### Question:
OtpService { public String getAuthenticationFromDownloadToken(final String token) throws OtpAuthenticationException { return getAuthenticationFromToken(downloadTokenCache.asMap(), token); } OtpService();  OtpService(final int duration, final TimeUnit units); String generateDownloadToken(final OtpAuthenticationToken authenticationToken); String getAuthenticationFromDownloadToken(final String token); String generateUiExtensionToken(final OtpAuthenticationToken authenticationToken); String getAuthenticationFromUiExtensionToken(final String token);  }### Answer:
@Test(expected = OtpAuthenticationException.class) public void testGetNonExistentDownloadToken() throws Exception { otpService.getAuthenticationFromDownloadToken("Not a real download token"); }