The TestScope advanced example of usage in tests with coroutines

Issue

Could someone provide an advanced example of using the new TestScope and TestScope.launch while testing with coroutines?

It seems like in the new kotlinx.coroutines.test release they've added somewhat called TestScope to the library. Also, they've deprecated the old TestCoroutineDispatcher and told to use TestScope.runTests instead, however, they didn't add much documentation on how to use it. Everything I could find is this.

Can anyone provide me with some extra examples of usage in different scenarios?

Solution

I could also fix this problem with @Joffrey mentioned at the comment. You only need to use runTest { } to use coroutine scope at the test code. By using runTest { } you can use TestScope inside the block with this.

In my case, there was a flow function at the viewModel something like this. It was running inside the viewModelScope.

    fun getFriendDataWithFlow() {
        viewModelScope.launch {
            repository.loadFriendsWithFlow()
            ...
        }
     }

And I should test this at my test code, and I used it like this.

   @ExperimentalCoroutinesApi
   @Before
   fun setup() {
       Dispatchers.setMain(StandardTestDispatcher())
   }

   @ExperimentalCoroutinesApi
   @Test
   fun temp() {
        runTest {
            viewModel.getFriendDataWithFlow()
        }
   }

All I did was add runTest { } block, and add coroutine code inside the block. And it worked for me. My test coroutine dependency was "org.jetbrains.kotlinx:kotlinx-coroutines-test:1.6.0-RC".

Answered By - Lee WonJoong