utils: parse microsecond-precise ISO 8601 and Apache offsets, keep --start-time/--end-time comparable

[HrachShah]

Summary

parse_timestamp in log_analyzer_cli/utils.py could not parse several common timestamp shapes that the regex it tries already captures:

• ISO 8601 with microseconds and a timezone offset (2025-10-10T13:55:36.123456+00:00)
• ISO 8601 with microseconds and Z (2025-10-10T13:55:36.123456Z)
• ISO 8601 with a space separator, microseconds, and an offset (2025-10-10 13:55:36.123456+00:00)

It also lost the offset on Apache common log timestamps: the regex captured 10/Oct/2025:13:55:36 only, dropping the trailing ±HHMM entirely.

Changes

• src/log_analyzer_cli/utils.py:
  • _try_parse_datetime now orders formats from most specific to least specific, so a T%H:%M:%S.%f%z shape is tried before a plain T%H:%M:%S%z (and before T%H:%M:%S.%f without a timezone). Added the previously missing T%H:%M:%S.%f%z, H:%M:%S.%f%z, T%H:%M:%S %z, and Apache's %d/%b/%Y:%H:%M:%S %z formats.
  • The Apache timestamp regex now optionally captures the ±HHMM offset, and the new %d/%b/%Y:%H:%M:%S %z format preserves it on the returned datetime.
• src/log_analyzer_cli/cli.py: _parse_file now strips a tz-aware tzinfo from the parsed timestamp before comparing it against a naive --start-time/--end-time bound, so the bounds can filter a log whose entries carry a UTC offset without raising TypeError: can't compare offset-naive and offset-aware datetimes.
• tests/test_utils.py: 26 new tests covering microsecond-precise ISO shapes (with and without timezone, with and without Z, with positive and negative offsets), the space-separator form, Apache common log with and without offset, RFC 3164 syslog, naive inputs, and a regression that asserts fractional seconds and the timezone offset round-trip.

Test results

python3 -m pytest tests/ → 73 passed (47 pre-existing + 26 new).

Summary by Sourcery

Extend timestamp parsing and comparison to handle timezone-aware and microsecond-precise log entries while keeping CLI time range filters robust.

New Features:

• Support parsing ISO 8601 timestamps with microseconds and timezone offsets, including Z and space-separated variants.
• Support parsing Apache common log timestamps with optional numeric timezone offsets.

Enhancements:

• Order datetime parsing formats from most specific to least specific to avoid losing fractional seconds or timezone information.
• Normalize timezone-aware timestamps to naive when applying --start-time/--end-time filters to prevent comparison errors.

Tests:

• Add comprehensive tests covering microsecond-precise ISO 8601 timestamps, Apache common log formats with and without offsets, syslog-style timestamps, and regression cases for preserving fractional seconds and timezone offsets.

[sourcery-ai]

Reviewer's Guide

Enhances timestamp parsing to support microsecond-precise ISO 8601 and Apache log offsets, and makes CLI time-bound filtering robust when comparing offset-aware log entries against naive start/end times, backed by targeted tests.

Sequence diagram for CLI timestamp parsing and naive bounds comparison

sequenceDiagram
    actor User
    participant CLI as _parse_file
    participant Utils as parse_timestamp
    participant Dt as datetime

    User->>CLI: _parse_file(file_path, start_time, end_time)
    loop for each line
        CLI->>Utils: parse_timestamp(line)
        Utils-->>CLI: timestamp
        alt start_time or end_time is set
            alt timestamp.tzinfo is not None
                CLI->>Dt: timestamp.replace(tzinfo=None)
                Dt-->>CLI: compare_ts (naive)
            else timestamp.tzinfo is None
                CLI->>CLI: compare_ts = timestamp
            end
            alt compare_ts < start_time
                CLI->>CLI: continue (skip line)
            else compare_ts > end_time
                CLI->>CLI: continue (skip line)
            end
        end
        CLI->>CLI: parser.parse(line)
    end
    CLI-->>User: parsed results

Loading

File-Level Changes

Change	Details	Files
Broaden and refine timestamp detection and parsing to support microseconds and timezone offsets without losing precision or tzinfo.	Extend ISO 8601 regex to cover optional fractional seconds and timezone offsets including Z and ±HHMM with optional colon. Update Apache common log regex to optionally capture a trailing numeric offset while still matching entries without an offset. Reorder datetime format attempts from most specific to least specific so microsecond+timezone formats are tried before coarser ones that would drop tzinfo or microseconds. Add explicit datetime formats for ISO 8601 with microseconds and timezone (T and space separator), ISO 8601 with timezone but no fractional seconds, Apache common log with optional timezone, and keep existing formats for syslog and naive timestamps.	src/log_analyzer_cli/utils.py
Normalize parsed timestamps before applying CLI start/end-time filters to avoid naive vs aware datetime comparison errors.	Introduce a compare_ts variable that strips tzinfo from offset-aware timestamps while leaving naive timestamps unchanged. Use compare_ts for comparisons against start_time and end_time bounds to prevent TypeError and keep filtering semantics consistent.	src/log_analyzer_cli/cli.py
Add regression tests to cover new timestamp parsing capabilities and ensure fractional seconds and timezone offsets round-trip correctly.	Create a new test module dedicated to utils, especially parse_timestamp behavior. Add tests for ISO 8601 timestamps with microseconds and various timezone representations (Z, +00:00, ±HHMM, negative offsets) and with/without space separator. Add tests for Apache common log timestamps with and without offsets, RFC 3164-style syslog entries, lines without timestamps, and preservation of microseconds and timezone offsets. Include sanity tests for existing helpers detect_log_level and normalize_error_pattern to guard against regressions.	tests/test_utils.py

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⚙️ Run configuration

Configuration used: defaults

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Run ID: 85f94330-df0a-45e3-85d9-90426bd50a6f

📥 Commits

Reviewing files that changed from the base of the PR and between e93757f and 79893e6.

📒 Files selected for processing (3)

• src/log_analyzer_cli/cli.py
• src/log_analyzer_cli/utils.py
• tests/test_utils.py

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/parse-timestamp-microseconds-with-tz

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