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diff --git a/absl/debugging/internal/bounded_utf8_length_sequence_test.cc b/absl/debugging/internal/bounded_utf8_length_sequence_test.cc
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+++ b/absl/debugging/internal/bounded_utf8_length_sequence_test.cc
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+// Copyright 2024 The Abseil Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "absl/debugging/internal/bounded_utf8_length_sequence.h"
+
+#include <cstdint>
+
+#include "gtest/gtest.h"
+#include "absl/base/config.h"
+
+namespace absl {
+ABSL_NAMESPACE_BEGIN
+namespace debugging_internal {
+namespace {
+
+TEST(BoundedUtf8LengthSequenceTest, RemembersAValueOfOneCorrectly) {
+  BoundedUtf8LengthSequence<32> seq;
+  ASSERT_EQ(seq.InsertAndReturnSumOfPredecessors(0, 1), 0);
+  EXPECT_EQ(seq.InsertAndReturnSumOfPredecessors(1, 1), 1);
+}
+
+TEST(BoundedUtf8LengthSequenceTest, RemembersAValueOfTwoCorrectly) {
+  BoundedUtf8LengthSequence<32> seq;
+  ASSERT_EQ(seq.InsertAndReturnSumOfPredecessors(0, 2), 0);
+  EXPECT_EQ(seq.InsertAndReturnSumOfPredecessors(1, 1), 2);
+}
+
+TEST(BoundedUtf8LengthSequenceTest, RemembersAValueOfThreeCorrectly) {
+  BoundedUtf8LengthSequence<32> seq;
+  ASSERT_EQ(seq.InsertAndReturnSumOfPredecessors(0, 3), 0);
+  EXPECT_EQ(seq.InsertAndReturnSumOfPredecessors(1, 1), 3);
+}
+
+TEST(BoundedUtf8LengthSequenceTest, RemembersAValueOfFourCorrectly) {
+  BoundedUtf8LengthSequence<32> seq;
+  ASSERT_EQ(seq.InsertAndReturnSumOfPredecessors(0, 4), 0);
+  EXPECT_EQ(seq.InsertAndReturnSumOfPredecessors(1, 1), 4);
+}
+
+TEST(BoundedUtf8LengthSequenceTest, RemembersSeveralAppendedValues) {
+  BoundedUtf8LengthSequence<32> seq;
+  ASSERT_EQ(seq.InsertAndReturnSumOfPredecessors(0, 1), 0);
+  ASSERT_EQ(seq.InsertAndReturnSumOfPredecessors(1, 4), 1);
+  ASSERT_EQ(seq.InsertAndReturnSumOfPredecessors(2, 2), 5);
+  ASSERT_EQ(seq.InsertAndReturnSumOfPredecessors(3, 3), 7);
+  ASSERT_EQ(seq.InsertAndReturnSumOfPredecessors(4, 1), 10);
+}
+
+TEST(BoundedUtf8LengthSequenceTest, RemembersSeveralPrependedValues) {
+  BoundedUtf8LengthSequence<32> seq;
+  ASSERT_EQ(seq.InsertAndReturnSumOfPredecessors(0, 4), 0);
+  ASSERT_EQ(seq.InsertAndReturnSumOfPredecessors(0, 3), 0);
+  ASSERT_EQ(seq.InsertAndReturnSumOfPredecessors(0, 2), 0);
+  ASSERT_EQ(seq.InsertAndReturnSumOfPredecessors(0, 1), 0);
+  ASSERT_EQ(seq.InsertAndReturnSumOfPredecessors(4, 1), 10);
+  ASSERT_EQ(seq.InsertAndReturnSumOfPredecessors(3, 1), 6);
+  ASSERT_EQ(seq.InsertAndReturnSumOfPredecessors(2, 1), 3);
+  ASSERT_EQ(seq.InsertAndReturnSumOfPredecessors(1, 1), 1);
+}
+
+TEST(BoundedUtf8LengthSequenceTest, RepeatedInsertsShiftValuesOutTheRightEnd) {
+  BoundedUtf8LengthSequence<32> seq;
+  ASSERT_EQ(seq.InsertAndReturnSumOfPredecessors(0, 2), 0);
+  for (uint32_t i = 1; i < 31; ++i) {
+    ASSERT_EQ(seq.InsertAndReturnSumOfPredecessors(0, 1), 0)
+        << "while moving the 2 into position " << i;
+    ASSERT_EQ(seq.InsertAndReturnSumOfPredecessors(31, 1), 32)
+        << "after moving the 2 into position " << i;
+  }
+  ASSERT_EQ(seq.InsertAndReturnSumOfPredecessors(0, 1), 0)
+      << "while moving the 2 into position 31";
+  EXPECT_EQ(seq.InsertAndReturnSumOfPredecessors(31, 1), 31)
+      << "after moving the 2 into position 31";
+}
+
+TEST(BoundedUtf8LengthSequenceTest, InsertsIntoWord1LeaveWord0Untouched) {
+  BoundedUtf8LengthSequence<64> seq;
+  for (uint32_t i = 0; i < 32; ++i) {
+    ASSERT_EQ(seq.InsertAndReturnSumOfPredecessors(i, 2), 2 * i)
+        << "at index " << i;
+  }
+  EXPECT_EQ(seq.InsertAndReturnSumOfPredecessors(32, 1), 64);
+  EXPECT_EQ(seq.InsertAndReturnSumOfPredecessors(32, 1), 64);
+}
+
+TEST(BoundedUtf8LengthSequenceTest, InsertsIntoWord0ShiftValuesIntoWord1) {
+  BoundedUtf8LengthSequence<64> seq;
+  ASSERT_EQ(seq.InsertAndReturnSumOfPredecessors(29, 2), 29);
+  ASSERT_EQ(seq.InsertAndReturnSumOfPredecessors(30, 3), 31);
+  ASSERT_EQ(seq.InsertAndReturnSumOfPredecessors(31, 4), 34);
+
+  // Pushing two 1's on the front moves the 3 and 4 into the high word.
+  ASSERT_EQ(seq.InsertAndReturnSumOfPredecessors(0, 1), 0);
+  ASSERT_EQ(seq.InsertAndReturnSumOfPredecessors(0, 1), 0);
+  ASSERT_EQ(seq.InsertAndReturnSumOfPredecessors(34, 1), 31 + 2 + 3 + 4);
+  ASSERT_EQ(seq.InsertAndReturnSumOfPredecessors(32, 1), 31 + 2);
+}
+
+TEST(BoundedUtf8LengthSequenceTest, ValuesAreShiftedCorrectlyAmongThreeWords) {
+  BoundedUtf8LengthSequence<96> seq;
+  ASSERT_EQ(seq.InsertAndReturnSumOfPredecessors(31, 3), 31);
+  ASSERT_EQ(seq.InsertAndReturnSumOfPredecessors(63, 4), 62 + 3);
+
+  // This insertion moves both the 3 and the 4 up a word.
+  ASSERT_EQ(seq.InsertAndReturnSumOfPredecessors(0, 1), 0);
+  ASSERT_EQ(seq.InsertAndReturnSumOfPredecessors(65, 1), 63 + 3 + 4);
+  ASSERT_EQ(seq.InsertAndReturnSumOfPredecessors(64, 1), 63 + 3);
+  ASSERT_EQ(seq.InsertAndReturnSumOfPredecessors(33, 1), 32 + 3);
+  ASSERT_EQ(seq.InsertAndReturnSumOfPredecessors(32, 1), 32);
+}
+
+}  // namespace
+}  // namespace debugging_internal
+ABSL_NAMESPACE_END
+}  // namespace absl