Fix accessors test to work with Holder unwrapping

To ensure that the Holder of an accessor is indeed an instance of the corret
type, we can't attach the holders to the prototype but have to attach them
to the object itself.

Author: gagern

test/cpp/accessors.cpp

@@ -48,13 +48,13 @@ NAN_MODULE_INIT(SetterGetter::Init) {
   tpl->SetClassName(Nan::New<v8::String>("SetterGetter").ToLocalChecked());
   tpl->InstanceTemplate()->SetInternalFieldCount(1);
   SetPrototypeMethod(tpl, "log", SetterGetter::Log);
-  v8::Local<v8::ObjectTemplate> proto = tpl->PrototypeTemplate();
+  v8::Local<v8::ObjectTemplate> itpl = tpl->InstanceTemplate();
   SetAccessor(
-      proto
+      itpl
     , Nan::New("prop1").ToLocalChecked()
     , SetterGetter::GetProp1);
   SetAccessor(
-      proto
+      itpl
     , Nan::New<v8::String>("prop2").ToLocalChecked()
     , SetterGetter::GetProp2
     , SetterGetter::SetProp2

test/js/accessors-test.js

@@ -11,7 +11,7 @@ const test     = require('tap').test
     , bindings = require('bindings')({ module_root: testRoot, bindings: 'accessors' });
 
 test('accessors', function (t) {
-  t.plan(4)
+  t.plan(7)
   var settergetter = bindings.create()
   t.equal(settergetter.prop1, 'this is property 1')
   t.ok(settergetter.prop2 === '')
@@ -24,4 +24,9 @@ test('accessors', function (t) {
     'Prop2:SETTER(setting a value)\n' +
     'Prop2:GETTER(setting a value)\n'
   )
+  var derived = Object.create(settergetter)
+  t.equal(derived.prop1, 'this is property 1')
+  derived.prop2 = 'setting a new value'
+  t.equal(derived.prop2, 'setting a new value')
+  t.equal(settergetter.prop2, 'setting a new value')
 })