### Question:
HashCache implements Cache { @Override public String get(String key) throws CacheException { try { return store.get(key); } catch (Exception e) { throw new CacheException("Cache error on get!", e); } } HashCache(); @Override String get(String key); @Override void put(String key, String value);  }### Answer:
@Test(expected = CacheException.class) public void gettRaisesCacheExceptionForNull() throws Exception { cache.get(null); }
@Test public void getReturnsNullWhenNotSet() throws Exception { assertNull(cache.get("key")); }