Add method to Arguments for getting payloads

[onacit]

Say, I have the following methods.

    class Some {

        static Stream<Arguments> getNameAndAgeArgumentsStream() {
            return Stream.of(
                    Arguments.of(
                            Named.of("Whatever", "John"), // <<<<<<<<<<<<<<<<<
                            1
                    );
        }
    }

    class Other {

        static Stream<Arguments> getNameAndAgeArgumentsStream() {
            return Stream.of(
                    Arguments.of(
                            "Jane",  // <<<<<<<<<<<<<<<<<<<<<<<
                            1
                    );
        }
    }

Now I want to use those two methods in other class.

    class Another {

        static Stream<Arguments> getPrefixedNameAndAgeArguemntsStream() {
            return Stream.concat(
                            Some.getNameAndAgeArgumentsStream(),
                            Other.getNameAndAgeArgumentsStream()
                    )
                    .map(a -> {
                        var arguments = a.get();
                        var name = arguments[0] instanceof Named ? ((Named<String>) arguments[0]).getPayload() : arguments[0];
                        return Arguments.of(
                                "prefix" + name,
                                arguments[1]
                        );
                    });
        }
    }

I had to use a method looks like this.

    public static <T> T payload(final Object argument) {
        Objects.requireNonNull(argument, "argument is null");
        if (argument instanceof Named<?>) {
            return payload(((Named<?>) argument).getPayload());
        }
        return (T) argument;
    }

Deliverables

• Add a method returns ultimate payload values from an Arguments, say, getPayloads()[Ljava.lang.Object

[marcphilipp]

This is what we currently do to unwrap Named arguments:

https://github.com/junit-team/junit5/blob/12bccfd63ba2cf8d9f593f90c1343835dd56add3/junit-jupiter-params/src/main/java/org/junit/jupiter/params/ParameterizedTestParameterResolver.java#L121-L130

I think we could expose that as a static Object[] Named.unwrap(Object[]) method on Named.

@onacit Would that be sufficient for you?

[onacit]

@marcphilipp That's great! Thank you.

• Don't we have, you know, a Named<?> wraps another Named<?>?

If I may, let me share what I've done.

    // _Named_TestUtils.java
    public static <T> T payload(final Object argument) {
        Objects.requireNonNull(argument, "argument is null");
        if (argument instanceof Named<?>) {
            return payload( // <<<<<<<<<<< peel it off until it's not a `Named<?>` anymore
                    ((Named<?>) argument).getPayload()
            );
        }
        @SuppressWarnings({"unchecked"})
        final var cast = (T) argument;
        return cast;
    }

    // _Arguments_TestUtils.java
    public static Arguments ofPayloadsMapped(final Arguments arguments,
                                             final IntFunction<? extends Function<Object, Object>> mapper) {
        Objects.requireNonNull(arguments, "arguments is null");
        final var got = arguments.get();
        return Arguments.of(
                IntStream.range(0, got.length)
                        .mapToObj(i -> mapper.apply(i).apply(_Named_TestUtils.payload(got[i])))
                        .toArray()
        );
    }

    public static Arguments ofPayloads(final Arguments arguments) {
        return ofPayloadsMapped(arguments, i -> Function.identity());
    }

    // may gone to far, but worth it!
    static Stream<Arguments> getCipherAndParamsArgumentsStream() {
        return Stream.concat(
                JinahyaBlockCipherUtils_AES_Test.getCipherAndParamsArgumentsStream(),
                JinahyaBlockCipherUtils_ARIA_Test.getCipherAndParamsArgumentsStream()
        ).map(a -> _Arguments_TestUtils.ofPayloadsMapped( // peel off while remapping into, say, another `Named<?>`
                a,
                i -> p -> switch (i) {
                    case 0 -> _BufferedBlockCipher_TestUtils.named(new CTSBlockCipher((BlockCipher) p));
                    case 1 -> _KeyParameters_TestUtils.named((KeyParameter) p);
                    default -> p;
                }
        ));
    }

[marcphilipp]

When would Named be wrapping an argument multiple times?

[onacit]

When would Named be wrapping an argument multiple times?

You're right. Thanks.

[marcphilipp]

Why did you close the issue? Don't you want the method I suggested in #4144 (comment) to be added?