fix: add missing days (d) unit to parse_duration (fixes #1)

[iprasen]

Resolves #1

Root Cause

In duration_utils.py, _UNITS defined mappings for weeks (w), hours (h), minutes (m), and seconds (s), but omitted days (d). Because d was included in the regex pattern _TOKEN_RE, durations containing d parsed tokens without raising an error, but silently evaluated the day component as 0 seconds.

Changes

1. duration_utils.py:
   • Added "d": 86400 to _UNITS.
   • Added parse_duration("1d") -> 86400 example to the docstring.
2. tests/test_duration_utils.py:
   • Added test_days validating "1d", "1D" (case-insensitivity), and "2d".
   • Added test_days_combined validating combined durations "2d4h" and "1w2d3h4m5s".

Verification

Ran test suite:

python3 -m unittest discover -v -s tests

Output:

test_combined (test_duration_utils.ParseDuration.test_combined) ... ok
test_days (test_duration_utils.ParseDuration.test_days) ... ok
test_empty_raises (test_duration_utils.ParseDuration.test_empty_raises) ... ok
test_hours (test_duration_utils.ParseDuration.test_hours) ... ok
test_invalid_raises (test_duration_utils.ParseDuration.test_invalid_raises) ... ok
test_minutes (test_duration_utils.ParseDuration.test_minutes) ... ok
test_seconds (test_duration_utils.ParseDuration.test_seconds) ... ok
test_weeks (test_duration_utils.ParseDuration.test_weeks) ... ok

----------------------------------------------------------------------
Ran 8 tests in 0.002s

OK