fix: Perform safer checks for toContain(..) in example, and add NitroModules.hasNativeState(value)

example/src/Testers.ts

@@ -68,7 +68,10 @@ export class State<T> {
   toContain(key: keyof T): State<T> {
     if (
       this.result != null &&
-      (this.result[key] != null ||
+      (Object.hasOwn(this.result, key) ||
+        this.result[key] != null ||
+        // @ts-expect-error maybe a TypeScript bug? It's an object, so it's safe
+        (typeof key === 'object' && key in this.result) ||
         Object.keys(this.result).includes(key as string))
     ) {
       this.onPassed()

example/src/utils.ts

@@ -1,3 +1,5 @@
+import { NitroModules } from 'react-native-nitro-modules'
+
 export function stringify(value: unknown): string {
   if (value == null) {
     return 'null'
@@ -19,14 +21,24 @@ export function stringify(value: unknown): string {
       }
       try {
         if ('toString' in value) {
-          const string = value.toString()
-          if (string !== '[object Object]') return string
+          if (Object.hasOwn(value, 'toString')) {
+            // It is some kind of Object that has a toString() method directly.
+            const string = value.toString()
+            if (string !== '[object Object]') return string
+          } else {
+            // It is some kind of Object that has a toString() method somewhere in the prototype chain..
+            // It is _likely_ that this method requires NativeState
+            if (NitroModules.hasNativeState(value)) {
+              // If we have NativeState, toString() will likely work.
+              const string = value.toString()
+              if (string !== '[object Object]') return string
+            }
+          }
         }
-        return `{ ${value} ${Object.keys(value).join(', ')} }`
       } catch {
         // toString() threw - maybe because we accessed it on a prototype.
-        return `{ [Object] ${Object.keys(value).join(', ')} }`
       }
+      return `{ [Object] ${Object.keys(value).join(', ')} }`
     default:
       return `${value}`
   }

packages/react-native-nitro-modules/cpp/entrypoint/HybridNitroModulesProxy.cpp

@@ -21,6 +21,8 @@ void HybridNitroModulesProxy::loadHybridMethods() {
 
     prototype.registerHybridMethod("box", &HybridNitroModulesProxy::box);
 
+    prototype.registerRawHybridMethod("hasNativeState", 1, &HybridNitroModulesProxy::hasNativeState);
+
     prototype.registerHybridGetter("buildType", &HybridNitroModulesProxy::getBuildType);
   });
 }
@@ -43,6 +45,13 @@ std::shared_ptr<BoxedHybridObject> HybridNitroModulesProxy::box(const std::share
   return std::make_shared<BoxedHybridObject>(hybridObject);
 }
 
+jsi::Value HybridNitroModulesProxy::hasNativeState(jsi::Runtime& runtime, const jsi::Value&, const jsi::Value* args, size_t size) {
+  if (size != 1 || !args[0].isObject()) {
+    return false;
+  }
+  return args[0].getObject(runtime).hasNativeState(runtime);
+}
+
 // Build Info
 std::string HybridNitroModulesProxy::getBuildType() {
 #ifdef NITRO_DEBUG

packages/react-native-nitro-modules/cpp/entrypoint/HybridNitroModulesProxy.hpp

@@ -37,6 +37,7 @@ class HybridNitroModulesProxy : public HybridObject {
 
   // Helpers
   std::shared_ptr<BoxedHybridObject> box(const std::shared_ptr<HybridObject>& hybridObject);
+  jsi::Value hasNativeState(jsi::Runtime& runtime, const jsi::Value& thisValue, const jsi::Value* args, size_t size);
 
   // Build Info
   std::string getBuildType();

packages/react-native-nitro-modules/src/NitroModulesProxy.ts

@@ -58,4 +58,9 @@ export interface NitroModulesProxy extends HybridObject {
    * ```
    */
   box<T extends HybridObject>(obj: T): BoxedHybridObject<T>
+
+  /**
+   * Returns whether the given {@linkcode object} has NativeState or not.
+   */
+  hasNativeState(object: unknown): boolean
 }