Re-export parse_address and migrate fork-guard tests to pid-cache patch

Three small cycle-21 follow-ups:

- ``parse_address`` was promoted to public in cycle 21 but never added
  to ``dqliteclient.__init__.py``'s ``__all__``. Cross-package
  consumers still had to reach into ``dqliteclient.connection``,
  re-introducing the cross-package private-API drift the rename was
  meant to close. Re-export it.

- Fork-guard tests across the client and dbapi patched
  ``dqliteclient.connection.os.getpid``, ``dqliteclient.pool.os.getpid``,
  ``dqliteclient.cluster.os.getpid``, ``dqlitedbapi.connection.os.getpid``,
  and ``dqlitedbapi.aio.connection.os.getpid``. Cycle 21 moved every
  hot-path pid check from ``os.getpid()`` to a cached module attribute
  (``dqliteclient.connection._current_pid``) refreshed by
  ``os.register_at_fork``. The patches were dead code — the tests
  passed only because they also mutated ``_creator_pid`` directly.
  Migrate every patch to ``patch("dqliteclient.connection._current_pid", ...)``
  so the test exercises the production read path it claims to.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: antoineleclair

src/dqliteclient/__init__.py

@@ -10,7 +10,7 @@
 """
 
 from dqliteclient.cluster import ClusterClient, RedirectPolicy, allowlist_policy
-from dqliteclient.connection import DqliteConnection
+from dqliteclient.connection import DqliteConnection, parse_address
 from dqliteclient.exceptions import (
     ClusterError,
     ClusterPolicyError,
@@ -48,6 +48,7 @@
     "OperationalError",
     "ProtocolError",
     "RedirectPolicy",
+    "parse_address",
     "__version__",
     "allowlist_policy",
     "connect",

tests/test_cluster_client_fork_guard.py

@@ -29,7 +29,7 @@ async def test_find_leader_after_fork_raises_interface_error() -> None:
     cluster._creator_pid = fake_parent_pid
 
     with (
-        patch("dqliteclient.cluster.os.getpid", return_value=fake_parent_pid + 1),
+        patch("dqliteclient.connection._current_pid", fake_parent_pid + 1),
         pytest.raises(InterfaceError, match="fork"),
     ):
         await cluster.find_leader()

tests/test_connection_after_fork_raises.py

@@ -131,7 +131,7 @@ def test_dqlite_connection_close_after_fork_drops_inherited_state() -> None:
     conn._creator_pid = fake_parent_pid
 
     async def run() -> None:
-        with patch("dqliteclient.connection.os.getpid", return_value=fake_parent_pid + 1):
+        with patch("dqliteclient.connection._current_pid", fake_parent_pid + 1):
             await conn.close()
 
     asyncio.run(run())

tests/test_pool_close_fork_during_parent_close.py

@@ -61,7 +61,7 @@ async def test_close_with_pid_mismatch_returns_even_when_closed_with_pending_eve
 
     # Bound the await so a regression manifests as a clean failure
     # instead of a hung test.
-    with patch("dqliteclient.pool.os.getpid", return_value=fake_parent_pid + 1):
+    with patch("dqliteclient.connection._current_pid", fake_parent_pid + 1):
         await asyncio.wait_for(pool.close(), timeout=1.0)
 
     # Local state flipped, no wait happened.
@@ -80,7 +80,7 @@ async def test_close_with_pid_mismatch_returns_even_when_closed_with_no_event()
     fake_parent_pid = pool._creator_pid + 1
     pool._creator_pid = fake_parent_pid
 
-    with patch("dqliteclient.pool.os.getpid", return_value=fake_parent_pid + 1):
+    with patch("dqliteclient.connection._current_pid", fake_parent_pid + 1):
         await asyncio.wait_for(pool.close(), timeout=1.0)
 
     assert pool._closed is True

tests/test_transaction_fork_diagnostic.py

@@ -40,8 +40,13 @@ async def test_transaction_after_fork_raises_fork_diagnostic_not_cross_task() ->
     fake_parent_pid = conn._creator_pid + 1
     conn._creator_pid = fake_parent_pid
 
+    # Patch the module-level pid cache so the misuse guard observes a
+    # fresh-process pid different from ``_creator_pid``. Cycle 21 moved
+    # the hot-path pid check from ``os.getpid()`` to a cached module
+    # attribute updated via ``os.register_at_fork``; patching
+    # ``os.getpid`` would be dead code.
     with (
-        patch("dqliteclient.connection.os.getpid", return_value=fake_parent_pid + 1),
+        patch("dqliteclient.connection._current_pid", fake_parent_pid + 1),
         pytest.raises(InterfaceError, match="fork") as excinfo,
     ):
         async with conn.transaction():