Context

Follow-up from PR #315 and this comment.

Description

Add comprehensive automated tests for the new claim_token endpoint and its dependent logic in src/faucet/server_api.rs.

Test Coverage Needed

Unit Tests

• parse_and_validate_address: Test valid and invalid address parsing
  • Invalid address format → assert BAD_REQUEST (400)
  • Valid addresses for different networks

Integration/Endpoint Tests

• Mainnet branch: Request with FaucetInfo::MainnetFIL → assert IM_A_TEAPOT (418) response
• Rate limiting: Trigger rate limit → assert TOO_MANY_REQUESTS (429) response with proper retry-after message
• CalibnetFIL success path: Mock Provider and test native token claim → assert success and valid transaction ID returned
• CalibnetUSDFC success path: Mock Provider and test ERC-20 token claim → assert success and valid transaction ID returned

Implementation Notes

• Mock or stub Provider::from_network and faucet_address for deterministic test execution
• Consider using mockall or test-only implementations for RPC/provider behavior
• Ensure tests assert both HTTP status codes and ServerFnError variants appropriately
• Add focused unit tests for handle_native_claim and handle_erc20_claim

Related

• PR: Calibnet token claim api #315
• Requested by: @sudo-shashank