### Question:
InvestorService { public Stock fetchSingleStockByInvestorIdAndStockSymbol(String investorId, String symbol) { Investor investor = fetchInvestorById(investorId); return investor.getStocks().stream().filter(stock -> symbol.equalsIgnoreCase(stock.getSymbol())).findAny() .orElse(null); }  List<Investor> fetchAllInvestors(); Investor fetchInvestorById(String investorId); List<Stock> fetchStocksByInvestorId(String investorId, int offset, int limit); Stock fetchSingleStockByInvestorIdAndStockSymbol(String investorId, String symbol); String welcomePage();  }### Answer:
@Test public void testFetchSingleStockByInvestorIdAndStockSymbol() { String investorId = "Invr_1"; String expectedSymbol = "EXA"; String actualSymbol = (getInvestorServiceForTest() .fetchSingleStockByInvestorIdAndStockSymbol(investorId, expectedSymbol).getSymbol()); assertEquals(expectedSymbol, actualSymbol); }