fix: honour the PGCONNECT_TIMEOUT env var

docs/news.rst

@@ -17,6 +17,8 @@ Psycopg 3.1.15 (unreleased)
   :ticket:`#694`).
 - Fix async connection to hosts resolving to multiple IP addresses (regression
   in 3.1.13, :ticket:`#695`).
+- Respect the :envvar:`PGCONNECT_TIMEOUT` environment variable to determine
+  the connection timeout.
 
 
 Current release

psycopg/psycopg/conninfo.py

@@ -446,7 +446,9 @@ def timeout_from_conninfo(params: ConnDict) -> int:
     # - at least 2 seconds.
     #
     # See connectDBComplete in fe-connect.c
-    value = params.get("connect_timeout", _DEFAULT_CONNECT_TIMEOUT)
+    value: str | int | None = _get_param(params, "connect_timeout")
+    if value is None:
+        value = _DEFAULT_CONNECT_TIMEOUT
     try:
         timeout = int(value)
     except ValueError:

tests/test_conninfo.py

@@ -8,6 +8,7 @@
 from psycopg import ProgrammingError
 from psycopg.conninfo import make_conninfo, conninfo_to_dict, ConnectionInfo
 from psycopg.conninfo import conninfo_attempts, conninfo_attempts_async
+from psycopg.conninfo import timeout_from_conninfo, _DEFAULT_CONNECT_TIMEOUT
 from psycopg._encodings import pg2pyenc
 
 from .fix_crdb import crdb_encoding
@@ -530,6 +531,25 @@ async def test_conninfo_random_async(fake_resolve):
     assert hostaddrs != sorted(hostaddrs)
 
 
+@pytest.mark.parametrize(
+    "conninfo, want, env",
+    [
+        ("", _DEFAULT_CONNECT_TIMEOUT, None),
+        ("host=foo", _DEFAULT_CONNECT_TIMEOUT, None),
+        ("connect_timeout=-1", _DEFAULT_CONNECT_TIMEOUT, None),
+        ("connect_timeout=0", _DEFAULT_CONNECT_TIMEOUT, None),
+        ("connect_timeout=1", 2, None),
+        ("connect_timeout=10", 10, None),
+        ("", 15, {"PGCONNECT_TIMEOUT": "15"}),
+    ],
+)
+def test_timeout(setpgenv, conninfo, want, env):
+    setpgenv(env)
+    params = conninfo_to_dict(conninfo)
+    timeout = timeout_from_conninfo(params)
+    assert timeout == want
+
+
 @pytest.fixture
 async def fake_resolve(monkeypatch):
     fake_hosts = {