conditional property doc example about scalacheck

[Philippus]

1. I think it's because of the n >= 0 part in propMakeList.
   ScalaCheck has a bias for special values (like 0 and 1).
   Probably in this case the values 0 and 1 are selected enough times for 100 successful tests.

If you change your x > 0 to x >=0 you will also get 100 successful tests (but mainly 0 and 1 will be tested).

You can play around with collect to see the distribution of the generated data:

  val propMakeList = forAll { n: Int =>
    collect(n) {
      (n >= 0 && n < 10000) ==> (List.fill(n)("").length == n)
    }
  }

(This also means that the example given in the documentation is a little unfortunate as the property is only really tested for values 0 and 1.)

2. yes, I think so.

[ashawley]

That's correct. The example uses fencing so it is a fragile test. The tutorial now includes information about discarded generated values.