test: comprehensive tests for StellarService and PathPaymentService (Stellar RPC integration)

[KingFRANKHOOD]

Problem

StellarService and PathPaymentService call Stellar RPC but have no test coverage, risking network call failures at runtime.

Scope

Add tests for StellarService:

• getAccountBalance(): fetches USDC balance for valid address, handles account not found (returns 0), handles network timeouts gracefully
• Keypair validation: only valid Ed25519 keys accepted
• Network error handling: retry logic (if implemented), fallback behavior

Add tests for PathPaymentService:

• getPathPaymentQuote(): given source amount/asset, returns valid path payment quotes
• Multi-hop paths: correctly identifies optimal conversion path (NGN → intermediary → USDC)
• Error handling: no path exists (illiquid pair), network timeouts
• Response parsing: quote amount extracted correctly

Add tests for WalletService:

• getUsdcBalance(): delegates to StellarService, correct asset code passed

Acceptance Criteria

• Mock Stellar SDK RpcServer for integration tests
• Test happy path: valid address returns balance
• Test error paths: invalid address (not found on ledger), malformed address (invalid base32)
• Test network errors: timeout, 503 Service Unavailable, connection refused
• Test edge cases: zero balance, extremely large balance (>1B USDC)
• Verify RPC calls are rate-limited appropriately

Estimated Effort

Medium (2-3 half-days)

[midenotch]

@midenotch has applied to work on this issue as part of the Stellar Wave Program's 3rd wave.

Can i work on this

ℹ️ Repo Maintainers: To accept this application, review their application or assign @midenotch to this issue.

[drips-wave]

Congratulations, @midenotch! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on March 30, 2026.

🧑‍💻 @midenotch: Please resolve the issue such that the repo's maintainers have enough time to review your contribution before the due date. You'll earn Points for completing the issue on-time, which will make you eligible for a share of the Stellar Wave Program's reward pool.

Warning

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