From 89951ecf658a49cfe477d1a389336f90a043ff2d Mon Sep 17 00:00:00 2001
From: "patchback[bot]" <45432694+patchback[bot]@users.noreply.github.com>
Date: Tue, 10 Sep 2024 19:04:02 +0100
Subject: [PATCH] [PR #9110/b90dd1e4 backport][3.10] Avoid compressing empty
 body (#9108) (#9111)

**This is a backport of PR #9110 as merged into 3.11
(b90dd1e41f77e3296edf8932cc0ec59ab1343463).**

(cherry picked from commit 1d112418a05dcdcabd38590351e78bec8f4a45bc)

Co-authored-by: Sam Bull <git@sambull.org>
---
 CHANGES/9108.bugfix.rst         |  1 +
 aiohttp/client.py               |  4 +--
 aiohttp/client_reqrep.py        |  8 +++---
 tests/test_client_functional.py | 45 ++++++++++++++++++++++++++++++---
 4 files changed, 50 insertions(+), 8 deletions(-)
 create mode 100644 CHANGES/9108.bugfix.rst

diff --git a/CHANGES/9108.bugfix.rst b/CHANGES/9108.bugfix.rst
new file mode 100644
index 00000000000..8be000575e8
--- /dev/null
+++ b/CHANGES/9108.bugfix.rst
@@ -0,0 +1 @@
+Fixed compressed requests failing when no body was provided -- by :user:`Dreamsorcerer`.
diff --git a/aiohttp/client.py b/aiohttp/client.py
index 2814edc31ee..5f9e95f4706 100644
--- a/aiohttp/client.py
+++ b/aiohttp/client.py
@@ -165,7 +165,7 @@ class _RequestOptions(TypedDict, total=False):
     auth: Union[BasicAuth, None]
     allow_redirects: bool
     max_redirects: int
-    compress: Union[str, None]
+    compress: Union[str, bool, None]
     chunked: Union[bool, None]
     expect100: bool
     raise_for_status: Union[None, bool, Callable[[ClientResponse], Awaitable[None]]]
@@ -459,7 +459,7 @@ async def _request(
         auth: Optional[BasicAuth] = None,
         allow_redirects: bool = True,
         max_redirects: int = 10,
-        compress: Optional[str] = None,
+        compress: Union[str, bool, None] = None,
         chunked: Optional[bool] = None,
         expect100: bool = False,
         raise_for_status: Union[
diff --git a/aiohttp/client_reqrep.py b/aiohttp/client_reqrep.py
index 2df43d112cd..93e7b59a8a1 100644
--- a/aiohttp/client_reqrep.py
+++ b/aiohttp/client_reqrep.py
@@ -272,7 +272,7 @@ def __init__(
         cookies: Optional[LooseCookies] = None,
         auth: Optional[BasicAuth] = None,
         version: http.HttpVersion = http.HttpVersion11,
-        compress: Optional[str] = None,
+        compress: Union[str, bool, None] = None,
         chunked: Optional[bool] = None,
         expect100: bool = False,
         loop: Optional[asyncio.AbstractEventLoop] = None,
@@ -503,7 +503,9 @@ def update_cookies(self, cookies: Optional[LooseCookies]) -> None:
 
     def update_content_encoding(self, data: Any) -> None:
         """Set request content encoding."""
-        if data is None:
+        if not data:
+            # Don't compress an empty body.
+            self.compress = None
             return
 
         enc = self.headers.get(hdrs.CONTENT_ENCODING, "").lower()
@@ -714,7 +716,7 @@ async def send(self, conn: "Connection") -> "ClientResponse":
         )
 
         if self.compress:
-            writer.enable_compression(self.compress)
+            writer.enable_compression(self.compress)  # type: ignore[arg-type]
 
         if self.chunked is not None:
             writer.enable_chunking()
diff --git a/tests/test_client_functional.py b/tests/test_client_functional.py
index 9325cc17e48..082db6f3e9a 100644
--- a/tests/test_client_functional.py
+++ b/tests/test_client_functional.py
@@ -12,7 +12,7 @@
 import tarfile
 import time
 import zipfile
-from typing import Any, AsyncIterator, Type
+from typing import Any, AsyncIterator, Optional, Type
 from unittest import mock
 
 import pytest
@@ -31,6 +31,9 @@
     SocketTimeoutError,
     TooManyRedirects,
 )
+from aiohttp.client_reqrep import ClientRequest
+from aiohttp.connector import Connection
+from aiohttp.http_writer import StreamWriter
 from aiohttp.pytest_plugin import AiohttpClient, AiohttpServer, TestClient
 from aiohttp.test_utils import unused_port
 
@@ -1510,8 +1513,44 @@ async def handler(request):
         assert 200 == resp.status
 
 
-async def test_POST_DATA_DEFLATE(aiohttp_client) -> None:
-    async def handler(request):
+@pytest.mark.parametrize("data", (None, b""))
+async def test_GET_DEFLATE(
+    aiohttp_client: AiohttpClient, data: Optional[bytes]
+) -> None:
+    async def handler(request: web.Request) -> web.Response:
+        return web.json_response({"ok": True})
+
+    write_mock = None
+    original_write_bytes = ClientRequest.write_bytes
+
+    async def write_bytes(
+        self: ClientRequest, writer: StreamWriter, conn: Connection
+    ) -> None:
+        nonlocal write_mock
+        original_write = writer._write
+
+        with mock.patch.object(
+            writer, "_write", autospec=True, spec_set=True, side_effect=original_write
+        ) as write_mock:
+            await original_write_bytes(self, writer, conn)
+
+    with mock.patch.object(ClientRequest, "write_bytes", write_bytes):
+        app = web.Application()
+        app.router.add_get("/", handler)
+        client = await aiohttp_client(app)
+
+        async with client.get("/", data=data, compress=True) as resp:
+            assert resp.status == 200
+            content = await resp.json()
+            assert content == {"ok": True}
+
+    assert write_mock is not None
+    # No chunks should have been sent for an empty body.
+    write_mock.assert_not_called()
+
+
+async def test_POST_DATA_DEFLATE(aiohttp_client: AiohttpClient) -> None:
+    async def handler(request: web.Request) -> web.Response:
         data = await request.post()
         return web.json_response(dict(data))