how to test with SecurityMockMvcRequest for locked accounts?

My user implements the UserDetails interface and after 5 tries I lock its account.The login form works as expected

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How would you test with SecurityMockMvcRequest if user’s account is locked or not ?
The code below would seem reasonable


but it fails so I write


and this passes the test but I would need to see the server to return that the account is locked. Must I return a special error code ?