title: Writing data to System.in
body: <p>In our application, we expect user input within a <code>Thread</code> as follows :</p>
  
  <pre><code>BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
  </code></pre>
  
  <p>I want to pass that part in my unit test so that I can resume the thread to execute the rest of the code. How can I write something into <code>System.in</code> from junit?</p>