1 files changed, 55 insertions, 4 deletions

diff --git a/third_party/abseil-cpp/absl/strings/internal/resize_uninitialized_test.cc b/third_party/abseil-cpp/absl/strings/internal/resize_uninitialized_test.cc
index 0f8b3c2a95..ad1b9c58f3 100644
--- a/third_party/abseil-cpp/absl/strings/internal/resize_uninitialized_test.cc
+++ b/third_party/abseil-cpp/absl/strings/internal/resize_uninitialized_test.cc
@@ -19,64 +19,115 @@
 namespace {
 
 int resize_call_count = 0;
+int append_call_count = 0;
 
 // A mock string class whose only purpose is to track how many times its
-// resize() method has been called.
+// resize()/append() methods have been called.
 struct resizable_string {
+  using value_type = char;
   size_t size() const { return 0; }
+  size_t capacity() const { return 0; }
   char& operator[](size_t) {
     static char c = '\0';
     return c;
   }
   void resize(size_t) { resize_call_count += 1; }
+  void append(size_t, value_type) { append_call_count += 1; }
+  void reserve(size_t) {}
+  resizable_string& erase(size_t = 0, size_t = 0) { return *this; }
 };
 
 int resize_default_init_call_count = 0;
+int append_default_init_call_count = 0;
 
 // A mock string class whose only purpose is to track how many times its
-// resize() and __resize_default_init() methods have been called.
-struct resize_default_init_string {
+// resize()/__resize_default_init()/append()/__append_default_init() methods
+// have been called.
+struct default_init_string {
   size_t size() const { return 0; }
+  size_t capacity() const { return 0; }
   char& operator[](size_t) {
     static char c = '\0';
     return c;
   }
   void resize(size_t) { resize_call_count += 1; }
   void __resize_default_init(size_t) { resize_default_init_call_count += 1; }
+  void __append_default_init(size_t) { append_default_init_call_count += 1; }
+  void reserve(size_t) {}
+  default_init_string& erase(size_t = 0, size_t = 0) { return *this; }
 };
 
 TEST(ResizeUninit, WithAndWithout) {
   resize_call_count = 0;
+  append_call_count = 0;
   resize_default_init_call_count = 0;
+  append_default_init_call_count = 0;
   {
     resizable_string rs;
 
     EXPECT_EQ(resize_call_count, 0);
+    EXPECT_EQ(append_call_count, 0);
     EXPECT_EQ(resize_default_init_call_count, 0);
+    EXPECT_EQ(append_default_init_call_count, 0);
     EXPECT_FALSE(
         absl::strings_internal::STLStringSupportsNontrashingResize(&rs));
     EXPECT_EQ(resize_call_count, 0);
+    EXPECT_EQ(append_call_count, 0);
     EXPECT_EQ(resize_default_init_call_count, 0);
+    EXPECT_EQ(append_default_init_call_count, 0);
     absl::strings_internal::STLStringResizeUninitialized(&rs, 237);
     EXPECT_EQ(resize_call_count, 1);
+    EXPECT_EQ(append_call_count, 0);
     EXPECT_EQ(resize_default_init_call_count, 0);
+    EXPECT_EQ(append_default_init_call_count, 0);
+    absl::strings_internal::STLStringResizeUninitializedAmortized(&rs, 1000);
+    EXPECT_EQ(resize_call_count, 1);
+    EXPECT_EQ(append_call_count, 1);
+    EXPECT_EQ(resize_default_init_call_count, 0);
+    EXPECT_EQ(append_default_init_call_count, 0);
   }
 
   resize_call_count = 0;
+  append_call_count = 0;
   resize_default_init_call_count = 0;
+  append_default_init_call_count = 0;
   {
-    resize_default_init_string rus;
+    default_init_string rus;
 
     EXPECT_EQ(resize_call_count, 0);
+    EXPECT_EQ(append_call_count, 0);
     EXPECT_EQ(resize_default_init_call_count, 0);
+    EXPECT_EQ(append_default_init_call_count, 0);
     EXPECT_TRUE(
         absl::strings_internal::STLStringSupportsNontrashingResize(&rus));
     EXPECT_EQ(resize_call_count, 0);
+    EXPECT_EQ(append_call_count, 0);
     EXPECT_EQ(resize_default_init_call_count, 0);
+    EXPECT_EQ(append_default_init_call_count, 0);
     absl::strings_internal::STLStringResizeUninitialized(&rus, 237);
     EXPECT_EQ(resize_call_count, 0);
+    EXPECT_EQ(append_call_count, 0);
+    EXPECT_EQ(resize_default_init_call_count, 1);
+    EXPECT_EQ(append_default_init_call_count, 0);
+    absl::strings_internal::STLStringResizeUninitializedAmortized(&rus, 1000);
+    EXPECT_EQ(resize_call_count, 0);
+    EXPECT_EQ(append_call_count, 0);
     EXPECT_EQ(resize_default_init_call_count, 1);
+    EXPECT_EQ(append_default_init_call_count, 1);
+  }
+}
+
+TEST(ResizeUninit, Amortized) {
+  std::string str;
+  size_t prev_cap = str.capacity();
+  int cap_increase_count = 0;
+  for (int i = 0; i < 1000; ++i) {
+    absl::strings_internal::STLStringResizeUninitializedAmortized(&str, i);
+    size_t new_cap = str.capacity();
+    if (new_cap > prev_cap) ++cap_increase_count;
+    prev_cap = new_cap;
   }
+  EXPECT_LT(cap_increase_count, 50);
 }
 
 }  // namespace