force sample to return Some(Value) instead of None

[nykolaslima]

I'm using Scalacheck to define objects that will be used in my unit tests.

val listingGen = for {
    id <- posNum[Long]
    name <- alphaStr
} yield Listing(id, name)

//I want that listingGen always return me a Listing
listingGen.sample.get

the listingGen.sample could return None. How can I force scalacheck to return me Some(Listing)?

[rickynils]

In the general case, you can't. ScalaCheck generators can fail, for instance if you're adding a filter (listingGen.suchThat(...)), and that failure is modeled with the Option type. However, if you're sure that your generator never will fail, you can simply call Option.get like you do in your example above. Or you can use Option.getOrElse to replace None with a default value.

If you know that your generator might fail, but very seldomly, you can use Gen.retryUntil(_ => true). This will simply re-run a generator if it fails. You should be careful with this, since you might end up in a non-terminating loop, though.

[SethTisue]

sounds like this should just be closed?

[non]

👍