[JarryShaw]

• Searched for similar pull requests
• Followed the coding style (make pylint, make mypy, make isort)
• make test passes, and a test case covers the change
• Changelog entry: N/A — centralised in docs(changelog): shared 1.5.0 changelog — long-lived, merges last (#610, #616, #617, #618, #620) #657

What is the purpose of your pull request?

• fix — corrects a defect

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Description of your pull request and other information

Field.pack now passes a bytearray to struct.pack as bytes when the format ends in s or p. PyPy refuses a bytearray there with TypeError: expected bytes, got bytearray object, and CPython accepts it. This is the only struct.pack call under corekit/fields/, so BytesField, StringField, the address fields and every wrapper go through it.

memoryview, and a bytearray for c, are left alone: CPython already refuses both, so converting them would accept something new.

test_fields_bytearray_pack_2004_unit.py uses a struct stand-in that refuses a bytearray, as PyPy does. It fails without the fix: 8 SUBFAILED on CPython, 12 on PyPy 8.0.1. The tests/corekit/test_fields_* files and the IPv6 CALIPSO make test pass on both interpreters.

Closes #2004

[JarryShaw]

GOOD TO GO at e1cb15d2c. A Sonnet review checked the conversion:

• Every template under corekit/fields/ is a single-code string, and no field uses p. A multi-code template would end in another letter and be left as is.
• Only a bytearray bound for s/p is converted; memoryview, bool, str, list and a bytearray for c still raise.
• With field.py reverted, the new test fails (8 failed), with the struct stand-in patched where Field.pack reads it.

I ran all 22 tests/corekit/test_fields_* files, which pass. PaddingField.pack, the one override that skips Field.pack, already converts to bytes itself.

[github-actions]

Coverage: 91.54% (unit tier, Python 3.15, e1cb15d2c, Unit Tests run success)

Package	Statements	Missed	Branches	Partial	Cover
pcapkit (top level)	104	4	20	2	95.16%
pcapkit/const	19597	881	2618	867	92.11%
pcapkit/corekit	2542	71	810	37	96.54%
pcapkit/dumpkit	276	3	100	3	98.40%
pcapkit/foundation	2929	23	1020	25	98.78%
pcapkit/interface	138	4	52	3	96.32%
pcapkit/protocols	17468	222	4600	187	98.13%
pcapkit/toolkit	872	36	298	10	95.21%
pcapkit/utilities	523	2	158	4	99.12%
pcapkit/vendor	4431	1995	1018	167	51.73%

Per-file detail: the coverage-html artifact of this run.