title: Jasmine: Mock parent class so I could isolate and test the son class
body: <p>I have the following scenario:</p>
  
  <pre><code>export class HttpClientService extends Http {...}    
  export class AppHttpClientService extends HttpClientService {...}
  </code></pre>
  
  <p>What I want is to override the <code>HttpClientService</code> to a mock class so I could make tests only on functions present on <code>AppHttpClientService</code>.</p>
  
  <p>How can I accomplish that?</p>