const http = require('http');
const https = require('https');

const nock = require('nock');
nock('https://httpbin.org').persist()
  .post('/post').reply(200, (uri, reqBody) => {
    return {
      "hits": {
        "total": 0
      }
    }
  });

const fetch = (url, o) => new Promise((resolve, reject) => {
  let body = o && o.body;
  if (typeof body === 'object') {
    o.headers = { ...o.headers, 'content-type': o.headers && o.headers['content-type'] || 'application/json' };
    body = JSON.stringify(body);
  }
  const req = (/^https:/.test(o && o.protocol || url) ? https : http).request(url, o);
  req.once('error', reject);
  req.once('response', res => {
    const bufs = [];
    res.on('data', buf => bufs.push(buf));
    res.on('end', () => {
      const text = Buffer.concat(bufs);
      if (res.headers.location) return fetch(res.headers.location, o || url).then(resolve)
      resolve(/^application\/json/.test(res.headers['content-type']) ? JSON.parse(text) : text);
    });
    res.on('error', reject);
  });
  if (body && typeof body.pipe === 'function') return body.pipe(req);
  if (body) {
    req.write(body);
  }
  req.end();
});

(async () => {
  await fetch('https://httpbin.org/post', { method: 'POST', body: { wat: 1 } }).then(console.log, console.error);
})()