Single.zip with Iterable<T> overload does not call given zipper function

[SergejIsbrecht]

I have discovered that, invoking Single.zip with an empty Iterable will not call given zipper function. Is this behavior by design? I would expect that the zipper function would be called with an empty object-array.

  @Test
  void singleDoesNothing() {
    Single<Object[]> zip =
        Single.zip(
            Collections.emptyList(),
            objects -> {
              return objects;
            });

    zip.test().assertNotComplete().assertNoValues();
  }

Used version: 2.1.7

[akarnokd]

Yes, this is by design.

[yuriykulikov]

Hello David,
could you please elaborate? What is the reason for this?

[akarnokd]

0 sources have no items to zip.

[yuriykulikov]

It must be at least explicitely mentioned in the documentation. Otherwise there is a lot of confusion, because developers interpret the current javadoc as: "empty Iterable -> empty Array". This is very unfortunate, because an empty Iterable becomes a corner case, which does not always happen, but when it does, nothing happens.

[akarnokd]

See #5876.

[artem-zinnatullin]

Guess we could close this as #5876 was merged :)