IssueTracker

Component used: Room, Lifecycle, Arch Core, Kotlin Coroutines
Version used: Room 2.1.0, Lifecycle 2.2.0-alpha01, Arch Core 2.1.0-beta01
Devices/Android versions reproduced on: Emulator API 28

The following test won't run, when I use a suspended 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) // Comment #1
        }
    }

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

        assertThat(recurringEntry, notNullValue())

        RecurrenceManager.insertRecurrencesAndSchedule(ApplicationProvider.getApplicationContext(), db, recurringEntry!!) // Comment #3

        val bookEntries = db.bookEntryDao().getBookEntries().liveDataValue() // Comment #4
    }
}

This is the function at #1, and also in #3:

@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
}

It looks like the insert function at #1 causes the test running an infinite loop.
Code at #2 is never reached.

I figured out, that when removing the InstantTaskExecutorRule, the test runs correctly until #4.
There, I try to fetch the database items from LiveData using the method from googlesamples:
https://github.com/googlesamples/android-architecture-components/blob/master/GithubBrowserSample/app/src/test-common/java/com/android/example/github/util/LiveDataTestUtil.kt

When reaching #4, the error " java.lang.IllegalStateException: Cannot invoke observeForever on a background thread" is thrown.