From 2cb994cdc9c0e51319e9059459ac1cccd7730673 Mon Sep 17 00:00:00 2001
From: Christopher Adams <christopher.r.adams@gmail.com>
Date: Mon, 27 Jun 2022 10:44:46 -0400
Subject: [PATCH] Returned future result in S3Transfer's download and upload

- Adds a `return` statement to S3Transfer's methods `upload_file()` and
  `download_file()`.
- This gives them the same return behavior as `copy()`, `upload_fileobj()`,
  and `download_fileobj()` inside `s3/inject.py`. These functions return the
  value for their future objects.
- Returning the value will allow integrations to access metadata
  returned by the service, such as the "ETag" for uploaded entities for
  example.
---
 boto3/s3/transfer.py           | 8 ++++++--
 tests/unit/s3/test_transfer.py | 6 ++++--
 2 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/boto3/s3/transfer.py b/boto3/s3/transfer.py
index 3d572981e0..ee824b1333 100644
--- a/boto3/s3/transfer.py
+++ b/boto3/s3/transfer.py
@@ -276,6 +276,8 @@ def upload_file(
         .. seealso::
             :py:meth:`S3.Client.upload_file`
             :py:meth:`S3.Client.upload_fileobj`
+
+        :returns: The result of the specific manager's upload function.
         """
         if not isinstance(filename, str):
             raise ValueError('Filename must be a string')
@@ -285,7 +287,7 @@ def upload_file(
             filename, bucket, key, extra_args, subscribers
         )
         try:
-            future.result()
+            return future.result()
         # If a client error was raised, add the backwards compatibility layer
         # that raises a S3UploadFailedError. These specific errors were only
         # ever thrown for upload_parts but now can be thrown for any related
@@ -308,6 +310,8 @@ def download_file(
         .. seealso::
             :py:meth:`S3.Client.download_file`
             :py:meth:`S3.Client.download_fileobj`
+
+        :returns: The result of the specific manager's download function.
         """
         if not isinstance(filename, str):
             raise ValueError('Filename must be a string')
@@ -317,7 +321,7 @@ def download_file(
             bucket, key, filename, extra_args, subscribers
         )
         try:
-            future.result()
+            return future.result()
         # This is for backwards compatibility where when retries are
         # exceeded we need to throw the same error from boto3 instead of
         # s3transfer's built in RetriesExceededError as current users are
diff --git a/tests/unit/s3/test_transfer.py b/tests/unit/s3/test_transfer.py
index 9f3456f196..f725831a19 100644
--- a/tests/unit/s3/test_transfer.py
+++ b/tests/unit/s3/test_transfer.py
@@ -141,24 +141,26 @@ def assert_callback_wrapped_in_subscriber(self, call_args):
 
     def test_upload_file(self):
         extra_args = {'ACL': 'public-read'}
-        self.transfer.upload_file(
+        upload_metadata = self.transfer.upload_file(
             'smallfile', 'bucket', 'key', extra_args=extra_args
         )
         self.manager.upload.assert_called_with(
             'smallfile', 'bucket', 'key', extra_args, None
         )
+        self.assertIsNotNone(upload_metadata)
 
     def test_download_file(self):
         extra_args = {
             'SSECustomerKey': 'foo',
             'SSECustomerAlgorithm': 'AES256',
         }
-        self.transfer.download_file(
+        download_metadata = self.transfer.download_file(
             'bucket', 'key', '/tmp/smallfile', extra_args=extra_args
         )
         self.manager.download.assert_called_with(
             'bucket', 'key', '/tmp/smallfile', extra_args, None
         )
+        self.assertIsNotNone(download_metadata)
 
     def test_upload_wraps_callback(self):
         self.transfer.upload_file(