internal/ceres/algorithm_test.cc

// Copyright 2017 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 "ceres/internal/algorithm.h"

#include <algorithm>
#include <list>
#include <vector>

#include "gmock/gmock.h"
#include "gtest/gtest.h"

namespace {

TEST(EqualTest, DefaultComparisonRandomAccess) {
  std::vector<int> v1{1, 2, 3};
  std::vector<int> v2 = v1;
  std::vector<int> v3 = {1, 2};
  std::vector<int> v4 = {1, 2, 4};

  EXPECT_TRUE(
      ceres::internal::equal(v1.begin(), v1.end(), v2.begin(), v2.end()));
  EXPECT_FALSE(
      ceres::internal::equal(v1.begin(), v1.end(), v3.begin(), v3.end()));
  EXPECT_FALSE(
      ceres::internal::equal(v1.begin(), v1.end(), v4.begin(), v4.end()));
}

TEST(EqualTest, DefaultComparison) {
  std::list<int> lst1{1, 2, 3};
  std::list<int> lst2 = lst1;
  std::list<int> lst3{1, 2};
  std::list<int> lst4{1, 2, 4};

  EXPECT_TRUE(ceres::internal::equal(
      lst1.begin(), lst1.end(), lst2.begin(), lst2.end()));
  EXPECT_FALSE(ceres::internal::equal(
      lst1.begin(), lst1.end(), lst3.begin(), lst3.end()));
  EXPECT_FALSE(ceres::internal::equal(
      lst1.begin(), lst1.end(), lst4.begin(), lst4.end()));
}

TEST(EqualTest, EmptyRange) {
  std::vector<int> v1{1, 2, 3};
  std::vector<int> empty1;
  std::vector<int> empty2;

  EXPECT_FALSE(ceres::internal::equal(
      v1.begin(), v1.end(), empty1.begin(), empty1.end()));
  EXPECT_FALSE(ceres::internal::equal(
      empty1.begin(), empty1.end(), v1.begin(), v1.end()));
  EXPECT_TRUE(ceres::internal::equal(
      empty1.begin(), empty1.end(), empty2.begin(), empty2.end()));
}

TEST(EqualTest, MixedIterTypes) {
  std::vector<int> v1{1, 2, 3};
  std::list<int> lst1{v1.begin(), v1.end()};
  std::list<int> lst2{1, 2, 4};
  std::list<int> lst3{1, 2};

  EXPECT_TRUE(
      ceres::internal::equal(v1.begin(), v1.end(), lst1.begin(), lst1.end()));
  EXPECT_FALSE(
      ceres::internal::equal(v1.begin(), v1.end(), lst2.begin(), lst2.end()));
  EXPECT_FALSE(
      ceres::internal::equal(v1.begin(), v1.end(), lst3.begin(), lst3.end()));
}

TEST(EqualTest, MixedValueTypes) {
  std::vector<int> v1{1, 2, 3};
  std::vector<char> v2{1, 2, 3};
  std::vector<char> v3{1, 2};
  std::vector<char> v4{1, 2, 4};

  EXPECT_TRUE(
      ceres::internal::equal(v1.begin(), v1.end(), v2.begin(), v2.end()));
  EXPECT_FALSE(
      ceres::internal::equal(v1.begin(), v1.end(), v3.begin(), v3.end()));
  EXPECT_FALSE(
      ceres::internal::equal(v1.begin(), v1.end(), v4.begin(), v4.end()));
}

TEST(EqualTest, WeirdIterators) {
  std::vector<bool> v1{true, false};
  std::vector<bool> v2 = v1;
  std::vector<bool> v3{true};
  std::vector<bool> v4{true, true, true};

  EXPECT_TRUE(
      ceres::internal::equal(v1.begin(), v1.end(), v2.begin(), v2.end()));
  EXPECT_FALSE(
      ceres::internal::equal(v1.begin(), v1.end(), v3.begin(), v3.end()));
  EXPECT_FALSE(
      ceres::internal::equal(v1.begin(), v1.end(), v4.begin(), v4.end()));
}

TEST(EqualTest, CustomComparison) {
  int n[] = {1, 2, 3, 4};
  std::vector<int*> v1{&n[0], &n[1], &n[2]};
  std::vector<int*> v2 = v1;
  std::vector<int*> v3{&n[0], &n[1], &n[3]};
  std::vector<int*> v4{&n[0], &n[1]};

  auto eq = [](int* a, int* b) { return *a == *b; };

  EXPECT_TRUE(
      ceres::internal::equal(v1.begin(), v1.end(), v2.begin(), v2.end(), eq));
  EXPECT_FALSE(
      ceres::internal::equal(v1.begin(), v1.end(), v3.begin(), v3.end(), eq));
  EXPECT_FALSE(
      ceres::internal::equal(v1.begin(), v1.end(), v4.begin(), v4.end(), eq));
}

TEST(EqualTest, MoveOnlyPredicate) {
  std::vector<int> v1{1, 2, 3};
  std::vector<int> v2{4, 5, 6};

  // move-only equality predicate
  struct Eq {
    Eq() = default;
    Eq(Eq&&) = default;
    Eq(const Eq&) = delete;
    Eq& operator=(const Eq&) = delete;
    bool operator()(const int a, const int b) const { return a == b; }
  };

  EXPECT_TRUE(
      ceres::internal::equal(v1.begin(), v1.end(), v1.begin(), v1.end(), Eq()));
  EXPECT_FALSE(
      ceres::internal::equal(v1.begin(), v1.end(), v2.begin(), v2.end(), Eq()));
}

struct CountingTrivialPred {
  int* count;
  bool operator()(int, int) const {
    ++*count;
    return true;
  }
};

TEST(EqualTest, RandomAccessComplexity) {
  std::vector<int> v1{1, 1, 3};
  std::vector<int> v2 = v1;
  std::vector<int> v3{1, 2};

  do {
    int count = 0;
    ceres::internal::equal(v1.begin(),
                           v1.end(),
                           v2.begin(),
                           v2.end(),
                           CountingTrivialPred{&count});
    EXPECT_LE(count, 3);
  } while (std::next_permutation(v2.begin(), v2.end()));

  int count = 0;
  ceres::internal::equal(
      v1.begin(), v1.end(), v3.begin(), v3.end(), CountingTrivialPred{&count});
  EXPECT_EQ(count, 0);
}
}  // namespace