Add report_revenue duplicate-rejection tests asserting rev_rej event and zero state change

[thlpkee20-wq]

Description

When report_revenue is called for an existing period_id with override_existing=false, it emits rev_rej and returns Ok(()) with no state mutation. There is no explicit assertion that AuditSummary.total_revenue, report_count, and the stored period amount are all unchanged after rejection. Add a test locking this no-op guarantee.

Requirements and context

• Must be secure, tested, and documented
• Should be efficient and easy to review
• Relevant code: src/lib.rs (report_revenue rejected branch, get_audit_summary, get_revenue_by_period), src/test_duplicates.rs
• Assert the rev_rej event carries (attempted_amount, period_id, existing_amount)

Suggested execution

• Fork the repo and create a branch
• git checkout -b feat/report-revenue-duplicate-tests
• Implement changes
  • Report a period, capture AuditSummary
  • Re-report same period with a different amount and override_existing=false
  • Assert AuditSummary and stored amount unchanged and rev_rej emitted
• Validate security and correctness assumptions

Test and commit

• Run tests
  • cargo test
• Cover edge cases
  • Duplicate with identical amount, larger amount, smaller amount
• Include test output and security notes

Example commit message

test: assert duplicate report_revenue is a no-op with rev_rej

Guidelines

• Minimum 95 percent test coverage
• Clear documentation
• Timeframe: 96 hours