JAASAuthenticator auth = spy(new JAASAuthenticator());
        // Avoid real JAAS by stubbing getSubject
        doReturn(new Subject()).when(auth).getSubject();

        // Act
        CredentialsInternal result = auth.renew();

        // Assert interaction and return value
        assertSame(auth, result);
        verify(auth, times(1)).getSubject();
    }

    void getSmbSession_createAndReuse() {
        // Arrange: minimal credentials chain so SmbSessionImpl constructor succeeds
        CredentialsInternal creds = mock(CredentialsInternal.class);
        when(ctx.getCredentials()).thenReturn(creds);
        when(creds.unwrap(CredentialsInternal.class)).thenReturn(creds);
        when(creds.clone()).thenReturn(creds);

        assertEquals(0, transport.getNumSessions());

            return null;
        }
    }

    /**
     * {@inheritDoc}
     *
     * @see jcifs.smb.SmbRenewableCredentials#renew()
     */
    @Override
    public CredentialsInternal renew() {
        log.debug("Renewing credentials");
        this.cachedSubject = null;
        getSubject();
        return this;
    }

    /**
     * {@inheritDoc}
     *

    private final SmbTransportImpl transport;
    private long expiration;
    private String netbiosName = null;

    private CIFSContext transportContext;

    private CredentialsInternal credentials;
    private byte[] sessionKey;
    private boolean extendedSecurity;

    private final AtomicLong usageCount = new AtomicLong(1);

 * when the "guest" username is supplied. Use {@link AuthenticationType} instead.
 *
 * @author mbechler
 */
public class NtlmPasswordAuthenticator implements Principal, CredentialsInternal, Serializable, AutoCloseable {

    /**
     *
     */
    private static final long serialVersionUID = -4090263879887877186L;

        Mockito.when(mockContext.getCredentials()).thenReturn(mockCredentials);

        // Mock CredentialsInternal for session tests
        jcifs.smb.CredentialsInternal mockCredentialsInternal = Mockito.mock(jcifs.smb.CredentialsInternal.class);
        Mockito.when(mockCredentials.unwrap(jcifs.smb.CredentialsInternal.class)).thenReturn(mockCredentialsInternal);

     *            the lifetime in seconds
     */
    public void setLifeTime(int time) {
        this.contextLifetime = time;
    }

    /**
     * {@inheritDoc}
     *
     * @see jcifs.smb.CredentialsInternal#isAnonymous()
     */
    @Override
    public boolean isAnonymous() {
        return this.getSubject() == null && super.isAnonymous();
    }

    /**
     * {@inheritDoc}
     *