HeaderValuesMap implements Map<String, String[]> { public Set<String> keySet() { return new KeySet(request); } HeaderValuesMap(EnumeratedValuesExtractor request); void clear(); boolean containsKey(Object key); boolean containsValue(Object value); Set<Map.Entry<String, String[]>> entrySet(); @Override boolean equals(Object o); String[] get(Object key); @Override int hashCode(); boolean isEmpty(); Set<String> keySet(); String[] put(String key, String[] value); void putAll(Map<? extends String, ? extends String[]> map); String[] remove(Object key); int size(); Collection<String[]> values();  }
@Test public void testKeySet() { replay(extractor); assertTrue(map.keySet() instanceof KeySet); verify(extractor); }