Add custom equality matcher to support ES 2015 iterables

[kentaromiura]

Allows jest to check for equalities of Sets/Maps and Array-like by adding a custom equality tester for iterators.
Jasmine run custom equality before the normal equality checker, so I also add a test to ensure it didn't break normal Arrays equality (as they implement Symbol.iterator).

[cpojer]

Just call it iterators? :)

[cpojer]

Looks good overall but I added some code-style recommendations.

[cpojer]

actually, instead of using a while loop, can't you just use a for of loop? That way you'll avoid doing the manual iterator advancement for at least one of the iterators.

for (const value of a) {
  if (!matches) {
    return false;
  }
  bIterator.next();
}

[kentaromiura]

this is needed for the recursive check

[cpojer]

Looks great! Just a few minor comments – I recommend using the simplest possible solution to most things. You are unlikely to need some abstractions ever, so they just stay in the code until the end of time. It's better to pick the simple solution and extend it when needed :)

[kentaromiura]

@facebook-github-bot import

[facebook-github-bot]

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[github-actions]

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