1 files changed, 34 insertions, 0 deletions
diff --git a/llvm/unittests/ADT/IteratorTest.cpp b/llvm/unittests/ADT/IteratorTest.cpp
index de0a6710789..902ddfb49f2 100644
--- a/llvm/unittests/ADT/IteratorTest.cpp
+++ b/llvm/unittests/ADT/IteratorTest.cpp
@@ -328,6 +328,40 @@ TEST(ZipIteratorTest, ZipFirstBasic) {
   EXPECT_EQ(iters, 4u);
 }
 
+TEST(ZipIteratorTest, ZipLongestBasic) {
+  using namespace std;
+  const vector<unsigned> pi{3, 1, 4, 1, 5, 9};
+  const vector<StringRef> e{"2", "7", "1", "8"};
+
+  {
+    // Check left range longer than right.
+    const vector<tuple<Optional<unsigned>, Optional<StringRef>>> expected{
+        make_tuple(3, StringRef("2")), make_tuple(1, StringRef("7")),
+        make_tuple(4, StringRef("1")), make_tuple(1, StringRef("8")),
+        make_tuple(5, None),           make_tuple(9, None)};
+    size_t iters = 0;
+    for (auto tup : zip_longest(pi, e)) {
+      EXPECT_EQ(tup, expected[iters]);
+      iters += 1;
+    }
+    EXPECT_EQ(iters, expected.size());
+  }
+
+  {
+    // Check right range longer than left.
+    const vector<tuple<Optional<StringRef>, Optional<unsigned>>> expected{
+        make_tuple(StringRef("2"), 3), make_tuple(StringRef("7"), 1),
+        make_tuple(StringRef("1"), 4), make_tuple(StringRef("8"), 1),
+        make_tuple(None, 5),           make_tuple(None, 9)};
+    size_t iters = 0;
+    for (auto tup : zip_longest(e, pi)) {
+      EXPECT_EQ(tup, expected[iters]);
+      iters += 1;
+    }
+    EXPECT_EQ(iters, expected.size());
+  }
+}
+
 TEST(ZipIteratorTest, Mutability) {
   using namespace std;
   const SmallVector<unsigned, 4> pi{3, 1, 4, 1, 5, 9};