Removing (dest != prev) check from LastUnique algorithm.

base/algorithm/sorted_ranges_unittest.cc

+// Copyright 2017 The Chromium 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 "base/algorithm/sorted_ranges.h"
+
+#include <algorithm>
+#include <random>
+
+#include "base/containers/container_test_utils.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace base {
+
+namespace {
+
+template <typename T>
+void UniquePickLastTest(const std::vector<T>& in,
+                        const std::vector<T>& expected) {

[dyaroshev, 2017/04/08 17:03:12]

Unused

+  std::vector<T> copy;
+  UniqueCopyPickLast(in.begin(), in.end(), std::back_inserter(copy));
+  EXPECT_EQ(copy, expected);
+  auto in_place = in;
+  in_place.erase(UniquePickLast(in_place.begin(), in_place.end()),
+                 in_place.end());
+  EXPECT_EQ(in_place, expected);
+}
+
+}  // namespace
+
+TEST(Algorithm, UniqueCopyPickLastTest) {
+  // Behavior should be identical to std::unique when used when algorithm is
+  // called with strict Equality.
+  {
+    auto CheckUniqueInts = [](const std::vector<int>& in) {
+      std::vector<int> expected;
+      std::unique_copy(in.begin(), in.end(), std::back_inserter(expected));
+
+      std::vector<int> copy;
+      UniqueCopyPickLast(in.begin(), in.end(), std::back_inserter(copy));
+      EXPECT_EQ(expected, copy);
+
+      auto in_place = in;
+      in_place.erase(UniquePickLast(in_place.begin(), in_place.end()),
+                     in_place.end());
+      EXPECT_EQ(expected, in_place);
+    };
+
+    CheckUniqueInts({});
+    CheckUniqueInts({1});
+    CheckUniqueInts({1, 2});
+    CheckUniqueInts({1, 2, 3});
+    CheckUniqueInts({1, 1});
+    CheckUniqueInts({1, 2, 2, 1});
+    CheckUniqueInts({1, 1, 1});
+    CheckUniqueInts({1, 3, 1});
+    CheckUniqueInts({1, 1, 2});
+    CheckUniqueInts({1, 2, 2});
+    CheckUniqueInts({1, 2, 2, 3, 3, 3});
+    CheckUniqueInts({1, 1, 1, 2, 3, 4, 5, 5, 5});
+
+    // More random input.
+    std::mt19937 gen;
+    std::uniform_int_distribution<> dis(1, 10);
+    for (int i = 10; i < 100; ++i) {
+      std::vector<int> random_input(i);
+      std::generate(random_input.begin(), random_input.end(),
+                    [&] { return dis(gen); });
+      CheckUniqueInts(random_input);
+    }
+  }
+
+  // Check that algorithm works with move only types (compilation is enough).
+  {
+    int input_range[] = {1, 2, 2};
+    std::vector<MoveOnlyInt> move_only(std::begin(input_range),
+                                       std::end(input_range));
+    move_only.erase(UniquePickLast(move_only.begin(), move_only.end()),
+                    move_only.end());
+
+    EXPECT_EQ(2U, move_only.size());
+    EXPECT_EQ(MoveOnlyInt(1), move_only[0]);
+    EXPECT_EQ(MoveOnlyInt(2), move_only[1]);
+  }
+
+  // Keep last.
+  {
+    using IntPair = std::pair<int, int>;
+    auto CheckTakeLastDuplicate = [](std::vector<IntPair> in,
+                                     const std::vector<int>& expected_second) {
+      in.erase(UniquePickLast(in.begin(), in.end(),
+                              [](const IntPair& lhs, const IntPair& rhs) {
+                                return lhs.first == rhs.first;
+                              }),
+               in.end());
+
+      ASSERT_EQ(expected_second.size(), in.size());
+
+      for (size_t i = 0; i < in.size(); ++i)
+        EXPECT_EQ(expected_second[i], in[i].second) << "i= " << i;
+    };
+
+    CheckTakeLastDuplicate({{1, 0}, {1, 1}, {2, 0}}, {1, 0});
+    CheckTakeLastDuplicate({{1, 0}, {1, 1}, {1, 2}}, {2});
+    CheckTakeLastDuplicate({{1, 0}, {2, 0}, {2, 1}}, {0, 1});
+    CheckTakeLastDuplicate({{1, 0}, {1, 1}, {2, 0}, {2, 1}}, {1, 1});
+    CheckTakeLastDuplicate({{1, 0}, {2, 0}, {1, 0}, {1, 1}}, {0, 0, 1});
+  }
+}
+
+}  // namespace base