CODEWITHSUNDEEP
androidrx-java2android-room
Piotr Aleksander Chmielowski
Piotr Aleksander Chmielowski

Reputation: 6432

Subscriber of Room's DAO method returning Flowable is not notified about inserted entities

I have a Room database with one entity and DAO, which allows inserting objects and observing SELECT query as Flowable. When I subscribe to this Flowable and, then, insert a new object to database, new results are not emmited.

@Database(entities = [User::class], version = 1)
abstract class TestDatabase : RoomDatabase() {
    abstract val dao: UserDao
}

@Dao
interface UserDao {
    @Insert
    fun insert(user: User)

    @Query("SELECT * FROM User")
    fun observeUsers(): Flowable<List<User>>
}

@Entity
data class User(@PrimaryKey val id: Int, val name: String)

A failing test:

@RunWith(AndroidJUnit4::class)
class ObserveUsersTest {

    @Test
    fun observeUsersTest() {
        val db = Room.inMemoryDatabaseBuilder(
            InstrumentationRegistry.getContext(), TestDatabase::class.java
        ).build()
        val dao = db.dao
        val user = User(0, "George")
        val test = dao.observeUsers().test()

        dao.insert(user)
        test.assertValue(listOf(user))

        db.close()
    }
}

The failure:

java.lang.AssertionError: Expected: [User(id=0, name=George)] (class: SingletonList), Actual: [] (latch = 1, values = 0, errors = 0, completions = 0)

Test passes if inserting is done before calling to observeUsers:

    dao.insert(user)
    dao.observeUsers().test().assertValue(listOf(user))

What am I doing wrong?

Upvotes: 0

Views: 207

Answers (1)

akarnokd
akarnokd

Reputation: 69997

I'd guess you don't wait long enough to observe the result of the insertion. If insert is asynchronous internally (even though you didn't define it with an RxJava API), you could be subscribing and testing for a single value too early.

Try using the awaitCount tester-method before asserting a single value (as you have a infinite Flowable so awaitTerminalEvent doesn't work of course):

dao.observeUsers()
.test()
.awaitCount(1, TestWaitStrategy.SLEEP_10MS, 5000)
.assertValue(listOf(user));

Upvotes: 2

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