/** attempts to access tokenCache as from client */
    @Override
    public void map(IntWritable key, IntWritable value, Context context)
        throws IOException, InterruptedException {
      // get token storage and a key
      Credentials ts = context.getCredentials();
      byte[] key1 = ts.getSecretKey(new Text("alias1"));
      Collection<Token<? extends TokenIdentifier>> dts = ts.getAllTokens();
      int dts_size = 0;
      if (dts != null) dts_size = dts.size();

      if (dts_size != 2) { // one job token and one delegation token
        throw new RuntimeException("tokens are not available"); // fail the test
      }

      if (key1 == null || ts == null || ts.numberOfSecretKeys() != NUM_OF_KEYS) {
        throw new RuntimeException("secret keys are not available"); // fail the test
      }
      super.map(key, value, context);
    }