fix: close file handle warning (#715)

* fix: close fd warning

* adding changeset

* moving fs.close to finally block

* mock .close for test

* fix tests

---------

Co-authored-by: Praveen Gupta <pravgupt@amazon.com>

.changeset/fresh-lobsters-cheer.md

@@ -0,0 +1,5 @@
+---
+'@aws-amplify/platform-core': patch
+---
+
+close file handle after reading config

packages/platform-core/src/config/local_configuration_controller.test.ts

@@ -7,16 +7,20 @@ void describe('config controller', () => {
   const mockedFsReadFile = mock.method(fs, 'readFile');
   const mockedFsWriteFile = mock.method(fs, 'writeFile');
   const mockedFsOpen = mock.method(fs, 'open');
+  const mockedFdClose = mock.fn();
 
   beforeEach(() => {
     mockedFsReadFile.mock.resetCalls();
     mockedFsWriteFile.mock.resetCalls();
     mockedFsOpen.mock.resetCalls();
+    mockedFdClose.mock.resetCalls();
   });
 
   void it('if config has not been cached, read from fs', async () => {
     mockedFsOpen.mock.mockImplementationOnce(() => {
-      return Promise.resolve();
+      return Promise.resolve({
+        close: mockedFdClose,
+      });
     });
     mockedFsReadFile.mock.mockImplementationOnce(function () {
       return Promise.resolve('{"hello": 123}');
@@ -26,6 +30,7 @@ void describe('config controller', () => {
     assert.strictEqual(resolvedValue, undefined);
     assert.strictEqual(mockedFsOpen.mock.callCount(), 1);
     assert.strictEqual(mockedFsReadFile.mock.callCount(), 1);
+    assert.strictEqual(mockedFdClose.mock.callCount(), 1);
   });
 
   void it('should not throw & return undefined with path points to undefined nested object ', async () => {

packages/platform-core/src/config/local_configuration_controller.ts

@@ -30,19 +30,22 @@ export class LocalConfigurationController implements ConfigurationController {
     if (this._store) {
       return this._store;
     }
+    // check if file exists & readable.
+    let fd;
+
     try {
-      // check if file exists & readable.
-      const fd = await fs.open(
+      fd = await fs.open(
         this.configFilePath,
         fs.constants.F_OK,
         fs.constants.O_RDWR
       );
-
       const fileContent = await fs.readFile(fd, 'utf-8');
       this._store = JSON.parse(fileContent);
     } catch {
       this._store = {};
       await this.write();
+    } finally {
+      await fd?.close();
     }
     return this._store;
   }