source: class CalculateNAVTest {
  
      @Test
      public void yahooFinanceIntegrationTest() {
  
target:         final CalculateNAV calculateNav = new CalculateNAV( YahooFinance::getPrice );
          BigDecimal oneGOOGShare = calculateNav.computeStockWorth( "GOOG", 1 );
          assertNotNull( oneGOOGShare );
          BigDecimal zero = new BigDecimal( 0 );
          assertTrue( oneGOOGShare.compareTo( zero ) >= 0 );
  
          // What if it changes between oneGOOGShare calc and now?
          BigDecimal expectedTenGOOGShares = oneGOOGShare.multiply( new BigDecimal( 10 ) );
          BigDecimal actualTenGOOGShares = calculateNav.computeStockWorth( "GOOG", 10 );
          assertEquals( expectedTenGOOGShares, actualTenGOOGShares );
      }
  
  }