How to decode nock recorded response

How to ad-hoc decode/uncompress the output produced by the nock recorder so we can see the response as text? I guess we do not understand if the response is gzipped and/or encoded

The object works find when we load it into nock, and our tests are behaving as we expect. To see what the API produced, we are having to put logging statements in the implementation file.

We are recording and saving the JSON the responses:

nock.recorder.rec({output_objects: true, dont_print: true});
JSON.stringify(nock.recorder.play())

And our file looks like:

[
  {
    "scope": "https://some.api.com:443",
    "method": "POST",
    "path": "/auth?key=some_key",
    "body": {
      "logonId": "[e-mail]",
      "logonPassword": "secret"
    },
    "status": 400,
    "response": [
      "1f8b0800000000000000458cbd6ac34010067b3fc5c735691263bb741344ec42f827420a492916692d1d9cb461f71c218cdf3d97266e6786b92d00c7aaa205290d1c59cd6d71bb3fff8b376939a1cd6abd7ac003cf89b97a5f96757efecc8ef9aede9fb2fc586455f5f55eeedca33db119757f0f5704266334a2ca4d44ec19170941263f76f06657b62dd6cb2af919ec9357cc7255f0cb403e4014df643689b6687d3b3e450c149b1e534f1113a3a71f868cb8f8c04b7ca48b8fa08efcf8ea16f75fa1776d91ee000000"
    ],
    "headers": {
      "cache-control": "no-store, no-cache, must-revalidate",
      "content-encoding": "gzip",
      "content-type": "application/json",
      "transfer-encoding": "chunked",
      "connection": "Close"
    }
  }
]

Answer

The response from the http request is coming back as gzipped data, indicated by the content-encoding header. Nock is saving this data a hex encoded buffer string.

You can convert these cassettes into json with the following utility:

var zlib = require('zlib');
var fs = require('fs');
var argv = process.argv.slice(2);
var path = require('path');

var filename = path.resolve(argv[0]);
var file = fs.readFileSync(filename, { encoding: 'utf8' });
var cassettes = JSON.parse(file);

cassettes.forEach(function (cassette) {
  if (cassette.headers['content-encoding'] !== 'gzip') {
    return;
  }

  var response = new Buffer(cassette.response[0], 'hex');

  var contents = zlib.gunzipSync(response).toString('utf8');

  cassette.response = JSON.parse(contents);
  delete cassette.headers['content-encoding'];
});

fs.writeFileSync(filename, JSON.stringify(cassettes, null, 2), { encoding: 'utf8' });

Note, this will overwrite the original cassette with one that has converted all gzip requests into json. Also note that I’m not checking content type, so you’ll need to adapt this if you have responses that aren’t json.