From 0415a4ca18e15e734999925fd7f20607f05e2a4b Mon Sep 17 00:00:00 2001
From: Alexey Nikitin <30608416+NewGlad@users.noreply.github.com>
Date: Tue, 16 Apr 2024 23:36:07 +0800
Subject: [PATCH] 
 Patchback/backports/3.9/5fd29467fb63efdfae1ace280cec36b1f8139567/pr 8290
 (#8311)

---
 CHANGES/8253.bugfix          |  1 +
 CONTRIBUTORS.txt             |  1 +
 aiohttp/client.py            | 73 +++++++++++++++++++-----------------
 tests/test_client_session.py | 10 +++++
 4 files changed, 50 insertions(+), 35 deletions(-)
 create mode 100644 CHANGES/8253.bugfix

diff --git a/CHANGES/8253.bugfix b/CHANGES/8253.bugfix
new file mode 100644
index 00000000000..91b06d9b35d
--- /dev/null
+++ b/CHANGES/8253.bugfix
@@ -0,0 +1 @@
+Fixed "Unclosed client session" when initialization of ClientSession fails -- by :user:`NewGlad`.
diff --git a/CONTRIBUTORS.txt b/CONTRIBUTORS.txt
index ab889685fc8..277171a239e 100644
--- a/CONTRIBUTORS.txt
+++ b/CONTRIBUTORS.txt
@@ -27,6 +27,7 @@ Alexander Shorin
 Alexander Travov
 Alexandru Mihai
 Alexey Firsov
+Alexey Nikitin
 Alexey Popravka
 Alexey Stepanov
 Amin Etesamian
diff --git a/aiohttp/client.py b/aiohttp/client.py
index 7e9b32fad6f..32d2c3b7119 100644
--- a/aiohttp/client.py
+++ b/aiohttp/client.py
@@ -234,6 +234,44 @@ def __init__(
         max_field_size: int = 8190,
         fallback_charset_resolver: _CharsetResolver = lambda r, b: "utf-8",
     ) -> None:
+        # We initialise _connector to None immediately, as it's referenced in __del__()
+        # and could cause issues if an exception occurs during initialisation.
+        self._connector: Optional[BaseConnector] = None
+        if timeout is sentinel or timeout is None:
+            self._timeout = DEFAULT_TIMEOUT
+            if read_timeout is not sentinel:
+                warnings.warn(
+                    "read_timeout is deprecated, " "use timeout argument instead",
+                    DeprecationWarning,
+                    stacklevel=2,
+                )
+                self._timeout = attr.evolve(self._timeout, total=read_timeout)
+            if conn_timeout is not None:
+                self._timeout = attr.evolve(self._timeout, connect=conn_timeout)
+                warnings.warn(
+                    "conn_timeout is deprecated, " "use timeout argument instead",
+                    DeprecationWarning,
+                    stacklevel=2,
+                )
+        else:
+            if not isinstance(timeout, ClientTimeout):
+                raise ValueError(
+                    f"timeout parameter cannot be of {type(timeout)} type, "
+                    "please use 'timeout=ClientTimeout(...)'",
+                )
+            self._timeout = timeout
+            if read_timeout is not sentinel:
+                raise ValueError(
+                    "read_timeout and timeout parameters "
+                    "conflict, please setup "
+                    "timeout.read"
+                )
+            if conn_timeout is not None:
+                raise ValueError(
+                    "conn_timeout and timeout parameters "
+                    "conflict, please setup "
+                    "timeout.connect"
+                )
         if loop is None:
             if connector is not None:
                 loop = connector._loop
@@ -271,41 +309,6 @@ def __init__(
         self._default_auth = auth
         self._version = version
         self._json_serialize = json_serialize
-        if timeout is sentinel or timeout is None:
-            self._timeout = DEFAULT_TIMEOUT
-            if read_timeout is not sentinel:
-                warnings.warn(
-                    "read_timeout is deprecated, " "use timeout argument instead",
-                    DeprecationWarning,
-                    stacklevel=2,
-                )
-                self._timeout = attr.evolve(self._timeout, total=read_timeout)
-            if conn_timeout is not None:
-                self._timeout = attr.evolve(self._timeout, connect=conn_timeout)
-                warnings.warn(
-                    "conn_timeout is deprecated, " "use timeout argument instead",
-                    DeprecationWarning,
-                    stacklevel=2,
-                )
-        else:
-            if not isinstance(timeout, ClientTimeout):
-                raise ValueError(
-                    f"timeout parameter cannot be of {type(timeout)} type, "
-                    "please use 'timeout=ClientTimeout(...)'",
-                )
-            self._timeout = timeout
-            if read_timeout is not sentinel:
-                raise ValueError(
-                    "read_timeout and timeout parameters "
-                    "conflict, please setup "
-                    "timeout.read"
-                )
-            if conn_timeout is not None:
-                raise ValueError(
-                    "conn_timeout and timeout parameters "
-                    "conflict, please setup "
-                    "timeout.connect"
-                )
         self._raise_for_status = raise_for_status
         self._auto_decompress = auto_decompress
         self._trust_env = trust_env
diff --git a/tests/test_client_session.py b/tests/test_client_session.py
index a0654ed8ccd..416b6bbce5d 100644
--- a/tests/test_client_session.py
+++ b/tests/test_client_session.py
@@ -885,3 +885,13 @@ async def test_build_url_returns_expected_url(
 ) -> None:
     session = await create_session(base_url)
     assert session._build_url(url) == expected_url
+
+
+async def test_instantiation_with_invalid_timeout_value(loop):
+    loop.set_debug(False)
+    logs = []
+    loop.set_exception_handler(lambda loop, ctx: logs.append(ctx))
+    with pytest.raises(ValueError, match="timeout parameter cannot be .*"):
+        ClientSession(timeout=1)
+    # should not have "Unclosed client session" warning
+    assert not logs