add failing async test

[dignifiedquire]

I've been trying to use this module with async work, but if all emits are async this breaks down. Added a failing test to show the behaviour I mean.

This fails with

# through async
not ok 3 should be equivalent
  ---
    operator: deepEqual
    expected: [ 10, 20, 30 ]
    actual:   []
    at: pull (/Users/dignifiedquire/opensource/pull-through/index.js:46:22)
  ...

[dignifiedquire]

I'm not sure how far this is related with the Don't keep a reference to this, but I'm not seeing another way except for keeping a reference inside the writer when doing async work.

[dominictarr]

I mainly wrote this module to make porting a few other through node-stream modules easy.
one solution might be to make a pull-through2 which takes a callback?

can you describe the stream you are trying to implement?
you could prehaps also use asyncMap, and then flatten?

[dignifiedquire]

one solution might be to make a pull-through2 which takes a callback?

Yes that might be a possible solution. Maybe for now we just add note to the readme that this case is not working and asyncMap can be an alternative in those cases?

you could prehaps also use asyncMap, and then flatten?

Yes this is exactly what I ended up doing, switching to use asyncMap, as in my case I actually had a 1-1 mapping between in and out data.