Android instrumentation test doesn't run to end when using Room @Transaction function

Question

I'm testing with AS 3.4.1 and Emulator running Android 9.

The following test won't run, when I use a Room Dao Function annotated with @Transaction in it.

class RecurrenceManagerTest : DatabaseTest() {

    @Rule
    @JvmField
    val instantTaskExecutorRule = InstantTaskExecutorRule()

    var recurringEntryId: Long = -1

    @Before
    override fun setup() {
        super.setup() // only initialized the db

        val recurringEntry = RecurringEntry(
            recurrence = Recurrence(DATE.toEpochMilli(), Recurrence.DAILY)
        )

        recurringEntryId = runBlocking { db.recurringEntryDao().insert(recurringEntry) }

        val recurringBookEntry = BookEntry.create(
            title = TITLE,
            date = DATE,
            value = VALUE,
            isPaid = IS_PAID,
            notes = NOTES,
            entryType = ENTRY_TYPE,
            categoryId = CATEGORY_ID,
            contacts = CONTACTS,
            recurringEntryId = recurringEntryId
        )

        runBlocking {
            db.bookEntryDao().insert(recurringBookEntry) // BreakPoint #1
        }
    }

    @Test
    fun testInsertRecurrencesAndSchedule() { 
        var recurringEntry = runBlocking { db.recurringEntryDao().get(recurringEntryId) } // BreakPoint #2

        assertThat(recurringEntry, notNullValue())

        runBlocking { RecurrenceManager.insertRecurrencesAndSchedule(ApplicationProvider.getApplicationContext(), db, recurringEntry!!) }

        val bookEntries = db.bookEntryDao().getBookEntries().liveDataValue()
    }
}

This is the function for inserting:

@Transaction
suspend fun insert(bookEntry: BookEntry): Long {
    val id = insert(bookEntry.entity)
    bookEntry.embeddedContacts?.apply {
        forEach {
            it.id = 0
            it.bookEntryId = id
        }
    }?.let {
        insert(it)
    }

    return id
}

So if I'm running the test like it is (see BreakPoint #1), BreakPoint #2 won't even be called, so the test ends somewhere before, without a result.

If I'm replacing the code at BreakPoint #1 with exact the same code, the insert function has, the test runs correctly.

Does anyone have an idea what's the issue here?

Lionize

That's because you are assering without the runblocking has finished – Kordofanian

@Stavro Xhardha I thought runblocking waits until the body has finished? Any way to solve this? – Lionize

well I don't really know the way you are using. But check my post on the last section I am testing a room insert and select. check this – Kordofanian

Answers on this related question by me suggest that this is not possible, at the moment :( #57028350 – Agata

Answer 1

You can use setTransactionExecutor to run transaction in another thread

return Room
       .inMemoryDatabaseBuilder(context, MyRoomDatabase::class.java)
       .setTransactionExecutor(Executors.newSingleThreadExecutor())
       .build()

then while testing use runBlocking instead of runBlockingTest

@Test
fun moveItem() = runBlocking {
    transactionFunction()
}

Atomicity

Great! For users of kotlinx.coroutines 1.6.0: also works with runTest – Contradictory

Answer 2

I faced the same issue and the problem was because of the InstantTaskExecutorRule, if you remove the below block of code the @Transaction should work fine with the suspend keyword

@Rule
@JvmField
val instantTaskExecutorRule = InstantTaskExecutorRule()

It seems that this rule blocks the RoomDatabase from acquiring the transaction thread. In RoomDatabase.kt execution gets blocked in the below function:

private suspend fun Executor.acquireTransactionThread(controlJob: Job): ContinuationInterceptor

Hope this helps!

Aubree

Well, the test runs now, but I need the InstantTaskExecutorRule for the liveDataValue() method, because after removing this line, an error is thrown: java.lang.IllegalStateException: Cannot invoke observeForever on a background thread. – Lionize

How did you get it working with InstantTaskExecutorRule ? – Aubree

The test runs, after removing InstantTaskExecutorRule, but now I've an error with observeForever. – Lionize

My .liveDataValue() extension function is a copy of this one: github.com/googlesamples/android-architecture-components/blob/… – Lionize

Is there a possibility to test LiveData + Coroutines? – Lionize

I not sure to be honest. But I wasn't able to get it working – Aubree