Add timezone argument to ASCReader and ASCWriter

can/io/asc.py

@@ -9,14 +9,16 @@
 import logging
 import re
 from collections.abc import Generator
-from datetime import datetime
+from datetime import datetime, timezone, tzinfo
 from typing import Any, Final, TextIO
 
 from ..message import Message
 from ..typechecking import StringPathLike
 from ..util import channel2int, dlc2len, len2dlc
 from .generic import TextIOMessageReader, TextIOMessageWriter
 
+_LOCAL_TZ: Final = datetime.now(timezone.utc).astimezone().tzinfo
+
 CAN_MSG_EXT = 0x80000000
 CAN_ID_MASK = 0x1FFFFFFF
 BASE_HEX = 16
@@ -44,24 +46,31 @@ def __init__(
         file: StringPathLike | TextIO,
         base: str = "hex",
         relative_timestamp: bool = True,
+        tz: tzinfo | None = _LOCAL_TZ,
         **kwargs: Any,
     ) -> None:
         """
-        :param file: a path-like object or as file-like object to read from
-                     If this is a file-like object, is has to opened in text
-                     read mode, not binary read mode.
-        :param base: Select the base(hex or dec) of id and data.
-                     If the header of the asc file contains base information,
-                     this value will be overwritten. Default "hex".
-        :param relative_timestamp: Select whether the timestamps are
-                     `relative` (starting at 0.0) or `absolute` (starting at
-                     the system time). Default `True = relative`.
+        :param file:
+            a path-like object or a file-like object to read from.
+            If this is a file-like object, it must be opened in text
+            read mode, not binary read mode.
+        :param base:
+            Select the base ('hex' or 'dec') for CAN IDs and data bytes.
+            If the header of the ASC file contains base information,
+            this value will be overwritten. Default is "hex".
+        :param relative_timestamp:
+            Select whether the timestamps are
+            `relative` (starting at 0.0) or `absolute` (starting at
+            the system time). Default is `True` (relative).
+        :param tz:
+            Timezone for absolute timestamps. Defaults to local timezone.
         """
         super().__init__(file, mode="r")
 
         if not self.file:
             raise ValueError("The given file cannot be None")
         self.base = base
+        self._timezone = tz
         self._converted_base = self._check_base(base)
         self.relative_timestamp = relative_timestamp
         self.date: str | None = None
@@ -93,7 +102,7 @@ def _extract_header(self) -> None:
                 self.start_time = (
                     0.0
                     if self.relative_timestamp
-                    else self._datetime_to_timestamp(self.date)
+                    else self._datetime_to_timestamp(self.date, self._timezone)
                 )
                 continue
 
@@ -115,7 +124,7 @@ def _extract_header(self) -> None:
             break
 
     @staticmethod
-    def _datetime_to_timestamp(datetime_string: str) -> float:
+    def _datetime_to_timestamp(datetime_string: str, tz: tzinfo | None) -> float:
         month_map = {
             "jan": 1,
             "feb": 2,
@@ -155,7 +164,11 @@ def _datetime_to_timestamp(datetime_string: str) -> float:
 
         for format_str in datetime_formats:
             try:
-                return datetime.strptime(datetime_string, format_str).timestamp()
+                return (
+                    datetime.strptime(datetime_string, format_str)
+                    .replace(tzinfo=tz)
+                    .timestamp()
+                )
             except ValueError:
                 continue
 
@@ -279,7 +292,7 @@ def __iter__(self) -> Generator[Message, None, None]:
                 self.start_time = (
                     0.0
                     if self.relative_timestamp
-                    else self._datetime_to_timestamp(datetime_str)
+                    else self._datetime_to_timestamp(datetime_str, self._timezone)
                 )
                 continue
 
@@ -358,14 +371,19 @@ def __init__(
         self,
         file: StringPathLike | TextIO,
         channel: int = 1,
+        tz: tzinfo | None = _LOCAL_TZ,
         **kwargs: Any,
     ) -> None:
         """
-        :param file: a path-like object or as file-like object to write to
-                     If this is a file-like object, is has to opened in text
-                     write mode, not binary write mode.
-        :param channel: a default channel to use when the message does not
-                        have a channel set
+        :param file:
+            a path-like object or a file-like object to write to.
+            If this is a file-like object, it must be opened in text
+            write mode, not binary write mode.
+        :param channel:
+            a default channel to use when the message does not
+            have a channel set. Default is 1.
+        :param tz:
+            Timezone for timestamps in the log file. Defaults to local timezone.
         """
         if kwargs.get("append", False):
             raise ValueError(
@@ -374,10 +392,11 @@ def __init__(
             )
         super().__init__(file, mode="w")
 
+        self._timezone = tz
         self.channel = channel
 
         # write start of file header
-        start_time = self._format_header_datetime(datetime.now())
+        start_time = self._format_header_datetime(datetime.now(tz=self._timezone))
         self.file.write(f"date {start_time}\n")
         self.file.write("base hex  timestamps absolute\n")
         self.file.write("internal events logged\n")
@@ -417,7 +436,7 @@ def log_event(self, message: str, timestamp: float | None = None) -> None:
         if not self.header_written:
             self.started = self.last_timestamp = timestamp or 0.0
 
-            start_time = datetime.fromtimestamp(self.last_timestamp)
+            start_time = datetime.fromtimestamp(self.last_timestamp, tz=self._timezone)
             formatted_date = self._format_header_datetime(start_time)
 
             self.file.write(f"Begin Triggerblock {formatted_date}\n")

doc/changelog.d/2035.added.md

@@ -0,0 +1 @@
+Add new timezone parameter `tz` to `can.io.asc.ASCReader` and `can.io.asc.ASCWriter`.

test/logformats_test.py

@@ -18,15 +18,16 @@
 import unittest
 from abc import ABCMeta, abstractmethod
 from contextlib import contextmanager
-from datetime import datetime
+from datetime import datetime, timedelta, timezone
 from itertools import zip_longest
 from pathlib import Path
 from unittest.mock import patch
 
 from parameterized import parameterized
 
-import can
-from can.io import blf
+import can.io
+from can.io import asc, blf
+
 from .data.example_data import (
     TEST_COMMENTS,
     TEST_MESSAGES_BASE,
@@ -427,9 +428,11 @@ def _read_log_file(self, filename, **kwargs):
 
     def test_read_absolute_time(self):
         time_from_file = "Sat Sep 30 10:06:13.191 PM 2017"
-        start_time = datetime.strptime(
-            time_from_file, self.FORMAT_START_OF_FILE_DATE
-        ).timestamp()
+        start_time = (
+            datetime.strptime(time_from_file, self.FORMAT_START_OF_FILE_DATE)
+            .replace(tzinfo=asc._LOCAL_TZ)
+            .timestamp()
+        )
 
         expected_messages = [
             can.Message(
@@ -629,51 +632,55 @@ def test_read_error_frame_channel(self):
             os.unlink(temp_file.name)
 
     def test_write_millisecond_handling(self):
+        tz = asc._LOCAL_TZ
         now = datetime(
-            year=2017, month=9, day=30, hour=15, minute=6, second=13, microsecond=191456
+            year=2017,
+            month=9,
+            day=30,
+            hour=15,
+            minute=6,
+            second=13,
+            microsecond=191456,
+            tzinfo=tz,
         )
 
-        # We temporarily set the locale to C to ensure test reproducibility
-        with override_locale(category=locale.LC_TIME, locale_str="C"):
-            # We mock datetime.now during ASCWriter __init__ for reproducibility
-            # Unfortunately, now() is a readonly attribute, so we mock datetime
-            with patch("can.io.asc.datetime") as mock_datetime:
-                mock_datetime.now.return_value = now
-                writer = can.ASCWriter(self.test_file_name)
-
-            msg = can.Message(
-                timestamp=now.timestamp(), arbitration_id=0x123, data=b"h"
-            )
-            writer.on_message_received(msg)
+        with patch("can.io.asc.datetime") as mock_datetime:
+            mock_datetime.now.return_value = now
+            writer = can.ASCWriter(self.test_file_name, tz=tz)
 
-            writer.stop()
+        msg = can.Message(timestamp=now.timestamp(), arbitration_id=0x123, data=b"h")
+        writer.on_message_received(msg)
+        writer.stop()
 
         actual_file = Path(self.test_file_name)
         expected_file = self._get_logfile_location("single_frame_us_locale.asc")
 
         self.assertEqual(expected_file.read_text(), actual_file.read_text())
 
     def test_write(self):
-        now = datetime(
-            year=2017, month=9, day=30, hour=15, minute=6, second=13, microsecond=191456
-        )
-
-        # We temporarily set the locale to C to ensure test reproducibility
-        with override_locale(category=locale.LC_TIME, locale_str="C"):
-            # We mock datetime.now during ASCWriter __init__ for reproducibility
-            # Unfortunately, now() is a readonly attribute, so we mock datetime
-            with patch("can.io.asc.datetime") as mock_datetime:
-                mock_datetime.now.return_value = now
-                writer = can.ASCWriter(self.test_file_name)
-
-            msg = can.Message(
-                timestamp=now.timestamp(),
-                arbitration_id=0x123,
-                data=range(64),
+        tz = asc._LOCAL_TZ
+        with patch("can.io.asc.datetime") as mock_datetime:
+            now = datetime(
+                year=2017,
+                month=9,
+                day=30,
+                hour=15,
+                minute=6,
+                second=13,
+                microsecond=191456,
+                tzinfo=tz,
             )
+            mock_datetime.now.return_value = now
+            writer = can.ASCWriter(self.test_file_name, tz=tz)
 
-            with writer:
-                writer.on_message_received(msg)
+        msg = can.Message(
+            timestamp=now.timestamp(),
+            arbitration_id=0x123,
+            data=range(64),
+        )
+
+        with writer:
+            writer.on_message_received(msg)
 
         actual_file = Path(self.test_file_name)
         expected_file = self._get_logfile_location("single_frame.asc")
@@ -684,34 +691,48 @@ def test_write(self):
         [
             (
                 "May 27 04:09:35.000 pm 2014",
-                datetime(2014, 5, 27, 16, 9, 35, 0).timestamp(),
+                datetime(
+                    2014, 5, 27, 16, 9, 35, 0, tzinfo=timezone(timedelta(hours=5))
+                ).timestamp(),
             ),
             (
                 "Mai 27 04:09:35.000 pm 2014",
-                datetime(2014, 5, 27, 16, 9, 35, 0).timestamp(),
+                datetime(
+                    2014, 5, 27, 16, 9, 35, 0, tzinfo=timezone(timedelta(hours=5))
+                ).timestamp(),
             ),
             (
                 "Apr 28 10:44:52.480 2022",
-                datetime(2022, 4, 28, 10, 44, 52, 480000).timestamp(),
+                datetime(
+                    2022, 4, 28, 10, 44, 52, 480000, tzinfo=timezone(timedelta(hours=5))
+                ).timestamp(),
             ),
             (
                 "Sep 30 15:06:13.191 2017",
-                datetime(2017, 9, 30, 15, 6, 13, 191000).timestamp(),
+                datetime(
+                    2017, 9, 30, 15, 6, 13, 191000, tzinfo=timezone(timedelta(hours=5))
+                ).timestamp(),
             ),
             (
                 "Sep 30 15:06:13.191 pm 2017",
-                datetime(2017, 9, 30, 15, 6, 13, 191000).timestamp(),
+                datetime(
+                    2017, 9, 30, 15, 6, 13, 191000, tzinfo=timezone(timedelta(hours=5))
+                ).timestamp(),
             ),
             (
                 "Sep 30 15:06:13.191 am 2017",
-                datetime(2017, 9, 30, 15, 6, 13, 191000).timestamp(),
+                datetime(
+                    2017, 9, 30, 15, 6, 13, 191000, tzinfo=timezone(timedelta(hours=5))
+                ).timestamp(),
             ),
         ]
     )
     def test_datetime_to_timestamp(
         self, datetime_string: str, expected_timestamp: float
     ):
-        timestamp = can.ASCReader._datetime_to_timestamp(datetime_string)
+        timestamp = can.ASCReader._datetime_to_timestamp(
+            datetime_string, tz=timezone(timedelta(hours=5))
+        )
         self.assertAlmostEqual(timestamp, expected_timestamp)