No http response in angular HttpClient context using mocha

[nowrap]

Hello,
i am trying to build a mocha test for parts of an ionic 3 (angular 5) app.

I created an angular HttpClient with your XMLHttpRequest:

import { Injector } from '@angular/core';
import { HttpClient, HttpHandler, HttpXhrBackend, XhrFactory } from '@angular/common/http';
import { XMLHttpRequest } from 'xmlhttprequest-ts';

export class BrowserXhr implements XhrFactory {
    build(): any { return <any>(new XMLHttpRequest()); }
}

        const injector: Injector = Injector.create({
            providers: [
                { provide: HttpClient, deps: [HttpHandler] },
                { provide: HttpHandler, useValue: new HttpXhrBackend(new BrowserXhr()) },
            ],
        });
        const httpClient: HttpClient = injector.get(HttpClient);

Retriving local json files with a file:// url works.
Doing get or post requests are submitted and processed on the server side. But i am not getting the body. The result header is within. Instead i receive an object starting with "result: IncomingMessage {".

I tried using the webstorm debugger but couldn't get any clues. It uses first the node_modules/xmlhttprequest-ts/bundles/xmlhttprequest-ts.umd.js but switches to XMLHttpRequest.ts at line 442 "if (this.settings.async) {" ignoring my further breakpoints.

I guess it is somehow related to the responseHandler.

Regards
nowrap