test(plugins): add parser unit tests for scapy_recon plugin (#1431)

[Khanvilkarshravani27]

Description

Adds a dedicated parser unit test suite for the scapy_recon plugin to protect parser behaviour from regressions.

The new test file (testing/backend/test_scapy_recon_parser.py) includes 38 tests that cover:

• Metadata contract: Validates metadata.json structure, required fields, engine binary, and output parser type.
• Normal ARP output: Verifies correct IP + MAC extraction, finding keys, category, severity, description, and remediation.
• ICMP output: Verifies hosts with no MAC address default to "Unknown".
• Edge cases: Ensures the parser handles single hosts, empty inputs, whitespace-only, malformed strings, mixed valid/noise lines, and large subnet outputs (50 hosts) without crashing.

Related Issues

Closes #1431

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Testing (Adds missing parser test coverage for an existing plugin)

How Has This Been Tested?

Ran the test suite locally using pytest to ensure all new and existing tests pass:

python -m pytest testing/backend/test_scapy_recon_parser.py -v --noconftest

Checklist

• My code follows the code style of this project.
• I have performed a self-review of my own code.
• I have commented my code, particularly in hard-to-understand areas.
• I have made corresponding changes to the documentation.
• My changes generate no new warnings.

[utksh1]

Some of the scapy_recon parser tests are useful, but this PR is too bloated and mixes in unrelated parser_sandbox changes.\n\n1. Remove the unrelated backend/sandbox changes.\n2. Trim the test suite to the meaningful parser regression cases instead of large volumes of repetitive shape assertions.\n3. Keep the PR focused on the parser behavior only.\n\nPlease resubmit a smaller, more targeted test PR.

[Khanvilkarshravani27]

Hi @utksh1,

Thanks for the feedback — all points are now addressed:

• Removed unrelated parser_sandbox.py changes
• Trimmed redundant shape/volume assertions and duplicate empty‑key check
• Squashed to a single commit (test‑file only, parser behaviour focus)

Let me know if you'd like any further changes.

[utksh1]

The unrelated sandbox code is gone, but this is still much larger than needed for parser regression coverage: it includes a broad metadata contract suite and many redundant shape assertions. Please reduce it to focused parser cases (normal output, empty output, malformed input, noise, and missing MAC), then rebase on current main and rerun CI.

[Khanvilkarshravani27]

Hi @utksh1,

All points addressed:

• Removed the metadata contract suite and redundant shape assertions
• Trimmed to 11 focused tests: normal ARP output, missing MAC, empty input, noise lines, and malformed input (parametrized)
• Rebased on current main and force-pushed as a single clean commit

All 11 tests pass locally:

python -m pytest testing/backend/test_scapy_recon_parser.py -v --noconftest
# 11 passed in 0.52s