node-api: add nested object wrap and napi_ref test

Test that an napi_ref can be nested inside another ObjectWrap. The test
shows a critical case where a finalizer deletes an `napi_ref` whose
finalizer is also scheduled.

PR-URL: https://github.com/nodejs/node/pull/57981
Reviewed-By: Vladimir Morozov <vmorozov@microsoft.com>
Reviewed-By: Michael Dawson <midawson@redhat.com>

test/js-native-api/6_object_wrap/binding.gyp

@@ -1,17 +1,28 @@
 {
   "targets": [
     {
-      "target_name": "6_object_wrap",
+      "target_name": "myobject",
       "sources": [
-        "6_object_wrap.cc"
+        "myobject.cc",
+        "myobject.h",
       ]
     },
     {
-      "target_name": "6_object_wrap_basic_finalizer",
+      "target_name": "myobject_basic_finalizer",
       "defines": [ "NAPI_EXPERIMENTAL" ],
       "sources": [
-        "6_object_wrap.cc"
-      ]
-    }
+        "myobject.cc",
+        "myobject.h",
+      ]
+    },
+    {
+      "target_name": "nested_wrap",
+      # Test without basic finalizers as it schedules differently.
+      "defines": [ "NAPI_VERSION=10" ],
+      "sources": [
+        "nested_wrap.cc",
+        "nested_wrap.h",
+      ],
+    },
   ]
 }

test/js-native-api/6_object_wrap/myobject.cc

@@ -1,7 +1,7 @@
+#include "myobject.h"
 #include "../common.h"
 #include "../entry_point.h"
 #include "assert.h"
-#include "myobject.h"
 
 typedef int32_t FinalizerData;
 
@@ -10,7 +10,9 @@ napi_ref MyObject::constructor;
 MyObject::MyObject(double value)
     : value_(value), env_(nullptr), wrapper_(nullptr) {}
 
-MyObject::~MyObject() { napi_delete_reference(env_, wrapper_); }
+MyObject::~MyObject() {
+  napi_delete_reference(env_, wrapper_);
+}
 
 void MyObject::Destructor(node_api_basic_env env,
                           void* nativeObject,
@@ -27,23 +29,35 @@ void MyObject::Destructor(node_api_basic_env env,
 void MyObject::Init(napi_env env, napi_value exports) {
   napi_property_descriptor properties[] = {
       {"value", nullptr, nullptr, GetValue, SetValue, 0, napi_default, 0},
-    { "valueReadonly", nullptr, nullptr, GetValue, nullptr, 0, napi_default,
+      {"valueReadonly",
+       nullptr,
+       nullptr,
+       GetValue,
+       nullptr,
+       0,
+       napi_default,
        0},
       DECLARE_NODE_API_PROPERTY("plusOne", PlusOne),
       DECLARE_NODE_API_PROPERTY("multiply", Multiply),
   };
 
   napi_value cons;
-  NODE_API_CALL_RETURN_VOID(env, napi_define_class(
-      env, "MyObject", -1, New, nullptr,
+  NODE_API_CALL_RETURN_VOID(
+      env,
+      napi_define_class(env,
+                        "MyObject",
+                        -1,
+                        New,
+                        nullptr,
                         sizeof(properties) / sizeof(napi_property_descriptor),
-      properties, &cons));
+                        properties,
+                        &cons));
 
   NODE_API_CALL_RETURN_VOID(env,
                             napi_create_reference(env, cons, 1, &constructor));
 
-  NODE_API_CALL_RETURN_VOID(env,
-      napi_set_named_property(env, exports, "MyObject", cons));
+  NODE_API_CALL_RETURN_VOID(
+      env, napi_set_named_property(env, exports, "MyObject", cons));
 }
 
 napi_value MyObject::New(napi_env env, napi_callback_info info) {
@@ -71,8 +85,12 @@ napi_value MyObject::New(napi_env env, napi_callback_info info) {
 
     obj->env_ = env;
     NODE_API_CALL(env,
-        napi_wrap(env, _this, obj, MyObject::Destructor,
-            nullptr /* finalize_hint */, &obj->wrapper_));
+                  napi_wrap(env,
+                            _this,
+                            obj,
+                            MyObject::Destructor,
+                            nullptr /* finalize_hint */,
+                            &obj->wrapper_));
 
     return _this;
   }

test/js-native-api/6_object_wrap/nested_wrap.cc

@@ -0,0 +1,99 @@
+#include "nested_wrap.h"
+#include "../common.h"
+#include "../entry_point.h"
+
+napi_ref NestedWrap::constructor{};
+static int finalization_count = 0;
+
+NestedWrap::NestedWrap() {}
+
+NestedWrap::~NestedWrap() {
+  napi_delete_reference(env_, wrapper_);
+
+  // Delete the nested reference as well.
+  napi_delete_reference(env_, nested_);
+}
+
+void NestedWrap::Destructor(node_api_basic_env env,
+                            void* nativeObject,
+                            void* /*finalize_hint*/) {
+  // Once this destructor is called, it cancels all pending
+  // finalizers for the object by deleting the references.
+  NestedWrap* obj = static_cast<NestedWrap*>(nativeObject);
+  delete obj;
+
+  finalization_count++;
+}
+
+void NestedWrap::Init(napi_env env, napi_value exports) {
+  napi_value cons;
+  NODE_API_CALL_RETURN_VOID(
+      env,
+      napi_define_class(
+          env, "NestedWrap", -1, New, nullptr, 0, nullptr, &cons));
+
+  NODE_API_CALL_RETURN_VOID(env,
+                            napi_create_reference(env, cons, 1, &constructor));
+
+  NODE_API_CALL_RETURN_VOID(
+      env, napi_set_named_property(env, exports, "NestedWrap", cons));
+}
+
+napi_value NestedWrap::New(napi_env env, napi_callback_info info) {
+  napi_value new_target;
+  NODE_API_CALL(env, napi_get_new_target(env, info, &new_target));
+  bool is_constructor = (new_target != nullptr);
+  NODE_API_BASIC_ASSERT_BASE(
+      is_constructor, "Constructor called without new", nullptr);
+
+  napi_value this_val;
+  NODE_API_CALL(env,
+                napi_get_cb_info(env, info, 0, nullptr, &this_val, nullptr));
+
+  NestedWrap* obj = new NestedWrap();
+
+  obj->env_ = env;
+  NODE_API_CALL(env,
+                napi_wrap(env,
+                          this_val,
+                          obj,
+                          NestedWrap::Destructor,
+                          nullptr /* finalize_hint */,
+                          &obj->wrapper_));
+
+  // Create a second napi_ref to be deleted in the destructor.
+  NODE_API_CALL(env,
+                napi_add_finalizer(env,
+                                   this_val,
+                                   obj,
+                                   NestedWrap::Destructor,
+                                   nullptr /* finalize_hint */,
+                                   &obj->nested_));
+
+  return this_val;
+}
+
+static napi_value GetFinalizerCallCount(napi_env env, napi_callback_info info) {
+  napi_value result;
+  NODE_API_CALL(env, napi_create_int32(env, finalization_count, &result));
+  return result;
+}
+
+EXTERN_C_START
+napi_value Init(napi_env env, napi_value exports) {
+  NestedWrap::Init(env, exports);
+
+  napi_property_descriptor descriptors[] = {
+      DECLARE_NODE_API_PROPERTY("getFinalizerCallCount", GetFinalizerCallCount),
+  };
+
+  NODE_API_CALL(
+      env,
+      napi_define_properties(env,
+                             exports,
+                             sizeof(descriptors) / sizeof(*descriptors),
+                             descriptors));
+
+  return exports;
+}
+EXTERN_C_END

test/js-native-api/6_object_wrap/nested_wrap.h

@@ -0,0 +1,33 @@
+#ifndef TEST_JS_NATIVE_API_6_OBJECT_WRAP_NESTED_WRAP_H_
+#define TEST_JS_NATIVE_API_6_OBJECT_WRAP_NESTED_WRAP_H_
+
+#include <js_native_api.h>
+
+/**
+ * Test that an napi_ref can be nested inside another ObjectWrap.
+ *
+ * This test shows a critical case where a finalizer deletes an napi_ref
+ * whose finalizer is also scheduled.
+ */
+
+class NestedWrap {
+ public:
+  static void Init(napi_env env, napi_value exports);
+  static void Destructor(node_api_basic_env env,
+                         void* nativeObject,
+                         void* finalize_hint);
+
+ private:
+  explicit NestedWrap();
+  ~NestedWrap();
+
+  static napi_value New(napi_env env, napi_callback_info info);
+
+  static napi_ref constructor;
+
+  napi_env env_{};
+  napi_ref wrapper_{};
+  napi_ref nested_{};
+};
+
+#endif  // TEST_JS_NATIVE_API_6_OBJECT_WRAP_NESTED_WRAP_H_

test/js-native-api/6_object_wrap/nested_wrap.js

@@ -0,0 +1,20 @@
+// Flags: --expose-gc
+
+'use strict';
+const common = require('../../common');
+const { gcUntil } = require('../../common/gc');
+const assert = require('assert');
+const addon = require(`./build/${common.buildType}/nested_wrap`);
+
+// This test verifies that ObjectWrap and napi_ref can be nested and finalized
+// correctly with a non-basic finalizer.
+(() => {
+  let obj = new addon.NestedWrap();
+  obj = null;
+  // Silent eslint about unused variables.
+  assert.strictEqual(obj, null);
+})();
+
+gcUntil('object-wrap-ref', () => {
+  return addon.getFinalizerCallCount() === 1;
+});

test/js-native-api/6_object_wrap/test-basic-finalizer.js

@@ -3,7 +3,7 @@
 'use strict';
 const common = require('../../common');
 const assert = require('assert');
-const addon = require(`./build/${common.buildType}/6_object_wrap_basic_finalizer`);
+const addon = require(`./build/${common.buildType}/myobject_basic_finalizer`);
 
 // This test verifies that ObjectWrap can be correctly finalized with a node_api_basic_finalizer
 // in the current JS loop tick

test/js-native-api/6_object_wrap/test-object-wrap-ref.js

@@ -2,7 +2,7 @@
 
 'use strict';
 const common = require('../../common');
-const addon = require(`./build/${common.buildType}/6_object_wrap`);
+const addon = require(`./build/${common.buildType}/myobject`);
 const { gcUntil } = require('../../common/gc');
 
 (function scope() {

test/js-native-api/6_object_wrap/test.js

@@ -1,7 +1,7 @@
 'use strict';
 const common = require('../../common');
 const assert = require('assert');
-const addon = require(`./build/${common.buildType}/6_object_wrap`);
+const addon = require(`./build/${common.buildType}/myobject`);
 
 const getterOnlyErrorRE =
   /^TypeError: Cannot set property .* of #<.*> which has only a getter$/;