More verification paths in unit tests

[danielinux]

• Added important verification paths in unit tests
• Added more tests to cover argument checks

[Copilot]

Pull request overview

This PR expands wolfIP’s unit test suite to cover additional verification/guard paths and edge cases across TCP, routing, poll scheduling, and DNS/DHCP handling.

Changes:

• Added targeted TCP option parsing tests (truncation/invalid lengths, mixed options, unknown kinds, SACK block clamping).
• Added tests for poll behavior (draining all expired timers, enforcing poll budget), accept() half-open cloning/SYN-ACK queueing, and several TCP persist/zero-window/RTO guard paths.
• Added DNS/DHCP tests for resend-query argument guards, malformed compressed-name abort behavior, and DHCP renewing/rebinding ACK processing.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
src/test/unit/unit_tests_tcp_flow.c	Adds coverage for tcp_parse_options() edge cases (truncation, mixed options, SACK limits).
src/test/unit/unit_tests_tcp_ack.c	Adds routing mask==0 exact-match case and non-ethernet TTL-exceeded filter behavior test.
src/test/unit/unit_tests_proto.c	Adds tests for TCP persist/zero-window probes/RTO paths and various guard-path helpers.
src/test/unit/unit_tests_dns_dhcp.c	Adds DNS resend failure-mode tests, DHCP renewing/rebinding ACK poll tests, and malformed compressed-name abort coverage.
src/test/unit/unit_tests_api.c	Adds tests for wolfIP_poll() timer draining, poll budget enforcement, filter socket-event defaults, and accept() half-open cloning behavior.
src/test/unit/unit.c	Registers the newly added tests into the suite.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.