cpp-useful-iterators/test/indexed_iterator_test.cxx

#include "iterator/indexed_iterator.h"

#include <map>
#include <vector>

#include "iterator/end_aware_iterator.h"

#include "ranges.h"
#include "xcode_gtest_helper.h"

using iterator::end_aware_iterator;
using iterator::indexed_iterator;

using testing::Ge;
using testing::Gt;
using testing::Le;
using testing::Lt;
using testing::Ne;

// TODO: This ought to be implemented as a compiles-test
TEST(IndexedIteratorTest, CanCastCompatibleIterators) {
  std::vector<int> v{1, 2, 3, 4, 5};
  indexed_iterator eai(v.begin());
  indexed_iterator<std::vector<int>::const_iterator>{eai};
}

TEST(IndexedIteratorTest, CanLieAboutIndex) {
  std::vector<int> vec{5, 3, 2, 8, 9, 11, 2, 4};
  indexed_iterator it(vec.begin(), 3);
  EXPECT_THAT(it->first, 3);
}

TEST(IndexedIteratorTest, FakeIndexDoesntEffectEqualityCheck) {
  std::vector<int> vec{5, 3, 2, 8, 9, 11, 2, 4};
  EXPECT_THAT(indexed_iterator(vec.begin()), indexed_iterator(vec.begin(), 3));
  EXPECT_THAT(indexed_iterator(vec.begin()) + 3,
              Ne(indexed_iterator(vec.begin(), 3)));
}

TEST(IndexedIteratorTest, DoesNotTrackByIndex) {
  std::vector<int> vec{5, 3, 2, 8, 9, 11, 2, 4};
  indexed_iterator end(vec.end());
  EXPECT_THAT(decltype(end){}, Ne(end));
}

TEST(IndexedIteratorTest, IteratorPropagatesAtEnd) {
  std::vector<int> vec{5, 3, 2, 8, 9, 11, 2, 4};
  indexed_iterator end(end_aware_iterator(vec.end(), vec.end()));

  EXPECT_EQ(end, iterator::sentinel);
}

TEST(IndexedIteratorTest, CanCompareIteratorOrder) {
  std::vector<int> vec{5, 3, 2, 8, 9, 11, 2, 4};
  indexed_iterator const begin(vec.begin());
  indexed_iterator const it = begin + 3;

  EXPECT_THAT(begin, Lt(it));
  EXPECT_THAT(begin, Le(it));
  EXPECT_THAT(it, Le(it));
  EXPECT_THAT(it, Gt(begin));
  EXPECT_THAT(it, Ge(begin));
  EXPECT_THAT(it, Ge(it));
}

TEST(IndexedIteratorTest, PreIncrementAdvancesIterator) {
  std::vector<int> vec{5, 3, 2, 8, 9, 11, 2, 4};
  indexed_iterator it(vec.begin() + 1);
  EXPECT_THAT(it->second, 3);
  EXPECT_THAT((++it)->second, 2);
  EXPECT_THAT(it->second, 2);
}

TEST(IndexedIteratorTest, PostIncrementReturnsCopyOfPrev) {
  std::vector<int> vec{5, 3, 2, 8, 9, 11, 2, 4};
  indexed_iterator it(vec.begin() + 1);
  EXPECT_THAT(it->second, 3);
  EXPECT_THAT((it++)->second, 3);
  EXPECT_THAT(it->second, 2);
}

TEST(IndexedIteratorTest, PreDecrementAdvancesIterator) {
  std::vector<int> vec{5, 3, 2, 8, 9, 11, 2, 4};
  indexed_iterator it(vec.begin() + 1);
  EXPECT_THAT(it->second, 3);
  EXPECT_THAT((--it)->second, 5);
  EXPECT_THAT(it->second, 5);
}

TEST(IndexedIteratorTest, PostDecrementReturnsCopyOfPrev) {
  std::vector<int> vec{5, 3, 2, 8, 9, 11, 2, 4};
  indexed_iterator it(vec.begin() + 1);
  EXPECT_THAT(it->second, 3);
  EXPECT_THAT((it--)->second, 3);
  EXPECT_THAT(it->second, 5);
}

TEST(IndexedIteratorTest, CanWalkNStepsForward) {
  std::vector<int> vec{5, 3, 2, 8, 9, 11, 2, 4};
  indexed_iterator const begin(vec.begin());
  indexed_iterator it = begin;
  it += 4;
  EXPECT_THAT(ranges::distance(begin, it), 4);
}

TEST(IndexedIteratorTest, CanWalkNStepsBackwards) {
  std::vector<int> vec{5, 3, 2, 8, 9, 11, 2, 4};
  indexed_iterator const end(vec.end());
  indexed_iterator it = end;
  it -= 4;
  EXPECT_THAT(ranges::distance(it, end), 4);
}

TEST(IndexedIteratorTest, RandomAccessIsPassthrough) {
  std::vector<int> vec{5, 3, 2, 8, 9, 11, 2, 4};
  EXPECT_THAT(indexed_iterator(vec.begin()) + 4,
              indexed_iterator(vec.begin() + 4));
  EXPECT_THAT(indexed_iterator(vec.end()) - 4, indexed_iterator(vec.end() - 4));
}

TEST(IndexedIteratorTest, TreatsVectorIteratorAsPairIdxValue) {
  std::vector<int> vec{5, 3, 2, 8, 9, 11, 2, 4};
  std::vector<std::pair<int, int>> const expected{
      {0, 5}, {1, 3}, {2, 2}, {3, 8}, {4, 9}, {5, 11}, {6, 2}, {7, 4}};

  std::vector<std::pair<int, int>> const result(indexed_iterator(vec.begin()),
                                                indexed_iterator(vec.end()));
  EXPECT_THAT(result, expected);
}

TEST(IndexedIteratorTest, TreatsVectorIteratorAsMapIdxToValue) {
  std::vector<int> vec{5, 3, 2, 8, 9, 11, 2, 4};
  std::map<int, int> const expected{{0, 5}, {1, 3},  {2, 2}, {3, 8},
                                    {4, 9}, {5, 11}, {6, 2}, {7, 4}};

  std::map<int, int> const result(indexed_iterator(vec.begin()),
                                  indexed_iterator(vec.end()));
  EXPECT_THAT(result, expected);
}

TEST(IndexedIteratorTest, CanMutatePointedToData) {
  std::vector<int> vec{5, 3, 2, 8, 9, 11, 2, 4};
  indexed_iterator(vec.begin() + 4, 4)->second = -1;
  EXPECT_THAT(vec[4], -1);
}