fix: prevent global Promise overwrite for thread safety.

Proxy globalThis object in order to prevent JS user space code to override Promise global variable (e.g. mocha does that) aka our Promise Proxy which ensurses that Promises are resolved on the same thread on which they were created.

Author: adrian-niculescu

NativeScript/runtime/PromiseProxy.cpp

@@ -1,12 +1,13 @@
 #include "PromiseProxy.h"
+
 #include "Helpers.h"
 
 using namespace v8;
 
 namespace tns {
 
 void PromiseProxy::Init(v8::Local<v8::Context> context) {
-    std::string source = R"(
+  std::string source = R"(
         // Ensure that Promise callbacks are executed on the
         // same thread on which they were created
         (() => {
@@ -72,18 +73,40 @@ void PromiseProxy::Init(v8::Local<v8::Context> context) {
                     });
                 }
             });
+            globalThis = new Proxy(globalThis, {
+                defineProperty: (target, prop, descriptor) => {
+                    if (prop === 'Promise') {
+                        return true;
+                    }
+                    return Object.defineProperty(target, prop, descriptor);
+                },
+                set: (target, prop, value, receiver) => {
+                    if (prop === 'Promise') {
+                        return true;
+                    }
+    
+                    const descriptor = Object.getOwnPropertyDescriptor(target, prop);
+                    if (descriptor && !descriptor.writable) {
+                        return false;
+                    }
+
+                    target[prop] = value;
+                    return true;
+                }
+            });
         })();
     )";
 
-    Isolate* isolate = context->GetIsolate();
+  Isolate* isolate = context->GetIsolate();
 
-    Local<Script> script;
-    bool success = Script::Compile(context, tns::ToV8String(isolate, source)).ToLocal(&script);
-    tns::Assert(success && !script.IsEmpty(), isolate);
+  Local<Script> script;
+  bool success = Script::Compile(context, tns::ToV8String(isolate, source))
+                     .ToLocal(&script);
+  tns::Assert(success && !script.IsEmpty(), isolate);
 
-    Local<Value> result;
-    success = script->Run(context).ToLocal(&result);
-    tns::Assert(success, isolate);
+  Local<Value> result;
+  success = script->Run(context).ToLocal(&result);
+  tns::Assert(success, isolate);
 }
 
-}
+}  // namespace tns