Angular2 not sending HTTP GET

The code listed in (A) never sends its HTTP request when test() is called whereas the almost identical code in (B) does work. Any idea what the problem is? I know whether the request is sent by watching the server logs. Also, if I make the request in (A) manually by pasting it into the browser, I get the expected response. I'm stumped!

(A)

import { Constants } from '../toplevel/constants'

import { Injectable }     from '@angular/core';
import { Http, Response, Headers, RequestOptions } from '@angular/http';
import { Observable} from 'rxjs/Rx';

import 'rxjs/add/operator/map';
import 'rxjs/add/operator/catch';


@Injectable()
export class SigninService {

  constructor (private http: Http, private constants : Constants) {

  }

  getToken(username: string, password: string) : Observable<string>{

    var url = `${this.constants.apiRoot}/users/${username}?${password}`

    console.log(`Calling api server with url ${url}`)

    return this.http.get(url)
      .map((res:Response) => JSON.stringify(res.json()))
      .catch((error:any) => Observable.throw(error.json().error || 'Server error'));

  }

 test() {

   this.getToken('jc', 'yadayada')
 }
}

(B: excerpt)

getDocument(id: string) : Observable<Document>{
  return this.http.get(`${this.apiUrl}/documents/${id}`)
  .map((res:Response) => new Document(res.json()['document']))
  .catch((error:any) => Observable.throw(error.json().error || 'Server error'));

  }