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setResponseCallback( callback )

Set the response callback to be called to determine if a response was expected/successful or not.

The result of this is that requests will be tagged with expected_response "true" or "false" and http_req_failed will be emitted with the reverse. This does include all redirects so if for a request only 200 is the expected response and there is 301 redirect before that, the redirect will be marked as failed as only status code 200 was marked as expected.


Due to implementation specifics:

  • Requests with authentication digest are always expected to first get 401 and then to get whatever was specified.
  • Requests with authentication ntlm will let a 401 status code on the first request as well as anything defined by expectedStatuses
callbackexpectedStatusesan object returned from expectedStatuses

Currently only the very special expectedStatuses objects are supported but in the future it is planned that a JavaScript callback will be supported as well. By default requests with status codes between 200 and 399 are considered "expected".

Setting the callback to null disables the tagging with expected_response and the emitting of http_req_failed.

It is recommended that if a per request responseCallback is used with Params it is actually defined once and used instead of creating it on each request.


import http from 'k6/http';
http.setResponseCallback(http.expectedStatuses({ min: 200, max: 300 }));
const only300Callback = http.expectedStatuses(300);
export default () => {
// this will use the default response callback and be marked as successful
// this will be marked as a failed request as it won't get the expected status code of 300
http.get('', { responseCallback: only300Callback });
// from here on for this VU only the 301 status code will be successful so on the next iteration of
// the VU the first request will be marked as failure