chai http test with file upload

I am trying to create a unity test with file upload, but I get this message error:

TypeError: source.pause is not a function

My code looks like that:

const chai = require('chai'),
chaiHttp = require('chai-http'),
server   = require('../index'),
mongoose = require('mongoose'),
Product  = mongoose.model('Product'),
{readFileSync} = require("fs")

const product = new Product({
"name":"teste",
"product":"test",
"description": "a description test",
"quantity": 4,
"paid_value":1,
"sell_value":1,
"max_discount":0.5
})

it.only('it should create a product with image', (done) => {

  chai.request(server)
    .post('/product/create-product')
    .attach('image', readFileSync(__dirname+'/test.png'), 'avatar.png')
    .field('body',product)
    .end((err, res) => {
      res.should.have.status(200);
      res.body.should.be.a('object');
      res.body.should.have.property('success').eql(true);
      product.remove({ _id: product._id }, (err) => {})
      done();
    });

})

What Am I doing wrong? I am using restify.bodyparser for receiving these kind of request

server.use(restify.bodyParser({
   maxBodySize: 0,
   uploadDir: os.tmpdir(),
   multiples: true
}));