fix(json_wrapper): address review comments

- Initialize json_ in member initializer list for exception safety
- Add missing #include <string> in test file
- Fix Copy Non-owning Wrapper test to verify deep copy by scoping w2 outside w1

Signed-off-by: LHT129 <tianlan.lht@antgroup.com>

Author: LHT129

src/json_wrapper.cpp

@@ -30,12 +30,9 @@ JsonWrapper::~JsonWrapper() {
     }
 }
 
-JsonWrapper::JsonWrapper(const JsonWrapper& other) : owns_json_(true) {
-    if (other.json_ != nullptr) {
-        json_ = new nlohmann::json(*other.json_);
-    } else {
-        json_ = new nlohmann::json();
-    }
+JsonWrapper::JsonWrapper(const JsonWrapper& other)
+    : json_(other.json_ ? new nlohmann::json(*other.json_) : new nlohmann::json()),
+      owns_json_(true) {
 }
 
 JsonWrapper&

tests/test_json_wrapper.cpp

@@ -13,6 +13,7 @@
 // limitations under the License.
 
 #include <catch2/catch_test_macros.hpp>
+#include <string>
 
 #include "json_wrapper.h"
 
@@ -53,12 +54,11 @@ TEST_CASE("JsonWrapper Copy Nested Json", "[ft][json_wrapper]") {
 }
 
 TEST_CASE("JsonWrapper Copy Non-owning Wrapper", "[ft][json_wrapper]") {
-    std::string copied_value;
+    vsag::JsonWrapper w2 = vsag::JsonWrapper();
     {
         auto w1 = vsag::JsonWrapper::Parse(R"({"key": "value"})");
         vsag::JsonWrapper sub = w1["key"];
-        vsag::JsonWrapper w2 = sub;
-        copied_value = w2.GetString();
+        w2 = sub;
     }
-    CHECK(copied_value == "value");
+    CHECK(w2.GetString() == "value");
 }