@Test
public void testSize() throws InterruptedException {

    final InternalThreadLocal<Integer> internalThreadLocal = new InternalThreadLocal<Integer>();
    internalThreadLocal.set(1);
    Assert.assertTrue("size method is wrong!", InternalThreadLocal.size() == 1);
    final InternalThreadLocal<String> internalThreadLocalString = new InternalThreadLocal<String>();
    internalThreadLocalString.set("value");
    Assert.assertTrue("size method is wrong!", InternalThreadLocal.size() == 2);
}