prometheus-cpp/tests/histogram_test.cc

#include <limits>

#include "gmock/gmock.h"

#include "lib/histogram.h"

using namespace testing;
using namespace prometheus;

class HistogramTest : public Test {};

TEST_F(HistogramTest, initialize_with_zero) {
  Histogram histogram{{}};
  auto metric = histogram.Collect();
  ASSERT_TRUE(metric.has_histogram());
  auto h = metric.histogram();
  EXPECT_EQ(h.sample_count(), 0);
  EXPECT_EQ(h.sample_sum(), 0);
}

TEST_F(HistogramTest, sample_count) {
  Histogram histogram{{1}};
  histogram.Observe(0);
  histogram.Observe(200);
  auto metric = histogram.Collect();
  ASSERT_TRUE(metric.has_histogram());
  auto h = metric.histogram();
  EXPECT_EQ(h.sample_count(), 2);
}

TEST_F(HistogramTest, sample_sum) {
  Histogram histogram{{1}};
  histogram.Observe(0);
  histogram.Observe(1);
  histogram.Observe(101);
  auto metric = histogram.Collect();
  ASSERT_TRUE(metric.has_histogram());
  auto h = metric.histogram();
  EXPECT_EQ(h.sample_sum(), 102);
}

TEST_F(HistogramTest, bucket_size) {
  Histogram histogram{{1, 2}};
  auto metric = histogram.Collect();
  ASSERT_TRUE(metric.has_histogram());
  auto h = metric.histogram();
  EXPECT_EQ(h.bucket_size(), 3);
}

TEST_F(HistogramTest, bucket_count) {
  Histogram histogram{{1, 2}};
  histogram.Observe(0);
  histogram.Observe(0.5);
  histogram.Observe(1.5);
  histogram.Observe(1.5);
  histogram.Observe(3);
  auto metric = histogram.Collect();
  ASSERT_TRUE(metric.has_histogram());
  auto h = metric.histogram();
  ASSERT_EQ(h.bucket_size(), 3);
  auto firstBucket = h.bucket(0);
  EXPECT_EQ(firstBucket.cumulative_count(), 2);
  auto secondBucket = h.bucket(1);
  EXPECT_EQ(secondBucket.cumulative_count(), 2);
  auto thirdBucket = h.bucket(2);
  EXPECT_EQ(thirdBucket.cumulative_count(), 1);
}

TEST_F(HistogramTest, bucket_bounds) {
  Histogram histogram{{1, 2}};
  auto metric = histogram.Collect();
  ASSERT_TRUE(metric.has_histogram());
  auto h = metric.histogram();
  ASSERT_EQ(h.bucket_size(), 3);
  EXPECT_EQ(h.bucket(0).upper_bound(), 1);
  EXPECT_EQ(h.bucket(1).upper_bound(), 2);
  EXPECT_EQ(h.bucket(2).upper_bound(), std::numeric_limits<double>::infinity());
}