[libgpiod][PATCH 9/9] bindings: python: line_request: warn on unknown lines when reconfiguring

[Vincent Fazio <vfazio@gmail.com>]

Previously, attempting to reconfigure a line that was not included in
the original request provided no feedback to the caller that there was
invalid data in the request.

Now, emit a warning when an unknown offset or line name is encountered.

Signed-off-by: Vincent Fazio <vfazio@gmail.com>
---
 bindings/python/gpiod/line_request.py       | 14 ++++++++--
 bindings/python/tests/tests_line_request.py | 29 ++++++++++++++-------
 2 files changed, 31 insertions(+), 12 deletions(-)

diff --git a/bindings/python/gpiod/line_request.py b/bindings/python/gpiod/line_request.py
index 629df3c..deb48a7 100644
--- a/bindings/python/gpiod/line_request.py
+++ b/bindings/python/gpiod/line_request.py
@@ -3,6 +3,7 @@
 
 from __future__ import annotations
 
+import warnings
 from typing import TYPE_CHECKING, Optional, Union, cast
 
 from . import _ext
@@ -173,12 +174,21 @@ class LineRequest:
         for line, settings in config_iter(config):
             try:
                 offset = self._line_to_offset(line)
-                line_settings[offset] = settings
+                if offset in self.offsets:
+                    line_settings[offset] = settings
+                else:
+                    warnings.warn(
+                        f"Line offset '{offset}' was not included in original request.",
+                        stacklevel=2,
+                    )
             except ValueError:
                 # _line_to_offset will raise a ValueError when it encounters
                 # an unrecognized line name. Ignore these like we do offsets
                 # that were not in the original request.
-                pass
+                warnings.warn(
+                    f"Line name '{line}' was not included in original request.",
+                    stacklevel=2,
+                )
 
         for offset in self.offsets:
             settings = line_settings.get(offset) or LineSettings()
diff --git a/bindings/python/tests/tests_line_request.py b/bindings/python/tests/tests_line_request.py
index aa2cd83..8cb0f2c 100644
--- a/bindings/python/tests/tests_line_request.py
+++ b/bindings/python/tests/tests_line_request.py
@@ -1,6 +1,7 @@
 # SPDX-License-Identifier: GPL-2.0-or-later
 # SPDX-FileCopyrightText: 2022 Bartosz Golaszewski <brgl@bgdev.pl>
 
+import warnings
 from unittest import TestCase
 
 import gpiod
@@ -604,22 +605,30 @@ class ReconfigureRequestedLines(TestCase):
     def test_reconfigure_extra_offsets(self) -> None:
         info = self.chip.get_line_info(2)
         self.assertEqual(info.direction, Direction.OUTPUT)
-        self.req.reconfigure_lines(
-            {(0, 2, 3, 6, 5): gpiod.LineSettings(direction=Direction.INPUT)}
-        )
+        with warnings.catch_warnings(record=True) as w:
+            self.req.reconfigure_lines(
+                {(0, 2, 3, 6, 5): gpiod.LineSettings(direction=Direction.INPUT)}
+            )
+            assert len(w) == 1
+            assert issubclass(w[0].category, UserWarning)
+            assert "Line offset '5'" in str(w[0].message)
         info = self.chip.get_line_info(2)
         self.assertEqual(info.direction, Direction.INPUT)
 
     def test_reconfigure_extra_names(self) -> None:
         info = self.chip.get_line_info(2)
         self.assertEqual(info.direction, Direction.OUTPUT)
-        self.req.reconfigure_lines(
-            {
-                (0, 2, "foo", "baz", "buzz"): gpiod.LineSettings(
-                    direction=Direction.INPUT
-                )
-            }
-        )
+        with warnings.catch_warnings(record=True) as w:
+            self.req.reconfigure_lines(
+                {
+                    (0, 2, "foo", "baz", "buzz"): gpiod.LineSettings(
+                        direction=Direction.INPUT
+                    )
+                }
+            )
+            assert len(w) == 1
+            assert issubclass(w[0].category, UserWarning)
+            assert "Line name 'buzz'" in str(w[0].message)
         info = self.chip.get_line_info(2)
         self.assertEqual(info.direction, Direction.INPUT)
 
-- 
2.43.0