Verifying data being posted from frisby test in Node backend

I'd like to check if the data is actually posting to my backend successfully via my Frisby test. I can see in the console the URL calls successfully and the response code is 201. However, when I print req.body, it's empty.

Jasmine/Frisby Tests

describe("POST /createSecret", function() {

  it('returns a status code of 201', function(done) {

    //Send a POST req. to create secret data
    frisby.create('GET JSON data from an endpoint')
      .post('http://localhost:3000/createSecret', {

            'secret_name'       : barbicanRequestData.secret_name,
            'expiration'        : barbicanRequestData.expiration,
            'algorithm'         : barbicanRequestData.algorithm,
            'bit_length'        : barbicanRequestData.bit_length,
            'mode'              : barbicanRequestData.mode,
            'payload'           : barbicanRequestData.payload,
            'content_type'      : barbicanRequestData.content_type,
            'content_encoding'  : barbicanRequestData.content_encoding,
            'secret_type'       : barbicanRequestData.secret_type
      })
      .expectStatus(201)
      .expectHeader('Content-Type', 'application/json; charset=utf-8')
      .expectJSON({ 'secret_ref': 'Secret was successfully created!' })
    .toss();
    done();
  });
});

Backend

  else if (req.method == "POST") {

    console.log("Request is POST");

    console.log(res.body);

    //Test a POST response for creating a secret using the Barbican API
    res.status(201).send({
      'secret_ref': "Secret was successfully created!",
      'Content-Type': 'application/json; charset=utf-8'
    });
  }