title: How can I write a test case for an interface?
body: <p>I need to get 100% code coverage for an interface class, how can I write a junit test case to test an interface.</p>
  
  <pre><code>public interface RetrieveOperation {
    public RetrieveClassOfServiceProfileResponse
        retrieve(String login, RetrieveClassOfServiceProfileRequest request)
        throws Exception;
  }
  </code></pre>