Getting Error: getaddrinfo ENOTFOUND using https

I have created this simple class:

import https from 'https';

class Request {

    constructor(opts) {
        this.hostname = opts.hostname;
    }

    init(method, path, data = {}) {
        const optsReq = {
            hostname: this.hostname,
            path: path,
            method: method
        };

        return new Promise((resolve, reject) => {
            const req = https.request(optsReq, (response) => resolve(response));
            req.on('error', (error) => {
                console.log(error);
                reject(error);
            });
            req.end(JSON.stringify(data));
        });
    }

    get(path) {
        return this.init('GET', path);
    }

    post(path, data) {
        return this.init('POST', path, data);
    }

    put(path) {
        return this.init('PUT', path);
    }

    delete(path) {
        return this.init('DELETE', path);
    }

    patch(path) {
        return this.init('PATCH', path);
    }
}

export default Request;

and then I'm trying to test it:

import chai, { expect } from 'chai';
import chaiAsPromised from 'chai-as-promised';
import sinon from 'sinon';

import Request from '../src/request';

chai.use(chaiAsPromised);

describe('Request', () => {

    const hostname = 'fake-server.com';
    let server;

    before(() => {
        server = sinon.fakeServer.create();
        server.respondWith(
            'GET',
            `https://${hostname}/api/entities`,
            [ 200, { 'Content-type': 'application/json' }, JSON.stringify({ entities: 1 })]
        );
    });

    it('Receive HTTP 200 status code from a GET request', () => {
        const opts = { hostname };
        const req = new Request(opts).get('/api/entities');
        return expect(req).to.eventually.have.property('entities');
    });

    after(() => {
        server.restore();
    });
});

unfortunately whatever hostname I use I always get the following error:

[Error: getaddrinfo ENOTFOUND fake-server.com fake-server.com:443]

Any idea?