test: add a new.target test to addons-napi (#452)

N-API testing for new.target is lacking. Rectify this.

Author: boingoing

Diff for: test/addons-napi/test_new_target/binding.c

@@ -0,0 +1,72 @@
+#include <node_api.h>
+#include "../common.h"
+
+napi_value BaseClass(napi_env env, napi_callback_info info) {
+  napi_value newTargetArg;
+  NAPI_CALL(env, napi_get_new_target(env, info, &newTargetArg));
+  napi_value thisArg;
+  NAPI_CALL(env, napi_get_cb_info(env, info, NULL, NULL, &thisArg, NULL));
+  napi_value undefined;
+  NAPI_CALL(env, napi_get_undefined(env, &undefined));
+
+  // this !== new.target since we are being invoked through super()
+  bool result;
+  NAPI_CALL(env, napi_strict_equals(env, newTargetArg, thisArg, &result));
+  NAPI_ASSERT(env, !result, "this !== new.target");
+
+  // new.target !== undefined because we should be called as a new expression
+  NAPI_CALL(env, napi_strict_equals(env, newTargetArg, undefined, &result));
+  NAPI_ASSERT(env, !result, "new.target !== undefined");
+
+  return thisArg;
+}
+
+napi_value Constructor(napi_env env, napi_callback_info info) {
+  bool result;
+  napi_value newTargetArg;
+  NAPI_CALL(env, napi_get_new_target(env, info, &newTargetArg));
+  size_t argc = 1;
+  napi_value argv;
+  napi_value thisArg;
+  NAPI_CALL(env, napi_get_cb_info(env, info, &argc, &argv, &thisArg, NULL));
+  napi_value undefined;
+  NAPI_CALL(env, napi_get_undefined(env, &undefined));
+
+  // new.target !== undefined because we should be called as a new expression
+  NAPI_CALL(env, napi_strict_equals(env, newTargetArg, undefined, &result));
+  NAPI_ASSERT(env, !result, "new.target !== undefined");
+  
+  // arguments[0] should be Constructor itself (test harness passed it)
+  NAPI_CALL(env, napi_strict_equals(env, newTargetArg, argv, &result));
+  NAPI_ASSERT(env, result, "new.target === Constructor");
+
+  return thisArg;
+}
+
+napi_value OrdinaryFunction(napi_env env, napi_callback_info info) {
+  bool result;
+  napi_value newTargetArg;
+  NAPI_CALL(env, napi_get_new_target(env, info, &newTargetArg));
+  napi_value undefined;
+  NAPI_CALL(env, napi_get_undefined(env, &undefined));
+
+  // new.target === undefined because we are not called as a new expression
+  NAPI_CALL(env, napi_strict_equals(env, newTargetArg, undefined, &result));
+  NAPI_ASSERT(env, result, "new.target === undefined");
+
+  napi_value _true;
+  NAPI_CALL(env, napi_get_boolean(env, true, &_true));
+  return _true;
+}
+
+napi_value Init(napi_env env, napi_value exports) {
+  const napi_property_descriptor desc[] = {
+    DECLARE_NAPI_PROPERTY("BaseClass", BaseClass),
+    DECLARE_NAPI_PROPERTY("OrdinaryFunction", OrdinaryFunction),
+    DECLARE_NAPI_PROPERTY("Constructor", Constructor)
+  };
+  NAPI_CALL(env, napi_define_properties(env, exports, 3, desc));
+  return exports;
+}
+
+NAPI_MODULE(NODE_GYP_MODULE_NAME, Init)

Diff for: test/addons-napi/test_new_target/binding.gyp

@@ -0,0 +1,9 @@
+{
+  'targets': [
+    {
+      'target_name': 'binding',
+      'defines': [ 'V8_DEPRECATION_WARNINGS=1' ],
+      'sources': [ 'binding.c' ]
+    }
+  ]
+}

Diff for: test/addons-napi/test_new_target/test.js

@@ -0,0 +1,21 @@
+'use strict';
+
+const common = require('../../common');
+const assert = require('assert');
+const binding = require(`./build/${common.buildType}/binding`);
+
+class Class extends binding.BaseClass {
+  constructor() {
+    super();
+    this.method();
+  }
+  method() {
+    this.ok = true;
+  }
+}
+
+assert.ok(new Class() instanceof binding.BaseClass);
+assert.ok(new Class().ok);
+assert.ok(binding.OrdinaryFunction());
+assert.ok(
+  new binding.Constructor(binding.Constructor) instanceof binding.Constructor);