@Test
public void yahooFinanceIntegrationTest() {

    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 );
}