@Test
public void testGet() {

    String key = "A";
    GuavaCache<String, Integer> instance = new GuavaCache<>(100, Cache.EXPIRE_POLICY.AFTER_WRITE, 10000);
    instance.put(key, 1);
    Optional<Integer> result = instance.get(key);
    assertTrue(result.isPresent());
    assertEquals(Integer.valueOf(1), result.get());
}