[PR #11301/815901f6 backport][3.12] Clean up redundant code and stale comments from PR #11290 (#11318)

**This is a backport of PR #11301 as merged into master
(815901f).**

Co-authored-by: J. Nick Koston <[email protected]>

Author: patchback[bot]

aiohttp/payload.py

@@ -559,11 +559,7 @@ def size(self) -> Optional[int]:
             # By storing the start position, we ensure the size calculation always
             # returns the correct total size for any subsequent use.
             if self._start_position is None:
-                try:
-                    self._start_position = self._value.tell()
-                except (OSError, AttributeError):
-                    # Can't get position, can't determine size
-                    return None
+                self._start_position = self._value.tell()
 
             # Return the total size from the start position
             # This ensures Content-Length is correct even after reading

tests/test_client_functional.py

@@ -5298,8 +5298,8 @@ async def test_file_upload_307_308_redirect(
 ) -> None:
     """Test that file uploads work correctly with 307/308 redirects.
 
-    This demonstrates the bug where file payloads get incorrect Content-Length
-    on redirect because the file position isn't reset.
+    This verifies that file payloads maintain correct Content-Length
+    on redirect by properly handling the file position.
     """
     received_bodies: list[bytes] = []
 

tests/test_payload.py

@@ -1283,8 +1283,9 @@ def open_file() -> TextIO:
 async def test_iobase_payload_size_after_reading(tmp_path: Path) -> None:
     """Test that IOBasePayload.size returns correct size after file has been read.
 
-    This demonstrates the bug where size calculation doesn't account for
-    the current file position, causing issues with 307/308 redirects.
+    This verifies that size calculation properly accounts for the initial
+    file position, which is critical for 307/308 redirects where the same
+    payload instance is reused.
     """
     # Create a test file with known content
     test_file = tmp_path / "test.txt"
@@ -1306,14 +1307,12 @@ async def test_iobase_payload_size_after_reading(tmp_path: Path) -> None:
         assert len(writer.buffer) == expected_size
 
         # Second size check - should still return full file size
-        # but currently returns 0 because file position is at EOF
-        assert p.size == expected_size  # This assertion fails!
+        assert p.size == expected_size
 
         # Attempting to write again should write the full content
-        # but currently writes nothing because file is at EOF
         writer2 = BufferWriter()
         await p.write(writer2)
-        assert len(writer2.buffer) == expected_size  # This also fails!
+        assert len(writer2.buffer) == expected_size
     finally:
         await asyncio.to_thread(f.close)