@Test
void testSendChallengeDuringNegotiate() {

    final String myProtocol = "myProtocol";
    this.out = new byte[1];
    this.out[0] = -1;
    this.negAuthFilter.sendChallengeDuringNegotiate(myProtocol, this.response, this.out);
    Assertions.assertEquals(String.join(" ", myProtocol, Base64.getEncoder().encodeToString(this.out)),
            this.response.headers.get("WWW-Authenticate"));
    Assertions.assertEquals("keep-alive", this.response.headers.get("Connection"));
    Assertions.assertEquals(HttpServletResponse.SC_UNAUTHORIZED, this.response.sc);
    Assertions.assertEquals(0, this.response.errorCode);
    Assertions.assertFalse(this.response.isFlushed);
}