[Task]: TEST-005: Test Certificate Generation Logic

[jeromehardaway]

Priority: P0 - Critical
Effort: Medium (4-6 hours)
File: src/lib/certificates.test.ts

Description

Develop comprehensive test suite for certificate generation and validation system. This is mission-critical functionality that directly impacts veteran certifications and must be thoroughly tested to ensure accurate, sequential certificate issuance and proper eligibility verification.

Test Cases

• ✅ generateCertificateNumber() - format VWC-YYYY-XXXXXX
• ✅ generateCertificateNumber() - sequential numbering
• ✅ generateCertificateNumber() - year rollover scenario
• ✅ hasCompletedCourse() - completed, not completed, not enrolled
• ✅ checkCertificateEligibility() - all eligibility criteria
• ✅ checkCertificateEligibility() - course not found
• ✅ checkCertificateEligibility() - duplicate certificate check
• ✅ getCertificateByNumber() - valid/invalid numbers
• ✅ formatCertificateData() - data transformation
• ✅ Mock Prisma queries

Acceptance Criteria

• 100% code coverage for certificates.ts
• Prisma client mocked correctly for all database operations
• Date handling tested properly (timezone-aware, year boundaries)
• Certificate number uniqueness guaranteed
• All eligibility rules validated
• Edge cases covered (concurrent requests, race conditions)
• Tests run in <2 seconds
• No duplicate certificate numbers generated

Technical Notes

• Use jest.mock('@prisma/client') or vitest mocking
• Test certificate number format: VWC-YYYY-XXXXXX where XXXXXX is zero-padded sequential
• Mock Date.now() for consistent year rollover testing
• Verify sequential numbering under concurrent operations
• Test eligibility criteria: course completion, enrollment status, no existing certificate

Data Integrity Considerations

• Ensure certificate numbers are globally unique
• Test transaction rollback scenarios
• Verify no certificates issued to ineligible users
• Test database constraint violations
• Mock realistic course completion data

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