add: unit and integration testing

app/node_modules/jest-leak-detector/build/index.d.ts

@@ -0,0 +1,20 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+declare class LeakDetector {
+  private _isReferenceBeingHeld;
+  private _shouldGenerateV8HeapSnapshot;
+  private readonly _finalizationRegistry?;
+  constructor(value: unknown, opt?: LeakDetectorOptions);
+  isLeaking(): Promise<boolean>;
+  private _runGarbageCollector;
+}
+export default LeakDetector;
+
+declare interface LeakDetectorOptions {
+  shouldGenerateV8HeapSnapshot: boolean;
+}