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Hey, I am trying to test Android room Dao function that returns a PagingSource. But following the docs, the test runs indefinitely. Check the following snippet:

```val expectedData = listOf(area)

val expected = PagingSource.LoadResult.Page(
    data = expectedData,
    prevKey = null,
    nextKey = 1
)

val actual = globalAreaDao.fetchPagedGlobalAreas("%a%").load(
    PagingSource.LoadParams.Refresh(
        key = null,
        loadSize = 2,
        placeholdersEnabled = false
    )
)
Truth.assertThat(expected).isEqualTo(actual)```


Is this the right way to test dao functions that return a `PagingSource` object?

is this using room - paging artifact ? (in 2.4)
not sure why that is not working, cc: <@U2245FK37>

Yes, I have finally resolved this. I had `InstantTaskExecutorRule` which caused the load function not return. Also, it fails using `runBlockingTest` on the `mainCoroutineRule`   but works for `runBlocking`.

I'm running into the same issue with PagingSource `load` function not returning. This after updating to Room 2.4 (2.3 works fine). I had to @Ignore some existing tests. I tried above :point_up: solution but no luck so far.

On the dev comments <https://android.googlesource.com/platform/frameworks/support/+/b0897a44f5ecc1bbfb66be98fccf03ef77bc5d90>

```"The PagingSource implementation generated by room-paging now
  uses the queryExecutor passed through RoomDatabase.Builder, so it can
  be overridden, instead of <http://Dispatchers.IO|Dispatchers.IO> previously."```
I had to change the _executor_ back to `<http://Dispatchers.IO|Dispatchers.IO>.asExecutor()` to make the tests work like before.
```         Room
          .inMemoryDatabaseBuilder(context, db)
          .allowMainThreadQueries()
          .setQueryExecutor(executor)
          .setTransactionExecutor(executor)```
Additional note: I also tried using `StandardTestDispatcher().asExecutor()` which I believe is the replacement for the deprecated `TestCoroutineDispatcher()`  but that did not work as well.

cc: <@U0B98KWF4> <@U2245FK37>

Hi <@U0B98KWF4>, the tests on my project was working on Room v2.3. Changing only the dispatcher executor on my tests to <http://Dispatchers.IO|Dispatchers.IO> makes it pass on v2.4.

In this setup, the executor was set to  `Executors.newSingleThreadExecutor()`  in  Room 2.3 and the tests involving PgingSource `load` was working fine. In Room 2.4, these tests suddenly failed, the `load` function wasn't returning and causing the tests to take too long. Changing it `<http://Dispatchers.IO|Dispatchers.IO>.asExecutor()`  made it pass again.
```         Room
          .inMemoryDatabaseBuilder(context, db)
          .allowMainThreadQueries()
          .setQueryExecutor(executor)
          .setTransactionExecutor(executor)```

If you pass the same executor to both read and write executors, it doesn't work with coroutines due to a conflict with android SQLite transactions (they are thread bound).

As for that test, it probably passed because it was using the dispatchers io, I assume that's not what you would want especially if you were passing a special executor to room

Thank you <@U0B98KWF4>.  Switching to different executors between the read and write fixed the tests. Using `newSingleThreadExecutor` (write) and `TestCoroutineDispatcher` (read) as executor made it work for me.