Also on 2019 on Android Dev Summit '19 said that we should ALWAYS inject Dispatchers to make the dispatcher different from production as in the unit test. Is still like this?

it’s an opinion. It’s indeed good advice in general, but you pay for it by more complex set up and additional code

Totally agree. If you don't inject, what do you do on Test?

what do you mean “what do you do on test”?

So if I inject the

TestCoroutineScope

and the

TestcoroutineDispatcher

i don't need to use the

Dispatchers.setMain(TestCoroutineDispatcher())

and

Dispatchers.resetMain()

right? Because I'm setting it on my constructor

yes

I see, because I was creating a rule for testing, but then what you are saying to me now is that if I create this

TestCoroutineScope

and

TestCoroutineDispatcher

via constructor on my rule I don't need this

@Beforeall
fun setUp(){
Dispatchers.setMain(TestCoroutineDispatcher())
}

@afterEach
fun afterEach(){
testScope.cleanUpTestCoroutines()
}

@AfterAll
fun tearDown(){
Dispatchers.resetMain()
}

you also can do testScope.context[CoroutineDispatcher]!!

But my question is, does it really need a Rule for this? If I'm injecting the

CoroutineScope

and the

CoroutineDispatcher

does it helps? No, right? I mean, if I do inject, and in the test create the

TestCoroutineScope

and the

TestCoroutineDispatcher

and create the presenter on this case passing that as a parameter, I don't need anything else, right? Or do I have to

cleanUpTestCoroutines()

in the

tearDown

? What I mean is, I created the Rule but now that you've explained to me that

Dispatchers.setMain(..)

and

Dispatchers.resetMain()

doesn't change the

IO

it's not necessary to do it anymore, even if I'm creating the

TestCoroutineDispatcher

right? So when creating the test I just need, create these

TestCoroutineX

and that's it?

rule is really useful to replace main dispatcher, if you inject it, I don’t see reason to have a rule and would just use runBlockingTest

And last question, is it necessary to

cleanupTestCoroutines()

?

This checks ensures that no coroutines are running on test scope (which may be a bug), runBlockingTest does this automatically after lambda is invoked

Awesome, thanks Andrey 😉

Night 🛏️ 😄