only fails for 1 and -1 - We could:

• Exclude -1 and 1 (we exclude 0 already)
• Follow @Ichoran suggestion and you -20 and 0 rather than -10,+10
• Sort the two values to make choice accept them.
  I don't have a strong opinion - I'm happy to PR a version once we are happy with which approach to take.

[SethTisue]

seen again today at https://scala-ci.typesafe.com/job/scala-2.12.x-validate-test/4124/consoleFull

[SethTisue]

and at scala/scala#5592

this has been so common lately, it makes me wonder whether a ScalaCheck failure even failed the build before scala/scala#5661. (not that it matters now, just idle curiosity)