Fix test issue as reported in #195

[nordfjord]

The issue came about because the test is asynchronous but wasn't
supplied a done callback.

This lead to a swallowed error.

This commit fixes the test such that it gives the expected result and
calls the done callback

[coveralls]

Coverage remained the same at 100.0% when pulling 35cb544 on fix/chain-test into 180e8f5 on master.

[coveralls]

Coverage remained the same at 100.0% when pulling 3e3dfca on fix/chain-test into 180e8f5 on master.

[coveralls]

Coverage remained the same at 100.0% when pulling 35cb544 on fix/chain-test into 180e8f5 on master.

[StreetStrider]

From my perspective, done callback is a mess and it's not unusual to forget it.

I always settle my system, defining something like drain(Stream<T>) → Promise<T>, then making all tests async and return drain(s) from them, where s is (in some sence) considered main instance of that test.

When I need series of values, I use concat(Stream<T>) → Promise<T[]> with similar approach: expect(await concat(s)).eq(sequence) (in async test).

[nordfjord]

@StreetStrider I do believe the test framework and eslint settings are due for an overhaul.

For instance the tests fail if I use arrow functions as that's not permissible by the es version.

With that in mind, how would you change the test?

[StreetStrider]

@nordfjord with that in mind, my strategy still can be applied. Before async/await and arrows I'd just used function () { … } and return promise. mocha supports this, while async/await and arrows can be used as sugar.

[nordfjord]

@StreetStrider I've updated the PR returning a Promise instead of using done

[StreetStrider]

Looks good.