test: cover MNHF validation rejections

[thepastaclaw]

MNHF validation rejection coverage

Summary

• Add unit coverage for malformed MNHF special transactions and missing or
  invalid quorum validation paths.
• Add functional coverage for MNHF mempool rejection and duplicate-MNHF block
  rejection.
• Keep the checks scoped to validation behavior without changing production
  logic.

Validation

• python3 -m py_compile test/functional/feature_mnehf.py
• git diff --check upstream/develop..HEAD
• Code review gate against upstream/develop: Recommendation: ship.
• Not run: C++ unit/functional test execution locally; this worktree does not
  have a built build/src/test/test_dash binary available.

[github-actions]

✅ No Merge Conflicts Detected

This PR currently has no conflicts with other open PRs.

[thepastaclaw]

@coderabbitai review

[coderabbitai]

✅ Actions performed

Review triggered.

Note: CodeRabbit is an incremental review system and does not re-review already reviewed commits. This command is applicable only when automatic reviews are paused.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Repository UI

Review profile: CHILL

Plan: Pro

Run ID: 2f1433e6-9ebd-4f1d-a7ed-a64039d94a72

📥 Commits

Reviewing files that changed from the base of the PR and between beca567 and fd5b45b.

📒 Files selected for processing (2)

• src/test/evo_mnhf_tests.cpp
• test/functional/feature_mnehf.py

---

Walkthrough

This PR extends MNHF (Masternode Hard Fork) test coverage across both unit and functional test suites. The C++ unit tests are enhanced with a parametric payload version override in the CreateMNHFTx builder, enabling new test cases that validate version-bit boundary enforcement and invalid transaction scenarios. The Python functional tests introduce new helper methods for asserting mempool rejection and block submission failures, and add scenarios that test invalid MNEHF signatures and duplicate transaction detection. Both changes focus on validating MNHF verification logic without modifying production code.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and concisely summarizes the main objective: adding test coverage for MNHF validation rejection scenarios.
Description check	✅ Passed	The description is directly related to the changeset, explaining the test additions for MNHF validation rejections in both unit and functional tests.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands and usage tips.}

[thepastaclaw]

Code Review

I reviewed the exact checked-out head fd5b45bc67632009626c59a58f2a9853e2f74454 against upstream/develop, focusing on the new MNHF unit and functional coverage and the corresponding validation paths in src/evo/mnhftx.cpp. The added tests align with the current rejection reasons for malformed payloads, invalid signatures, missing quorums, and duplicate active-chain signals, and I did not find a concrete correctness or Dash-specific integration issue in this patch.

Reviewed commit: fd5b45b