code: /** 
   * Test that processing invalid less css produces exceptions
   */
  @Test public void shouldFailWhenInvalidLessCssIsProcessed() throws Exception {
    final ResourcePreProcessor processor=new RhinoLessCssProcessor(){
      @Override protected void onException(    final WroRuntimeException e){
        LOG.debug("[FAIL] Exception message is: {}",e.getMessage());
        throw e;
      }
    }
  ;
    final URL url=getClass().getResource("lesscss");
    final File testFolder=new File(url.getFile(),"invalid");
    WroTestUtils.forEachFileInFolder(testFolder,new Function<File,Void>(){
      @Override public Void apply(    final File input) throws Exception {
        try {
          processor.process(null,new FileReader(input),new StringWriter());
          Assert.fail("Expected to fail, but didn't");
        }
   catch (      final WroRuntimeException e) {
        }
        return null;
      }
    }
  );
  }
  