@Test
public void testTwoAccessTokensForSameUser() {

    ByteBuffer username = getAcceptableUsername();
    ByteBuffer password = getSecurePassword();
    service.create(username, password, Role.ADMIN);
    AccessToken token1 = service.tokens.issue(username);
    AccessToken token2 = service.tokens.issue(username);
    Assert.assertNotEquals(token1, token2);
    Assert.assertTrue(service.tokens.isValid(token1));
    Assert.assertTrue(service.tokens.isValid(token2));
}