[libcxx-commits] [libcxx] Improve tests for assign in std::vector (PR #119163)

[Peng Liu via libcxx-commits]

https://github.com/winner245 created https://github.com/llvm/llvm-project/pull/119163

This PR enhances the test coverage for the `assign` function of `std::vector` by adding new tests for several important test cases that were previously missing, as shown in the following table:

| test cases | forward_iterator | input_iterator |
|----------|----------|----------|
| new_size > capacity()   |  Yes  | No  |
| size() < new_size <= capacity()   | No   | No   |
| new_size <= size()    | No   | No   | 

With this patch applied, all missing test cases will be covered. 

>From dc0d8cf37361461b1537d596086e12c3c09e3c95 Mon Sep 17 00:00:00 2001
From: Peng Liu <winner245 at hotmail.com>
Date: Sun, 8 Dec 2024 22:54:51 -0500
Subject: [PATCH] Improve tests for assign in std::vector

---
 .../vector.cons/assign_iter_iter.pass.cpp     | 107 ++++++++++++++++--
 1 file changed, 100 insertions(+), 7 deletions(-)

diff --git a/libcxx/test/std/containers/sequences/vector/vector.cons/assign_iter_iter.pass.cpp b/libcxx/test/std/containers/sequences/vector/vector.cons/assign_iter_iter.pass.cpp
index 9b52885b9bf8d2..bc3cb9127851e9 100644
--- a/libcxx/test/std/containers/sequences/vector/vector.cons/assign_iter_iter.pass.cpp
+++ b/libcxx/test/std/containers/sequences/vector/vector.cons/assign_iter_iter.pass.cpp
@@ -18,17 +18,16 @@
 #include "asan_testing.h"
 #include "test_iterators.h"
 #if TEST_STD_VER >= 11
-#include "emplace_constructible.h"
-#include "container_test_types.h"
+#  include "emplace_constructible.h"
+#  include "container_test_types.h"
 #endif
 
-
 TEST_CONSTEXPR_CXX20 bool test() {
 #if TEST_STD_VER >= 11
   int arr1[] = {42};
   int arr2[] = {1, 101, 42};
-  {
-    using T = EmplaceConstructibleMoveableAndAssignable<int>;
+  { // Test with new_size > capacity() == 0 for forward_iterator, thus reallocation occurs during assign
+    using T  = EmplaceConstructibleMoveableAndAssignable<int>;
     using It = forward_iterator<int*>;
     {
       std::vector<T> v;
@@ -43,8 +42,8 @@ TEST_CONSTEXPR_CXX20 bool test() {
       assert(v[2].value == 42);
     }
   }
-  {
-    using T = EmplaceConstructibleMoveableAndAssignable<int>;
+  { // Test with new_size > capacity() == 0 for input_iterator, thus reallocation occurs during assign
+    using T  = EmplaceConstructibleMoveableAndAssignable<int>;
     using It = cpp17_input_iterator<int*>;
     {
       std::vector<T> v;
@@ -63,6 +62,100 @@ TEST_CONSTEXPR_CXX20 bool test() {
       assert(v[2].value == 42);
     }
   }
+
+  { // Test with new_size < size() for forward_iterator, thus destruction at end occurs during assign
+    using T  = EmplaceConstructibleMoveableAndAssignable<int>;
+    using It = forward_iterator<int*>;
+    {
+      std::vector<T> v;
+      v.reserve(5);
+      for (std::size_t i = 0; i < v.capacity(); ++i)
+        v.emplace_back(99);
+      v.assign(It(arr1), It(std::end(arr1)));
+      assert(v.size() == 1);
+      assert(v[0].value == 42);
+    }
+    {
+      std::vector<T> v;
+      v.reserve(5);
+      for (std::size_t i = 0; i < v.capacity(); ++i)
+        v.emplace_back(99);
+      v.assign(It(arr2), It(std::end(arr2)));
+      assert(v.size() == 3);
+      assert(v[0].value == 1);
+      assert(v[1].value == 101);
+      assert(v[2].value == 42);
+    }
+  }
+  { // Test with new_size < size() for input_iterator, thus destruction at end occurs during assign
+    using T  = EmplaceConstructibleMoveableAndAssignable<int>;
+    using It = cpp17_input_iterator<int*>;
+    {
+      std::vector<T> v;
+      v.reserve(5);
+      for (std::size_t i = 0; i < v.capacity(); ++i)
+        v.emplace_back(99);
+      v.assign(It(arr1), It(std::end(arr1)));
+      assert(v.size() == 1);
+      assert(v[0].value == 42);
+    }
+    {
+      std::vector<T> v;
+      v.reserve(5);
+      for (std::size_t i = 0; i < v.capacity(); ++i)
+        v.emplace_back(99);
+      v.assign(It(arr2), It(std::end(arr2)));
+      assert(v.size() == 3);
+      assert(v[0].value == 1);
+      assert(v[1].value == 101);
+      assert(v[2].value == 42);
+    }
+  }
+
+  { // Test with size() < new_size < capacity() for forward_iterator, thus construction at end occurs during assign
+    using T  = EmplaceConstructibleMoveableAndAssignable<int>;
+    using It = forward_iterator<int*>;
+    {
+      std::vector<T> v;
+      v.reserve(5);
+      v.assign(It(arr1), It(std::end(arr1)));
+      assert(v.size() == 1);
+      assert(v[0].value == 42);
+    }
+    {
+      std::vector<T> v;
+      v.reserve(5);
+      for (std::size_t i = 0; i < 2; ++i)
+        v.emplace_back(99);
+      v.assign(It(arr2), It(std::end(arr2)));
+      assert(v.size() == 3);
+      assert(v[0].value == 1);
+      assert(v[1].value == 101);
+      assert(v[2].value == 42);
+    }
+  }
+  { // Test with size() < new_size < capacity() for inputs_iterator, thus construction at end occurs during assign
+    using T  = EmplaceConstructibleMoveableAndAssignable<int>;
+    using It = cpp17_input_iterator<int*>;
+    {
+      std::vector<T> v;
+      v.reserve(5);
+      v.assign(It(arr1), It(std::end(arr1)));
+      assert(v.size() == 1);
+      assert(v[0].value == 42);
+    }
+    {
+      std::vector<T> v;
+      v.reserve(5);
+      for (std::size_t i = 0; i < 2; ++i)
+        v.emplace_back(99);
+      v.assign(It(arr2), It(std::end(arr2)));
+      assert(v.size() == 3);
+      assert(v[0].value == 1);
+      assert(v[1].value == 101);
+      assert(v[2].value == 42);
+    }
+  }
 #endif
 
   // Test with a number of elements in the source range that is greater than capacity