> one day, the generator violates those unstated constraints, causing the test to fail Good, that's exactly the sort of assumption I'd like to have exposed. As

> one day, the generator violates those unstated constraints, causing the test to fail Good, that's exactly the sort of assumption I'd like to have exposed. As a bonus, we only need to can fix this in the generators, and all the tests will benefit. I've hit exactly this sort of issue with overflow before, where I made the mistaken assumption that 'n.abs' would be non-negative. In this case Scalacheck will actually start off generating small/empty strings, and try longer and longer strings up to length 100. This is because 'arbitrary[String]' uses 'Gen.stringOf': https://github.com/typelevel/scalacheck/blob/master/src/main/scala/org/scalacheck/Arbitrary.scala#L148 https://github.com/typelevel/scalacheck/blob/master/src/main... 'Gen.stringOf' uses the generator's current "size" parameter for the length: https://github.com/typelevel/scalacheck/blob/master/src/main/scala/org/scalacheck/Gen.scala#L913 https://github.com/typelevel/scalacheck/blob/master/src/main... https://github.com/typelevel/scalacheck/blob/master/src/main/scala/org/scalacheck/Gen.scala#L1254 https://github.com/typelevel/scalacheck/blob/master/src/main... The "size" of a generator starts at 'minSize' and grows to 'maxSize' as tests are performed (this ensures we check "small" values first, although generators are free to ignore the size if they like): https://github.com/typelevel/scalacheck/blob/master/src/main/scala/org/scalacheck/Gen.scala#L275 https://github.com/typelevel/scalacheck/blob/master/src/main... We can set these manually, e.g. via a config file or commandline args, but the default is minSize = 0 https://github.com/typelevel/scalacheck/blob/master/src/main/scala/org/scalacheck/Test.scala#L198 https://github.com/typelevel/scalacheck/blob/master/src/main... and maxSize = 100 https://github.com/typelevel/scalacheck/blob/master/src/main/scala/org/scalacheck/Test.scala#L199 https://github.com/typelevel/scalacheck/blob/master/src/main... https://github.com/typelevel/scalacheck/blob/master/src/main/scala/org/scalacheck/Gen.scala#L338 https://github.com/typelevel/scalacheck/blob/master/src/main...