title: Exception using Transformer and PowerMockRunner
body: <p>I want to convert Document to String. I'm using the following method:</p>
  <pre><code>public static String toString(Document doc) {
      try {
          TransformerFactory tf = TransformerFactory.newInstance();
          Transformer transformer = tf.newTransformer();
          transformer.setOutputProperty(OutputKeys.OMIT_XML_DECLARATION, &quot;no&quot;);
  
          StringWriter sw = new StringWriter();
          transformer.transform(new DOMSource(doc), new StreamResult(sw));
          String writerAsString = sw.toString();
          return writerAsString;
      } catch (Exception ex) {
          throw new RuntimeException(&quot;Error converting to String&quot;, ex);
      }
  }
  </code></pre>
  <p>The code is working fine, but when I run tests and define @RunWith(PowerMockRunner.class) I get an error:</p>
  <pre><code>Caused by: com.sun.org.apache.xml.internal.serializer.utils.WrappedRuntimeException: Could not load the propery file 'output_xml.properties' for output method 'xml' (check CLASSPATH)
  </code></pre>
  <p>Can anyone help?</p>