@Test
public void deleteErrorIsForwarded() throws Exception {

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