1 files changed, 53 insertions, 0 deletions
diff --git a/absl/container/flat_hash_map_test.cc b/absl/container/flat_hash_map_test.cc
index eaa86925..08915e20 100644
--- a/absl/container/flat_hash_map_test.cc
+++ b/absl/container/flat_hash_map_test.cc
@@ -45,6 +45,7 @@ using ::testing::_;
 using ::testing::IsEmpty;
 using ::testing::Pair;
 using ::testing::UnorderedElementsAre;
+using ::testing::UnorderedElementsAreArray;
 
 // Check that absl::flat_hash_map works in a global constructor.
 struct BeforeMain {
@@ -307,6 +308,58 @@ TEST(FlatHashMap, EraseIf) {
   }
 }
 
+TEST(FlatHashMap, CForEach) {
+  flat_hash_map<int, int> m;
+  std::vector<std::pair<int, int>> expected;
+  for (int i = 0; i < 100; ++i) {
+    {
+      SCOPED_TRACE("mutable object iteration");
+      std::vector<std::pair<int, int>> v;
+      absl::container_internal::c_for_each_fast(
+          m, [&v](std::pair<const int, int>& p) { v.push_back(p); });
+      EXPECT_THAT(v, UnorderedElementsAreArray(expected));
+    }
+    {
+      SCOPED_TRACE("const object iteration");
+      std::vector<std::pair<int, int>> v;
+      const flat_hash_map<int, int>& cm = m;
+      absl::container_internal::c_for_each_fast(
+          cm, [&v](const std::pair<const int, int>& p) { v.push_back(p); });
+      EXPECT_THAT(v, UnorderedElementsAreArray(expected));
+    }
+    {
+      SCOPED_TRACE("const object iteration");
+      std::vector<std::pair<int, int>> v;
+      absl::container_internal::c_for_each_fast(
+          flat_hash_map<int, int>(m),
+          [&v](std::pair<const int, int>& p) { v.push_back(p); });
+      EXPECT_THAT(v, UnorderedElementsAreArray(expected));
+    }
+    m[i] = i;
+    expected.emplace_back(i, i);
+  }
+}
+
+TEST(FlatHashMap, CForEachMutate) {
+  flat_hash_map<int, int> s;
+  std::vector<std::pair<int, int>> expected;
+  for (int i = 0; i < 100; ++i) {
+    std::vector<std::pair<int, int>> v;
+    absl::container_internal::c_for_each_fast(
+        s, [&v](std::pair<const int, int>& p) {
+          v.push_back(p);
+          p.second++;
+        });
+    EXPECT_THAT(v, UnorderedElementsAreArray(expected));
+    for (auto& p : expected) {
+      p.second++;
+    }
+    EXPECT_THAT(s, UnorderedElementsAreArray(expected));
+    s[i] = i;
+    expected.emplace_back(i, i);
+  }
+}
+
 // This test requires std::launder for mutable key access in node handles.
 #if defined(__cpp_lib_launder) && __cpp_lib_launder >= 201606
 TEST(FlatHashMap, NodeHandleMutableKeyAccess) {