### Question:
InvestorService { public boolean deleteAStockFromTheInvestorPortfolio(String investorId, String stockTobeDeletedSymbol) { return deleteServiceFacade.deleteAStock(investorId, stockTobeDeletedSymbol); }  Stock addNewStockToTheInvestorPortfolio(String investorId, Stock newStock); boolean deleteAStockFromTheInvestorPortfolio(String investorId, String stockTobeDeletedSymbol); Stock updateAStockByInvestorIdAndStock(String investorId, Stock stockTobeUpdated); Stock updateAStockByInvestorIdAndStock(String investorId, String symbol, Stock stockTobeUpdated); List<Stock> bulkUpdateOfStocksByInvestorId(String investorId, List<Stock> stocksTobeUpdated);  }### Answer:
@Test public void testDeleteAStockToTheInvestorPortfolio() { Stock actualStock = new Stock("EXA", 150, 18.5); getInvestorServiceForTest().deleteAStockFromTheInvestorPortfolio("invr_1", actualStock.getSymbol()); Stock expectedStock = getInvestorServiceFetchOperationsForTest() .fetchSingleStockByInvestorIdAndStockSymbol("invr_1", "EXa"); assertNull(expectedStock); }