assertNull(result);
        assertEquals(1, chain.loadCalls.size());
        assertEquals(inputUser, chain.loadCalls.get(0));
    }

    // Test load with multiple calls
    public void test_load_multipleCalls() {
        TestAuthenticationChain chain = new TestAuthenticationChain();
        User user1 = createTestUser("user1", "User One");
        User user2 = createTestUser("user2", "User Two");