assertEquals(1, chain.updateCalls.size());
        assertEquals(user, chain.updateCalls.get(0));
        assertSame(user, chain.updateCalls.get(0));
    }

    // Test update with null user
    public void test_update_nullUser() {
        TestAuthenticationChain chain = new TestAuthenticationChain();
        chain.updateThrowsException = false;

        chain.update(null);

        assertEquals(1, chain.updateCalls.size());