How to write a @ParametrizedTest with two parameters with filtered values?

Question

Consider my test class:

public class TestClass {

    static public class Vegetable {
         String name

         public Vegetable(String name) { ... }
    }

    static public class Fruit {
        String name;
        List<Vegetable> assignedVegs;

        public Fruit(String name, List<Vegetable> vegs) { ... }
    }

    List<Fruit> fruits = asList(
        new Fruit("Orange", asList(new Vegetable("Potato"))),
        new Fruit("Apple", asList(new Vegetable("Potato"), new Vegetable("Carot")))
    );         

    @ParametrizedTest
    public void test(Fruit f, Vegetable v) { ... }
}

I would like to run my test method with the following data combinations

• ["Orange", "Potato"],
• ["Apple", "Potato"],
• ["Apple", "Carot"],

however, without adding further elements to fruits or changing the signature of test . What is the best way to achieve this using for example a @MethodSource ? Or is there any more junit-like way to achieve a similar result? And what would be the approach if the parameter space was even higher dimensional?

Answer 1

Yes, it works indeed with a @MethodSource using lambdas:

private static Stream<Arguments> testDataProvider() {
    List<Arguments> testCases = new ArrayList<>();

    fruits.forEach(fruit -> {
        fruit.assignedVegs.forEach(veg -> {
            testCases.add(Arguments.of(fruit, veg));
        });
    });

    return testCases.stream();
}

For higher dimensions it's engough to nest further .forEach s