title: Sinon does not mock provided URL for GET with parameters
body: <p>I am trying to develop test for my services in Angular app and facing some issues with it.</p>
  
  <p>Here is the service code:</p>
  
  <pre><code>/**
   * Sends http request to get client states and territories available for specific vertical
   *
   * @param {number} vertical id of specific vertical. The following mapping is used:
   *    0 - Federal
   *    1 - State
   *    2 - Local
   *    3 - Education
   * @returns {Observable&lt;State[]&gt;} array of state objects with its display name and value as observable
   */
  getClientsStatesByVertical(vertical: VerticalEnum): Observable&lt;State[]&gt; {
    let params = new HttpParams();
    if (vertical != null) {
      params = params.append('vertical', String(vertical));
    }
    return this.http
      .get(`${CLIENT_API_ENDPOINT}/csr/states`, {params: params}) as   Observable&lt;State[]&gt;;
  }
  </code></pre>
  
  <p>Here is my test:</p>
  
  <pre><code>it('#getClientsStatesByVertical with vertical provided', (done) =&gt; {
    const expectation = [{label: 'Georgia', value: 'GA'}];
    server.respondWith('GET', `${CLIENT_API_ENDPOINT}/csr/states?vertical=${VerticalEnum.Federal}`);
    const o = service.getClientsStatesByVertical(VerticalEnum.Federal);
    o.subscribe(response =&gt; {
      expect(response).toEqual(expectation);
      done();
    });
    server.respond();
  });
  </code></pre>
  
  <p>I am getting the following error when I am running this test using karma:</p>
  
  <pre><code>HttpErrorResponse: Fake server request processing threw exception: Http failure response for http://localhost:19000/api/v1/clients/csr/states: 404 Not Found
  </code></pre>
  
  <p>Could you please point me to the issue, seems that I am missing smth simple, cause almost the same cases with shorter URLs are working perfectly</p>