[FEATURE]: Add Basic Unit Tests for Transaction Signing and Verification

[dhruvi-16-me]

Feature and its Use Cases

📄 Description

MiniChain plans to implement transaction signing and verification using PyNaCl.

Once the core transaction logic is available, it would be beneficial to add a minimal unit test suite to ensure correctness and prevent subtle cryptographic bugs.

Since MiniChain aims to be a clean and educational blockchain implementation, including simple tests would improve reliability without adding unnecessary complexity.

Proposed Test Cases

1. Valid Transaction

   • A properly signed transaction should verify successfully.

2. Modified Transaction Data

   • Changing transaction fields (e.g., amount) after signing should cause verification to fail.

3. Invalid Public Key

   • Using an incorrect public key should fail verification.

4. Replay Protection

   • Reusing a transaction with the same nonce should be rejected by state validation logic.

Suggested Approach

• Use Python’s built-in unittest or pytest
• Add a tests/ directory
• Keep test coverage minimal but focused on correctness

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Why This Matters

• Ensures deterministic and correct signature verification
• Prevents subtle security issues
• Encourages test-driven development
• Keeps the project aligned with its educational goal

Additional Context

No response

Code of Conduct

• I have joined the Discord server and will post updates there
• I have searched existing issues to avoid duplicates

[shrilakshmikakati]

I would like to contribute to this issue by adding a minimal test suite to validate transaction signing and verification implemented with PyNaCl. The tests will ensure that a correctly signed transaction verifies successfully, while any modification to transaction data or use of an incorrect public key causes verification to fail.

The test suite will include the following cases:

1. Valid Transaction: Ensure a properly signed transaction verifies successfully.
2. Modified Transaction Data: Changing fields such as amount after signing should invalidate the signature.
3. Invalid Public Key: Verification should fail when using a different public key.
4. Replay Protection: Transactions with the same nonce should be rejected by the state validation logic.

I will implement these tests using pytest in a dedicated tests/ directory to keep the testing structure simple and maintainable. The goal is to improve reliability and catch potential cryptographic errors while keeping MiniChain aligned with its educational and minimal design.