Handle shutdown on grid adapters (#5943)

* Handle shutdown on grid adapters

* Add tests

* Fix postgres test

src/Adapters/Files/GridFSBucketAdapter.js

@@ -32,7 +32,10 @@ export class GridFSBucketAdapter extends FilesAdapter {
       this._connectionPromise = MongoClient.connect(
         this._databaseURI,
         this._mongoOptions
-      ).then(client => client.db(client.s.options.dbName));
+      ).then(client => {
+        this._client = client;
+        return client.db(client.s.options.dbName);
+      });
     }
     return this._connectionPromise;
   }
@@ -98,6 +101,13 @@ export class GridFSBucketAdapter extends FilesAdapter {
     const bucket = await this._getBucket();
     return bucket.openDownloadStreamByName(filename);
   }
+
+  handleShutdown() {
+    if (!this._client) {
+      return Promise.resolve();
+    }
+    return this._client.close(false);
+  }
 }
 
 export default GridFSBucketAdapter;

src/Adapters/Files/GridStoreAdapter.js

@@ -33,7 +33,10 @@ export class GridStoreAdapter extends FilesAdapter {
       this._connectionPromise = MongoClient.connect(
         this._databaseURI,
         this._mongoOptions
-      ).then(client => client.db(client.s.options.dbName));
+      ).then(client => {
+        this._client = client;
+        return client.db(client.s.options.dbName);
+      });
     }
     return this._connectionPromise;
   }
@@ -99,6 +102,13 @@ export class GridStoreAdapter extends FilesAdapter {
       });
     });
   }
+
+  handleShutdown() {
+    if (!this._client) {
+      return Promise.resolve();
+    }
+    return this._client.close(false);
+  }
 }
 
 export default GridStoreAdapter;