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diff --git a/src/mongo/util/integer_histogram_test.cpp b/src/mongo/util/integer_histogram_test.cpp
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+/**
+ *    Copyright (C) 2021-present MongoDB, Inc.
+ *
+ *    This program is free software: you can redistribute it and/or modify
+ *    it under the terms of the Server Side Public License, version 1,
+ *    as published by MongoDB, Inc.
+ *
+ *    This program is distributed in the hope that it will be useful,
+ *    but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *    Server Side Public License for more details.
+ *
+ *    You should have received a copy of the Server Side Public License
+ *    along with this program. If not, see
+ *    <http://www.mongodb.com/licensing/server-side-public-license>.
+ *
+ *    As a special exception, the copyright holders give permission to link the
+ *    code of portions of this program with the OpenSSL library under certain
+ *    conditions as described in each individual source file and distribute
+ *    linked combinations including the program with the OpenSSL library. You
+ *    must comply with the Server Side Public License in all respects for
+ *    all of the code used other than as permitted herein. If you modify file(s)
+ *    with this exception, you may extend this exception to your version of the
+ *    file(s), but you are not obligated to do so. If you do not wish to do so,
+ *    delete this exception statement from your version. If you delete this
+ *    exception statement from all source files in the program, then also delete
+ *    it in the license file.
+ */
+
+#include "mongo/platform/basic.h"
+#include "mongo/unittest/death_test.h"
+#include "mongo/unittest/unittest.h"
+#include "mongo/util/integer_histogram.h"
+
+namespace mongo {
+
+namespace {
+
+TEST(IntegerHistogram, EnsureCountsIncrementedAndStored) {
+    std::array<int64_t, 4> lowerBounds{0, 5, 8, 12};
+    IntegerHistogram<4> hist("testKey", lowerBounds);
+    int64_t sum = 0;
+    int64_t numInserts = 15;
+    for (int64_t i = 0; i < numInserts; i++) {
+        hist.increment(i);
+        sum += i;
+    }
+
+    auto out = [&] {
+        BSONObjBuilder builder;
+        hist.append(builder, true);
+        return builder.obj();
+    }();
+
+    auto buckets = out["testKey"];
+    ASSERT_EQUALS(buckets["0 - 5"]["count"].Long(), 5);
+    ASSERT_EQUALS(buckets["5 - 8"]["count"].Long(), 3);
+    ASSERT_EQUALS(buckets["8 - 12"]["count"].Long(), 4);
+    ASSERT_EQUALS(buckets["12 - inf"]["count"].Long(), 3);
+    ASSERT_EQUALS(buckets["ops"].Long(), numInserts);
+    ASSERT_EQUALS(buckets["sum"].Long(), sum);
+    ASSERT_EQUALS(buckets["mean"].Double(), static_cast<double>(sum) / numInserts);
+}
+
+TEST(IntegerHistogram, EnsureCountsIncrementedInSmallestBucket) {
+    std::array<int64_t, 3> lowerBounds{5, 8, 12};
+    IntegerHistogram<3> hist("testKey2", lowerBounds);
+    int64_t sum = 0;
+    int64_t numInserts = 5;
+    for (int64_t i = 0; i < numInserts; i++) {
+        hist.increment(i);
+        sum += i;
+    }
+
+    auto out = [&] {
+        BSONObjBuilder builder;
+        hist.append(builder, true);
+        return builder.obj();
+    }();
+
+    auto buckets = out["testKey2"];
+    ASSERT_EQUALS(buckets["-inf - 5"]["count"].Long(), 5);
+    ASSERT_EQUALS(buckets["ops"].Long(), numInserts);
+    ASSERT_EQUALS(buckets["sum"].Long(), sum);
+    ASSERT_EQUALS(buckets["mean"].Double(), static_cast<double>(sum) / numInserts);
+}
+
+TEST(IntegerHistogram, EnsureCountsCorrectlyIncrementedAtBoundary) {
+    std::array<int64_t, 3> lowerBounds{5, 8, 12};
+    IntegerHistogram<3> hist("testKey3", lowerBounds);
+    int64_t sum = 0;
+    int64_t numInserts = 3;
+    for (auto& boundary : lowerBounds) {
+        hist.increment(boundary);
+        sum += boundary;
+    }
+
+    auto out = [&] {
+        BSONObjBuilder builder;
+        hist.append(builder, true);
+        return builder.obj();
+    }();
+
+    auto buckets = out["testKey3"];
+    ASSERT_EQUALS(buckets["5 - 8"]["count"].Long(), 1);
+    ASSERT_EQUALS(buckets["8 - 12"]["count"].Long(), 1);
+    ASSERT_EQUALS(buckets["12 - inf"]["count"].Long(), 1);
+    ASSERT_EQUALS(buckets["ops"].Long(), numInserts);
+    ASSERT_EQUALS(buckets["sum"].Long(), sum);
+    ASSERT_EQUALS(buckets["mean"].Double(), static_cast<double>(sum) / numInserts);
+}
+
+TEST(IntegerHistogram, EnsureNegativeCountsIncrementBucketsCorrectly) {
+    std::array<int64_t, 3> lowerBounds{-12, -8, 5};
+    IntegerHistogram<3> hist("testKey4", lowerBounds);
+    int64_t sum = 0;
+    int64_t numInserts = 25;
+    for (int64_t i = -15; i < 10; i++) {
+        hist.increment(i);
+        sum += i;
+    }
+
+    auto out = [&] {
+        BSONObjBuilder builder;
+        hist.append(builder, true);
+        return builder.obj();
+    }();
+
+    auto buckets = out["testKey4"];
+    ASSERT_EQUALS(buckets["-inf - -12"]["count"].Long(), 3);
+    ASSERT_EQUALS(buckets["-12 - -8"]["count"].Long(), 4);
+    ASSERT_EQUALS(buckets["-8 - 5"]["count"].Long(), 13);
+    ASSERT_EQUALS(buckets["5 - inf"]["count"].Long(), 5);
+    ASSERT_EQUALS(buckets["ops"].Long(), numInserts);
+    ASSERT_EQUALS(buckets["sum"].Long(), sum);
+    ASSERT_EQUALS(buckets["mean"].Double(), static_cast<double>(sum) / numInserts);
+}
+
+TEST(IntegerHistogram, SkipsEmptyBuckets) {
+    std::array<int64_t, 2> lowerBounds{0, 5};
+    IntegerHistogram<2> hist("testKey6", lowerBounds);
+    hist.increment(6);
+
+    auto out = [&] {
+        BSONObjBuilder builder;
+        hist.append(builder, true);
+        return builder.obj();
+    }();
+
+    auto buckets = out["testKey6"];
+    ASSERT_THROWS(buckets["0 - 5"]["count"].Long(), DBException);
+    ASSERT_EQ(buckets["5 - inf"]["count"].Long(), 1);
+}
+
+DEATH_TEST(IntegerHistogram,
+           FailIfFirstLowerBoundIsMin,
+           "Lower bounds must be strictly monotonically increasing") {
+    std::array<int64_t, 2> lowerBounds{std::numeric_limits<int64_t>::min(), 5};
+    IntegerHistogram<2> hist("testKey5", lowerBounds);
+}
+
+DEATH_TEST(IntegerHistogram,
+           FailsWhenLowerBoundNotMonotonic,
+           "Lower bounds must be strictly monotonically increasing") {
+    std::array<int64_t, 2> lowerBounds{5, 0};
+    IntegerHistogram<2>("testKey7", lowerBounds);
+}
+}  // namespace
+}  // namespace mongo