title: Angular2 RC5 how to properly configure test module
body: <p>I'm updating my unit tests for Angular2 RC5. The <a href="https://github.com/angular/angular/blob/master/CHANGELOG.md#breaking-changes" rel="noreferrer">changelog</a> notes the following breaking change: </p>
  
  <blockquote>
    <p><code>addProviders</code> [is deprecated], use <code>TestBed.configureTestingModule</code> instead</p>
  </blockquote>
  
  <p>But this seems to take error only when attempting to include a service in a test. Where my unit test used to do the following: </p>
  
  <pre><code>beforeEach(() =&gt; addProviders([
      MyService,
      MockBackend,
      ... 
  ]));
  </code></pre>
  
  <p>it should now configure the test module:</p>
  
  <pre><code>TestBed.configureTestingModule({
      providers: [
          StoryService,
          MockBackend,
          ...
      ]
  });
  </code></pre>
  
  <p>But that now throws an error </p>
  
  <blockquote>
    <p>Service: MyService encountered a declaration exception FAILED</p>
    
    <p>Error: Cannot configure the test module when the test module has already been instantiated. Make sure you are not using <code>inject</code> before <code>TestBed.configureTestingModule</code>.</p>
  </blockquote>
  
  <p>I have checked that <code>inject</code> isn't been called before the <code>configureTestingModule</code>. This doesn't affect any other component/directive tests, they seem to pass just fine. How can I resolve this error for unit testing a service with RC5? I realize that I may have to wait until the the testing documentation are updated for RC5 but any insight into possible solutions would be much appreciated. </p>