To test code in doStuff just test this function do not test

Question

To test code in doStuff just test this function do not test myMethod

aaverin · Answer

`doStuff ` is private Would you recommend to move to another class and have just a `manager` kind of class that will run coroutine in proper dispatcher and do nothing else

gildor · Answer

I recommend to expose suspend functions as public API instead of non suspend functions that wrap them to launch or any other coroutine builder

aaverin · Answer

So basically all coroutine run methods should be public to be testable without coroutines

aaverin · Answer

That really depends on the kind of class For this particular one I want it to manage `job` and handle cancelation if necessary thus it s not exposed as `suspend`

gildor · Answer

I would think about in a little bit different way Most of API that use coroutines should be suspend functions such functions easy to test and user of this API can do anything what he want wrap to GlobalScope launch or run them in parallel in local scope

gildor · Answer

Main problem of `myMethod` that you do not return Job

gildor · Answer

so cannot join and don t know when function is finished

gildor · Answer

this is programming with side effect that even cannot be checked properly

gildor · Answer

and just use GlobalScope probably bad idea in this case

gildor · Answer

I don t know exactly your case but most probably there are some more clean ways to encapsulate lifecycle of `doStuff` than just GlobalScope launch and a function that runs and forget

gildor · Answer

If you want example with Rx it s the same reasoning when you expose Observable Single correct way same as suspend function or hide it in a function that returns nothing so it s hard to test and you cannot control lifecycle or integrate to existing Rx code This is exactly the same case with susepnd function good and global launch bad

gildor · Answer

Returning Job is little bit better but still I would use suspend function same way as in Rx better to return Observable Single instead of just Disposable

gildor · Answer

gt Would you recommend to move to another class and have just a `manager` kind of class that will run coroutine in proper dispatcher and do nothing else Actually this is one of possible solutions but even in this case probably it can be somehow improved

aaverin · Answer

So speaking in Android context if I keep making all functions `suspend` then essentially only Activity Fragment would be using dispatchers and would be running coroutines

aaverin · Answer

That would be exposing all jobs subscription management to Activity Fragment that is bound to lifecycle and needs to handle rotation and other kinds of events

aaverin · Answer

with Rx we were trying to avoid that cutting subscription in UseCase or in Presenter directly

aaverin · Answer

We could keep this in Presenter then it would be this `manager` class

aaverin · Answer

That is essentially what we did on backend only Controllers start coroutines and in some special cases that is `withContext` for services that have to definitely run in background like 3rd party API calls

aaverin · Answer

Just thinking how to properly structure that for Android too

gildor · Answer

If you want hide it from Activity no problem just hide it use another top level wrapper it s not neccessary should be Activity Fragment I just mean that it s hard to test such code because you actually can only test side effects not real functions This imo looks more like integration testing than unit And yeah probably in this case make sense to provide different dispatcher and use it

gildor · Answer

I don t think that Rx approach somehow different in terms of architecture

aaverin · Answer

Well With Rx there is `subscribeOn` and `observeOn` and once you get the description of those methods it s quite easy to see which thread code will be called on and which thread will subscriber receive the data on With coroutines it s not that easy somehow

gildor · Answer

But this is exactly the same You have suspend function that doesn t have any particular thread and call it from coroutine in particular thread