src/algorithms/privacy/rmse_test.cc

// Copyright 2024 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "src/algorithms/privacy/rmse.h"

#include <gmock/gmock.h>
#include <gtest/gtest.h>

#include "src/algorithms/privacy/numeric_encoding.h"

using ::testing::DoubleEq;

namespace cobalt {

TEST(RmseTest, Unary) {
  double lambda = 9.0;

  EXPECT_THAT(PoissonUnaryRmse(lambda), DoubleEq(3.0));
}

namespace {

double PoissonSumRmseSlow(double lambda, double min_value, double max_value,
                          uint64_t num_index_points) {
  double expected_mse = 0;

  for (uint64_t i = 0; i < num_index_points; i++) {
    double xi = cobalt::DoubleFromIndex(i, min_value, max_value, num_index_points);
    expected_mse += lambda * xi * xi;
  }
  return std::sqrt(expected_mse);
}

}  // namespace

TEST(RmseTest, PoissonSumRmseSizeOneIntervals) {
  double lambda = 17.82;
  double min_value = 0;
  double max_value = 10;
  uint64_t num_index_points = 11;

  double expected_rmse = PoissonSumRmseSlow(lambda, min_value, max_value, num_index_points);

  EXPECT_THAT(expected_rmse,
              DoubleEq(PoissonSumRmse(lambda, min_value, max_value, num_index_points)));
}

TEST(RmseTest, PoissonSumRmseSizeLargerIntervals) {
  double lambda = 17.82;
  double min_value = 0;
  double max_value = 25;
  uint64_t num_index_points = 11;

  double expected_rmse = PoissonSumRmseSlow(lambda, min_value, max_value, num_index_points);

  EXPECT_THAT(expected_rmse,
              DoubleEq(PoissonSumRmse(lambda, min_value, max_value, num_index_points)));
}

TEST(RmseTest, PoissonSumRmseSizeNonZeroMin) {
  double lambda = 17.82;
  double min_value = 22;
  double max_value = 51;
  uint64_t num_index_points = 11;

  double expected_rmse = PoissonSumRmseSlow(lambda, min_value, max_value, num_index_points);

  EXPECT_THAT(expected_rmse,
              DoubleEq(PoissonSumRmse(lambda, min_value, max_value, num_index_points)));
}

}  // namespace cobalt