Low Test Coverage: app/actions/resend/index.ts

[gitauto-ai]

Resolves #596

Summary

Add comprehensive unit tests for app/actions/resend/index.ts to raise line and statement coverage to 100%, covering success, validation, and failure paths with minimal code changes.

Test Patterns

• Happy path: invokes Resend client with a valid payload and returns the expected success result.
• Missing env/API key: throws or returns a meaningful error when required environment configuration is absent.
• Input validation: rejects when required fields (e.g., to, subject, body) are missing or invalid; ensures optional fields are handled correctly (e.g., cc, bcc, replyTo, attachments).
• Upstream/API failure: propagates/normalizes non-2xx API errors from the Resend client.
• Network/runtime error: surfaces transport errors (e.g., request failure/timeout) as expected.
• No-op on invalid input: does not call the Resend client when validation fails.
• Payload integrity: forwards headers/metadata correctly and omits undefined optionals to avoid leaking nullish fields.

git fetch origin
git checkout gitauto/issue-596-20260105-124218-YZOK
git pull origin gitauto/issue-596-20260105-124218-YZOK