source: class StrategyLoaderTest {
  
      @Test
      void loading() {
  
target:         final InvestmentStrategy is = (availableLoans, portfolio, restrictions) -> Stream.empty();
          final StrategyService iss = new StrategyService() {
              @Override
              public Optional<InvestmentStrategy> toInvest(final String strategy) {
                  return Optional.of(is);
              }
  
              @Override
              public Optional<SellStrategy> toSell(final String strategy) {
                  return Optional.empty();
              }
  
              @Override
              public Optional<PurchaseStrategy> toPurchase(final String strategy) {
                  return Optional.empty();
              }
  
              @Override
              public Optional<ReservationStrategy> forReservations(final String strategy) {
                  return Optional.empty();
              }
          };
          assertThat(StrategyLoader.load("", Collections.singleton(iss), StrategyService::toInvest))
              .contains(is);
      }
  
  }