1 files changed, 8 insertions, 1 deletions
diff --git a/libcxx/test/std/strings/basic.string/string.capacity/reserve.pass.cpp b/libcxx/test/std/strings/basic.string/string.capacity/reserve.pass.cpp
index 7210152ea3c..8b9dc13db83 100644
--- a/libcxx/test/std/strings/basic.string/string.capacity/reserve.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.capacity/reserve.pass.cpp
@@ -9,7 +9,9 @@
 
 // <string>
 
-// void reserve(size_type res_arg=0);
+// Split into two calls for C++20
+// void reserve();
+// void reserve(size_type res_arg);
 
 #include <string>
 #include <stdexcept>
@@ -44,6 +46,9 @@ test(S s, typename S::size_type res_arg)
         assert(s == s0);
         assert(s.capacity() >= res_arg);
         assert(s.capacity() >= s.size());
+#if TEST_STD_VER > 17
+        assert(s.capacity() >= old_cap); // resize never shrinks as of P0966
+#endif
     }
 #ifndef TEST_HAS_NO_EXCEPTIONS
     else
@@ -90,6 +95,7 @@ int main()
     test(s, 10);
     test(s, 50);
     test(s, 100);
+    test(s, 1000);
     test(s, S::npos);
     }
     }
@@ -121,6 +127,7 @@ int main()
     test(s, 10);
     test(s, 50);
     test(s, 100);
+    test(s, 1000);
     test(s, S::npos);
     }
     }