@Test
public void getMessageIfLotReceiptsAndNoDays() {

    when(storage.getReceiptsCountWithoutBackup()).thenReturn(RECEIPTS_LOT);
    when(storage.getLastManualBackupDate()).thenReturn(new Date(0));
    final TestObserver<Integer> testObserver = manager.needToShowBackupReminder().test();
    testObserver.awaitTerminalEvent();
    testObserver.assertComplete()
            .assertComplete()
            .assertNoErrors()
            .assertValue(days -> days == NO_PREVIOUS_BACKUPS);
}