Add all tests for indexed_iterator.

test/indexed_iterator_test.cxx

@@ -1,9 +1,12 @@
 #include "iterator/indexed_iterator.hpp"
 
+#include <map>
 #include <vector>
 
 #include <gmock/gmock.h>
 
+#include "iterator/end_aware_iterator.hpp"
+
 using idx_iterator = iterator::indexed_iterator<std::vector<int>::iterator>;
 
 // TODO: This ought to be implemented as a compiles-test
@@ -22,9 +25,85 @@ TEST(IndexedIteratorTest, CanLieAboutIndex) {
 TEST(IndexedIteratorTest, FakeIndexDoesntEffectEqualityCheck) {
   std::vector<int> vec{5, 3, 2, 8, 9, 11, 2, 4};
   EXPECT_THAT(idx_iterator(vec.begin()), idx_iterator(vec.begin(), 3));
+  EXPECT_THAT(idx_iterator(vec.begin()) + 3,
+              testing::Ne(idx_iterator(vec.begin(), 3)));
 }
 
-TEST(IndexedIteratorTest, TreatsVectorIteratorAsMapIdxToValue) {
+TEST(IndexedIteratorTest, IffBaseIteratorEmptyIsEndThenEmptyIsEnd) {
+  std::vector<int> vec{5, 3, 2, 8, 9, 11, 2, 4};
+  EXPECT_THAT(idx_iterator(), testing::Ne(idx_iterator(vec.end())));
+  iterator::end_aware_iterator<decltype(vec.end())> end(vec.end());
+  EXPECT_THAT(iterator::indexed_iterator<decltype(end)>(),
+              iterator::indexed_iterator<decltype(end)>(end));
+}
+
+TEST(IndexedIteratorTest, CanCompareIteratorOrder) {
+  std::vector<int> vec{5, 3, 2, 8, 9, 11, 2, 4};
+  idx_iterator const begin(vec.begin());
+  idx_iterator const it = begin + 3;
+  EXPECT_THAT(begin, testing::Lt(it));
+  EXPECT_THAT(begin, testing::Le(it));
+  EXPECT_THAT(it, testing::Le(it));
+  EXPECT_THAT(it, testing::Gt(begin));
+  EXPECT_THAT(it, testing::Ge(begin));
+  EXPECT_THAT(it, testing::Ge(it));
+}
+
+TEST(IndexedIteratorTest, PreIncrementAdvancesIterator) {
+  std::vector<int> vec{5, 3, 2, 8, 9, 11, 2, 4};
+  idx_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};
+  idx_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};
+  idx_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};
+  idx_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};
+  idx_iterator const begin(vec.begin());
+  idx_iterator it = begin;
+  it += 4;
+  EXPECT_THAT(std::distance(begin, it), 4);
+}
+
+TEST(IndexedIteratorTest, CanWalkNStepsBackwards) {
+  std::vector<int> vec{5, 3, 2, 8, 9, 11, 2, 4};
+  idx_iterator const end(vec.end());
+  idx_iterator it = end;
+  it -= 4;
+  EXPECT_THAT(std::distance(it, end), 4);
+}
+
+TEST(IndexedIteratorTest, RandomAccessIsPassthrough) {
+  std::vector<int> vec{5, 3, 2, 8, 9, 11, 2, 4};
+  EXPECT_THAT(idx_iterator(vec.begin()) + 4, idx_iterator(vec.begin() + 4));
+  EXPECT_THAT(idx_iterator(vec.end()) - 4, idx_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}};
@@ -34,6 +113,16 @@ TEST(IndexedIteratorTest, TreatsVectorIteratorAsMapIdxToValue) {
   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(idx_iterator(vec.begin()),
+                                  idx_iterator(vec.end()));
+  EXPECT_THAT(result, expected);
+}
+
 TEST(IndexedIteratorTest, CanMutatePointedToData) {
   std::vector<int> vec{5, 3, 2, 8, 9, 11, 2, 4};
   idx_iterator(vec.begin() + 4, 4)->second = -1;