Gen.between I think is the one I'm thinking of
On an unrelated subject, does anyone know why Arbitrary exists? I assumed because it does in QuickCheck, but in QuickCheck, it’s purpose is to aggregate Gen and Shrink, which I don’t think ScalaCheck does?
Exploring values on the other side of the interval’s “zero” feels like looking for a different failure symptom. But it can definitely be argued both ways, and it’s easy enough to implement sign swapping, so if you’d rather keep it for scenarios where zero is 0, the smallest positive failing test case is 123456789 and the smallest negative one -1, then I can definitely do that
Apologies in advance for the super vague question - still investigating.
We have some tests that were setting Seed(0) generating several instances of a fairly large generator.
After doing some rounds of upgrades (Scala 2.12 patch from 12 to 13), we noticed that the values generated are no longer the same.
So my question is - are all Seeds born equal? Could there be something special about our poor choice of seed 0?
Scalacheck is 1.14.0, but 1.15.4 has the same behaviour. I'm really clutching at straws here, everything else failed :)
(note that we don't use the generated values in a property, we just generate the values and compare them against a pre-defined set. It's not a good test.)
Yeah, this whole test is sadly an anti-pattern and we're trying to convert it, while attempting to understand what could possibly have affected it :D
@nikiforo This is one way to do it
property("genEntity") = {
val genEntity: Gen[List[Entity]] = {
for {
id <- Arbitrary.arbitrary[Int]
codes <- Gen.containerOf[Set,String](Arbitrary.arbitrary[String])
code <- codes.toList
} yield {
Entity(id, code)
}
}
Prop.forAllNoShrink(genEntity) { (entities: List[Entity]) =>
Prop.collect(entities.size) {
entities.size >= 0
}
}
}
Hi all,
Consider this code:
var seen = 0
var filtered = 0
private val genInt =
Arbitrary
.arbInt
.arbitrary
.map { v => seen += 1; v }
.filter(_ % 2 == 1)
.map { v => filtered += 1; v }
private implicit val arbInt: Arbitrary[Int] = Arbitrary(genInt)
test("uniqueGen") {
var listed = 0
check { ints: List[Int] =>
listed += ints.length
println(s"$seen/$filtered/$listed")
true
}
}running tests results in Gave up after 5 successful property evaluations. 51 evaluations were discarded.
And the logs are:
0/0/0
4/3/3
114/43/3
310/100/40/0/0
0/0/0
4/1/1
19/7/7
155/47/11From my POV this check should succeed, shoudn't it?
It should, but creating a collection (i.e. List) of Ints has a filter for size (see definition of
Gen.buildableOfN) and then your Gen[Int] has a filter for oddsthat causes ScalaCheck to exhaust the number of attempts. You might try retryUntil instead of filterbut that suggests a different implementation.
Actually the error message is from Scalatest, which has its own property checking implementation now, so my advice may be off, although I believe Scalatest property testing is similar to ScalaCheck.
Hi, I need to generate some random json sample, compliant to a schema supplied dynamically. Meaning that the input would be a schema (e.g. json-schema) and the output would be a json that complies to it.
So far i have no clue how to go about it. Hence I'm looking for pointers ? Any suggestion on this ?
So far i have no clue how to go about it. Hence I'm looking for pointers ? Any suggestion on this ?
4 replies
I just created a PR at typelevel/scalacheck#849, if anyone has any feedback that would be greatly appreciated
Hi, I have a third party lib that has its own random id
generateId method based on instance of Random. I want to create a generator that produces valid values using that method. But as far as I can see all access to constructors is private in Gen, so I wonder how can I create that one (I will need to access Seed to provide Random based on it to the generateId method)?
8 replies