How to make the property test get a collection of entities an entity-generator can return?

Question

I have recently started exploring property based testing using junit-quickcheck. I came across an usecase where a property has to take a list of entities(I have a generator for a standalone entity). I have tried with the code below and it always gives an empty list.

@Property(trials = 5)
  public void addingInDiffOrderResultsInSameResult(
      List<@From(CusObjGen.class) CusObj> objs) {
}

Can someone show some right way here?

Answer 1

I got it worked by creating another generator that generates list of entities using the entity-generator that was already present like this:

public class CusObjListGenerator extends Generator<List> {

  public CusObjListGenerator () {
    super(List.class);
  }

  @Override
  public List<CusObj> generate(SourceOfRandomness random, GenerationStatus status) {
    CusObjGen generator = gen().make(CusObjGen.class);
    List<CusObj> objs = new ArrayList<>();
    int randomNoOfEvents = random.nextInt(1, 15);
    for (int i = 1; i <= randomNoOfEvents; i++) {
      objs.add(generator.generate(random, status));
    }
    return objs;
  }
}