@Test
public void getFilesInFolderErrorIsForwarded() throws Exception {

    final Exception exception = new Exception("test");
    when(driveDataStreams.getFilesInFolder(anyString())).thenReturn(Single.error(exception));
    final TestObserver<FileList> testObserver = driveStreamsManager.getFilesInFolder(anyString()).test();
    testObserver.assertNoValues();
    testObserver.assertNotComplete();
    testObserver.assertError(Exception.class);
    verify(driveErrorStream).onNext(Optional.of(criticalSyncError));
}