Properly pickle of Timeout objects + test cases (#203)

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Bernát Gábor <bgabor8@bloomberg.net>

docs/changelog.rst

@@ -1,16 +1,20 @@
 Changelog
 =========
+v3.10.1 (2023-03-22)
+--------------------
+- Handle pickle for :class:`filelock.Timeout` :pr:`203` - by :user:`TheMatt2`.
+
 v3.10.0 (2023-03-15)
--------------------
-- Add support for explicit file modes for lockfiles :pr:`192 - by :user:`jahrules`.
+--------------------
+- Add support for explicit file modes for lockfiles :pr:`192` - by :user:`jahrules`.
 
 v3.9.1 (2023-03-14)
 -------------------
 - Use ``time.perf_counter`` instead of ``time.monotonic`` for calculating timeouts.
 
 v3.9.0 (2022-12-28)
 -------------------
-- Move build backend to ``hatchling`` :pr:`185 - by :user:`gaborbernat`.
+- Move build backend to ``hatchling`` :pr:`185` - by :user:`gaborbernat`.
 
 v3.8.1 (2022-12-04)
 -------------------

pyproject.toml

@@ -71,6 +71,7 @@ line-length = 120
 [tool.isort]
 profile = "black"
 known_first_party = ["filelock"]
+add_imports = ["from __future__ import annotations"]
 
 [tool.mypy]
 python_version = "3.11"

src/filelock/_error.py

@@ -1,15 +1,28 @@
 from __future__ import annotations
 
+from typing import Any
+
 
 class Timeout(TimeoutError):
     """Raised when the lock could not be acquired in *timeout* seconds."""
 
     def __init__(self, lock_file: str) -> None:
-        #: The path of the file lock.
-        self.lock_file = lock_file
+        super().__init__()
+        self._lock_file = lock_file
+
+    def __reduce__(self) -> str | tuple[Any, ...]:
+        return self.__class__, (self._lock_file,)  # Properly pickle the exception
 
     def __str__(self) -> str:
-        return f"The file lock '{self.lock_file}' could not be acquired."
+        return f"The file lock '{self._lock_file}' could not be acquired."
+
+    def __repr__(self) -> str:
+        return f"{self.__class__.__name__}({self.lock_file!r})"
+
+    @property
+    def lock_file(self) -> str:
+        """:return: The path of the file lock."""
+        return self._lock_file
 
 
 __all__ = [

tests/test_error.py

@@ -0,0 +1,30 @@
+from __future__ import annotations
+
+import pickle
+
+from filelock import Timeout
+
+
+def test_timeout_str() -> None:
+    timeout = Timeout("/path/to/lock")
+    assert str(timeout) == "The file lock '/path/to/lock' could not be acquired."
+
+
+def test_timeout_repr() -> None:
+    timeout = Timeout("/path/to/lock")
+    assert repr(timeout) == "Timeout('/path/to/lock')"
+
+
+def test_timeout_lock_file() -> None:
+    timeout = Timeout("/path/to/lock")
+    assert timeout.lock_file == "/path/to/lock"
+
+
+def test_timeout_pickle() -> None:
+    timeout = Timeout("/path/to/lock")
+    timeout_loaded = pickle.loads(pickle.dumps(timeout))
+
+    assert timeout.__class__ == timeout_loaded.__class__
+    assert str(timeout) == str(timeout_loaded)
+    assert repr(timeout) == repr(timeout_loaded)
+    assert timeout.lock_file == timeout_loaded.lock_file