typelevel / typelevel/scalacheck
retryUntil fails to produce anything when used to check list size inside a Prop
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Description
I'm not sure what to make of it:
scala> Prop.forAll(
arbitrary[List[Int]].retryUntil(_.nonEmpty)
)(_ => true).check
! Exception raised on property evaluation.
> Exception: org.scalacheck.Gen$RetryUntilException: retryUntil failed after 10001 attempts
org.scalacheck.Gen.loop$2(Gen.scala:131)
org.scalacheck.Gen.$anonfun$retryUntil$1(Gen.scala:135)
org.scalacheck.Gen$Parameters.useInitialSeed(Gen.scala:294)
org.scalacheck.Gen$$anon$3.doApply(Gen.scala:254)
org.scalacheck.Prop$.$anonfun$forAllShrink$1(Prop.scala:757)
From reading the scaladoc, it seems that .retryUntil should basically be the same as .suchThat for the purpose of using it in a Prop, except that it uses some internal filtering to circumvent the maxDiscardRatio. Am I wrong in thinking that?
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Research direction
Start by running the ScalaCheck snippet from the issue, then inspect Gen.scala around lines 131-135 and Prop.scala around line 757. Compare retryUntil with suchThat and trace how the generator is applied inside Prop.forAll. Done means the intended behavior is established and the reported failure is either corrected or clearly documented with regression coverage.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- scala
- Domain
- testing-qa
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 35/100