Add object-map test case

test/TestCases/napi-dotnet/object_map.js

@@ -0,0 +1,28 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+
+// Test the JSRuntimeContext "object map" which keeps track of JS wrapper objects
+// for corresponding .NET objects.
+
+const assert = require('assert');
+
+/** @type {import('./napi-dotnet')} */
+const binding = require('../common').binding;
+
+const ComplexTypes = binding.ComplexTypes;
+assert.strictEqual(typeof ComplexTypes, 'object');
+
+let obj1 = ComplexTypes.classObject;
+assert(obj1);
+
+// The same JS wrapper instance should be returned every time.
+let obj2 = ComplexTypes.classObject;
+assert.strictEqual(obj1, obj2);
+
+// Force the JS wrapper object to be collected.
+obj1 = obj2 = undefined;
+global.gc();
+
+// A new JS wrapper object should be created.
+let obj3 = ComplexTypes.classObject;
+assert(obj3);