@Override
 protected void testAggregation(Object expectedValue, Block block) {
   Page page =
       OperatorAssertion.appendSampleWeight(ImmutableList.of(new Page(block)), WEIGHT).get(0);
   assertApproximateAggregation(
       getFunction(), page.getChannelCount() - 1, getConfidence(), (Double) expectedValue, page);
 }
  private void testCorrectnessOfErrorFunction(List<Number> inputList) throws Exception {
    int inRange = 0;
    int numberOfRuns = 1000;
    double sampleRatio = 1 / (double) WEIGHT;
    double actual = getExpectedValue(inputList);
    Random rand = new Random(1);

    for (int i = 0; i < numberOfRuns; i++) {
      // Compute Sampled Value using sampledList (numberOfRuns times)
      ImmutableList.Builder<Number> sampledList = ImmutableList.builder();
      for (Number x : inputList) {
        if (rand.nextDouble() < sampleRatio) {
          sampledList.add(x);
        }
      }

      BlockBuilder builder = getType().createBlockBuilder(new BlockBuilderStatus());
      for (Number sample : sampledList.build()) {
        if (getType() == BIGINT) {
          BIGINT.writeLong(builder, sample.longValue());
        } else if (getType() == DOUBLE) {
          DOUBLE.writeDouble(builder, sample.doubleValue());
        } else {
          throw new AssertionError("Can only handle longs and doubles");
        }
      }
      Page page = new Page(builder.build());
      page = OperatorAssertion.appendSampleWeight(ImmutableList.of(page), WEIGHT).get(0);
      Accumulator accumulator =
          getFunction()
              .bind(
                  ImmutableList.of(0),
                  Optional.<Integer>absent(),
                  Optional.of(page.getChannelCount() - 1),
                  getConfidence())
              .createAccumulator();

      accumulator.addInput(page);
      Block result = accumulator.evaluateFinal();

      String approxValue =
          BlockAssertions.toValues(accumulator.getFinalType(), result).get(0).toString();
      double approx = Double.parseDouble(approxValue.split(" ")[0]);
      double error = Double.parseDouble(approxValue.split(" ")[2]);

      // Check if actual answer lies within [approxAnswer - error, approxAnswer + error]
      if (Math.abs(approx - actual) <= error) {
        inRange++;
      }
    }

    BinomialDistribution binomial = new BinomialDistribution(numberOfRuns, getConfidence());
    int lowerBound = binomial.inverseCumulativeProbability(0.01);
    int upperBound = binomial.inverseCumulativeProbability(0.99);
    assertTrue(
        lowerBound < inRange && inRange < upperBound,
        String.format(
            "%d out of %d passed. Expected [%d, %d]",
            inRange, numberOfRuns, lowerBound, upperBound));
  }