### Question:
StockScreener { public Outcome screen(String ticker, Filter filter) { return filter.accept(ticker); }  Outcome screen(String ticker, Filter filter);  }### Answer:
@Test public void positive_screening() { StockScreener screener = new StockScreener(); assertEquals(Outcome.ok, screener.screen("GBX", new FixedPositiveFilter())); }
@Test public void negative_screening() { StockScreener screener = new StockScreener(); assertEquals(Outcome.ko, screener.screen("GBX", new FixedNegativeFilter())); }