@Test
public void testInvalidate() {

    subject.put(FIRST_TEST_KEY, CACHE_ACTION);
    String value1 = subject.get(FIRST_TEST_KEY);
    // invalidate item
    subject.invalidate(FIRST_TEST_KEY);
    String value2 = subject.get(FIRST_TEST_KEY);
    assertNotEquals(value1, value2);
    // invalidate all
    subject.invalidateAll();
    String value3 = subject.get(FIRST_TEST_KEY);
    assertNotEquals(value2, value3);
}