return resp;
        });

        // For Trans2FindNext2 calls
        final int[] nextCall = { 0 };
        when(tree.send(any(Trans2FindNext2.class), any(Trans2FindFirst2Response.class))).thenAnswer((InvocationOnMock inv) -> {
            Trans2FindFirst2Response resp = inv.getArgument(1);
            int call = nextCall[0]++;
            String[] names = batches.get(call + 1);

    while (true) {
      long current = longs.get(i);
      double currentVal = longBitsToDouble(current);
      double nextVal = updaterFunction.applyAsDouble(currentVal);
      long next = doubleToRawLongBits(nextVal);
      if (longs.compareAndSet(i, current, next)) {
        return nextVal;
      }
    }
  }

  /**
   * Returns the String representation of the current values of array.
   *