prometheus-cpp/core/tests/summary_test.cc

#include <gmock/gmock.h>

#include <prometheus/summary.h>

#include <cmath>
#include <thread>

using namespace testing;
using namespace prometheus;

class SummaryTest : public Test {};

TEST_F(SummaryTest, initialize_with_zero) {
  Summary summary{Summary::Quantiles{}};
  auto metric = summary.Collect();
  auto s = metric.summary;
  EXPECT_EQ(s.sample_count, 0);
  EXPECT_EQ(s.sample_sum, 0);
}

TEST_F(SummaryTest, sample_count) {
  Summary summary{Summary::Quantiles{{0.5, 0.05}}};
  summary.Observe(0);
  summary.Observe(200);
  auto metric = summary.Collect();
  auto s = metric.summary;
  EXPECT_EQ(s.sample_count, 2);
}

TEST_F(SummaryTest, sample_sum) {
  Summary summary{Summary::Quantiles{{0.5, 0.05}}};
  summary.Observe(0);
  summary.Observe(1);
  summary.Observe(101);
  auto metric = summary.Collect();
  auto s = metric.summary;
  EXPECT_EQ(s.sample_sum, 102);
}

TEST_F(SummaryTest, quantile_size) {
  Summary summary{Summary::Quantiles{{0.5, 0.05}, {0.90, 0.01}}};
  auto metric = summary.Collect();
  auto s = metric.summary;
  EXPECT_EQ(s.quantile.size(), 2);
}

TEST_F(SummaryTest, quantile_bounds) {
  Summary summary{Summary::Quantiles{{0.5, 0.05}, {0.90, 0.01}, {0.99, 0.001}}};
  auto metric = summary.Collect();
  auto s = metric.summary;
  ASSERT_EQ(s.quantile.size(), 3);
  EXPECT_DOUBLE_EQ(s.quantile.at(0).quantile, 0.5);
  EXPECT_DOUBLE_EQ(s.quantile.at(1).quantile, 0.9);
  EXPECT_DOUBLE_EQ(s.quantile.at(2).quantile, 0.99);
}

TEST_F(SummaryTest, quantile_values) {
  static const int SAMPLES = 1000000;

  Summary summary{Summary::Quantiles{{0.5, 0.05}, {0.9, 0.01}, {0.99, 0.001}}};
  for (int i = 1; i <= SAMPLES; ++i) summary.Observe(i);

  auto metric = summary.Collect();
  auto s = metric.summary;
  ASSERT_EQ(s.quantile.size(), 3);

  EXPECT_NEAR(s.quantile.at(0).value, 0.5 * SAMPLES, 0.05 * SAMPLES);
  EXPECT_NEAR(s.quantile.at(1).value, 0.9 * SAMPLES, 0.01 * SAMPLES);
  EXPECT_NEAR(s.quantile.at(2).value, 0.99 * SAMPLES, 0.001 * SAMPLES);
}

TEST_F(SummaryTest, max_age) {
  Summary summary{Summary::Quantiles{{0.99, 0.001}}, std::chrono::seconds(1), 2};
  summary.Observe(8.0);

  static const auto test_value = [&summary](double ref) {
    auto metric = summary.Collect();
    auto s = metric.summary;
    ASSERT_EQ(s.quantile.size(), 1);

    if (std::isnan(ref))
      EXPECT_TRUE(std::isnan(s.quantile.at(0).value));
    else
      EXPECT_DOUBLE_EQ(s.quantile.at(0).value, ref);
  };

  test_value(8.0);
  std::this_thread::sleep_for(std::chrono::milliseconds(600));
  test_value(8.0);
  std::this_thread::sleep_for(std::chrono::milliseconds(600));
  test_value(std::numeric_limits<double>::quiet_NaN());
}