assertTrue(ex.getMessage().contains("ExtendedGSSContext is not implemented"));
    }

    @Test
    @DisplayName("initSecContext returns token and verifies interaction")
    void initSecContext_success() throws Exception {
        byte[] in = new byte[] { 10, 11 };
        byte[] out = new byte[] { 12, 13, 14 };
        when(gssContext.initSecContext(eq(in), eq(0), eq(in.length))).thenReturn(out);