test: add a case for upgradetohd with null characters in mnemonic passphrase

[UdjinM6]

Issue being fixed or feature implemented

Null characters aren't allowed in mnemonic passphrases, the first one and everything after it is ignored. This might change after #6792 but let's add a test to make sure it's working like that right now anyway.

What was done?

How Has This Been Tested?

Run test

Breaking Changes

n/a

Checklist:

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have added or updated relevant unit/integration/functional/e2e tests
• I have made corresponding changes to the documentation
• I have assigned this pull request to a milestone (for repository code-owners and collaborators only)

[github-actions]

✅ No Merge Conflicts Detected

This PR currently has no conflicts with other open PRs.

[coderabbitai]

Walkthrough

A new test case has been added to the run_test method in wallet_upgradetohd.py. This test creates a blank wallet, upgrades it to HD using a custom mnemonic and a passphrase containing embedded null characters, and checks that the wallet balance matches the expected value. The test confirms that null characters in the passphrase are ignored from the first occurrence. No other logic, error handling, or public entity declarations were modified.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~7 minutes

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📥 Commits

Reviewing files that changed from the base of the PR and between dc63e25 and e155bd9.

📒 Files selected for processing (1)

• test/functional/wallet_upgradetohd.py (1 hunks)

🧰 Additional context used

📓 Path-based instructions (1)

test/functional/**/*.py

📄 CodeRabbit Inference Engine (CLAUDE.md)

Functional tests should be written in Python and placed in test/functional/

Files:

• test/functional/wallet_upgradetohd.py

🧠 Learnings (3)

📓 Common learnings

Learnt from: kwvg
PR: dashpay/dash#6543
File: src/wallet/receive.cpp:240-251
Timestamp: 2025-02-06T14:34:30.466Z
Learning: Pull request #6543 is focused on move-only changes and refactoring, specifically backporting from Bitcoin. Behavior changes should be proposed in separate PRs.

Learnt from: kwvg
PR: dashpay/dash#6761
File: src/chainlock/signing.cpp:247-250
Timestamp: 2025-07-29T14:32:48.369Z
Learning: In PR #6761, kwvg acknowledged a null pointer check issue in ChainLockSigner::Cleanup() method but deferred it to follow-up, consistent with the pattern of avoiding scope creep in refactoring PRs.

Learnt from: kwvg
PR: dashpay/dash#6718
File: test/functional/test_framework/test_framework.py:2102-2102
Timestamp: 2025-06-09T16:43:20.996Z
Learning: In the test framework consolidation PR (#6718), user kwvg prefers to limit functional changes to those directly related to MasternodeInfo, avoiding scope creep even for minor improvements like error handling consistency.

Learnt from: UdjinM6
PR: dashpay/dash#6786
File: ci/test/04_install.sh:99-101
Timestamp: 2025-08-01T07:46:37.840Z
Learning: In backport PRs like #6786, UdjinM6 prefers to defer non-critical fixes (such as shell command expansion issues) to separate commits/PRs to maintain focus on the primary backport objectives, consistent with the project's pattern of avoiding scope creep.

Learnt from: kwvg
PR: dashpay/dash#6761
File: src/wallet/wallet.cpp:0-0
Timestamp: 2025-07-29T14:33:01.040Z
Learning: In refactoring PRs like #6761, kwvg acknowledges code safety improvements (like null pointer checks and unused parameter warnings) but prefers to defer them to follow-up PRs to maintain focus on the primary refactoring objectives, avoiding scope creep.

Learnt from: kwvg
PR: dashpay/dash#6529
File: src/wallet/rpcwallet.cpp:3002-3003
Timestamp: 2025-02-14T15:19:17.218Z
Learning: The `GetWallet()` function calls in `src/wallet/rpcwallet.cpp` are properly validated with null checks that throw appropriate RPC errors, making additional validation unnecessary.

📚 Learning: the `getwallet()` function calls in `src/wallet/rpcwallet.cpp` are properly validated with null chec...

Learnt from: kwvg
PR: dashpay/dash#6529
File: src/wallet/rpcwallet.cpp:3002-3003
Timestamp: 2025-02-14T15:19:17.218Z
Learning: The `GetWallet()` function calls in `src/wallet/rpcwallet.cpp` are properly validated with null checks that throw appropriate RPC errors, making additional validation unnecessary.

Applied to files:

• test/functional/wallet_upgradetohd.py

📚 Learning: in the test framework consolidation pr (#6718), user kwvg prefers to limit functional changes to tho...

Learnt from: kwvg
PR: dashpay/dash#6718
File: test/functional/test_framework/test_framework.py:2102-2102
Timestamp: 2025-06-09T16:43:20.996Z
Learning: In the test framework consolidation PR (#6718), user kwvg prefers to limit functional changes to those directly related to MasternodeInfo, avoiding scope creep even for minor improvements like error handling consistency.

Applied to files:

• test/functional/wallet_upgradetohd.py

🔇 Additional comments (1)

test/functional/wallet_upgradetohd.py (1)

250-256: LGTM! Well-designed test case for null character handling.

The test effectively validates the current behavior where null characters in mnemonic passphrases are ignored from the first occurrence onward. The implementation follows established patterns in the file and correctly asserts that the wallet balance matches the expected value (12) from the equivalent test without null characters.

The descriptive comment clearly explains the expected behavior, making the test's purpose transparent for future maintainers.

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[UdjinM6]

closing in fav of #6792