REST helper config: `onResponse` provided in config does not work

[apatelia]

I am using default REST helper for API testing, and I want to measure and assert the API's response time. For that I am trying following.

In my codecept.conf.ts:

  helpers: {
    REST: {
      endpoint: 'https://myServerUrl',

      onRequest: (request) => {
        console.log('onRequest');
        request.headers[ 'start-time' ] = new Date().getTime();
      },

      onResponse: (response) => {
        console.log('onResponse');
        const startTime = response.request.headers[ 'start-time' ];
        const endTime = new Date().getTime();
        const responseTime = endTime - startTime;
        response. Headers[ 'x-response-time' ] = responseTime;
      },
    },

    JSONResponse: {}
  }

and then in my custom helper:

    const response = this.helpers.JSONResponse.response;
    
    console.log(`Response time: ${response.headers[ 'x-response-time' ]} ms`);

I can see that onRequest from REST config works as expected but onResponse does not work.

My output:

onRequest
Response time: undefined ms