Test Coverage Improvement Plan#

Overview#

This document tracks the path to achieving 80% branch coverage across the HashHive backend codebase. The global target is 80% for all metrics (branches, functions, lines, statements), with temporary per-file overrides for areas requiring additional test development.

Current Status (as of 2025-11-19)#

Global Coverage:

• Statements: 83.33% ✅
• Functions: 91.66% ✅
• Lines: 82.75% ✅
• Branches: 53.84% ⚠️

Files Below 80% Branch Coverage#

1. src/config/index.ts (33.33% branches)#

Current Override: 35%
Target: 80%
Uncovered Lines: 61-68

Missing Coverage:

• Environment-specific configuration branches (development vs production)
• Configuration validation error paths
• Optional environment variable handling

Action Items:

• Add unit tests for config module with different NODE_ENV values
• Test missing/invalid environment variable scenarios
• Test default value fallbacks

Timeline: Before adding database/Redis configuration (Task 2.2)

2. src/middleware/error-handler.ts (40% branches)#

Current Override: 45%
Target: 80%
Uncovered Lines: 106-117, 122-132, 136-146

Missing Coverage:

• ZodError formatting and response structure
• AppError with different error codes and status codes
• Generic Error handling paths
• Production vs development error detail exposure

Action Items:

• Expand middleware tests to cover all error types (ZodError, AppError, generic Error)
• Test error responses in both development and production modes
• Verify error logging for each error type
• Test edge cases (errors without messages, errors with circular references)

Timeline: Before Campaign Service implementation (Task 3.3)

3. src/routes/health.ts (50% branches)#

Current Override: 50%
Target: 80%
Uncovered Line: 20

Missing Coverage:

• Likely a conditional branch in one of the health check endpoints
• May involve database/Redis connection checks once implemented

Action Items:

• Review line 20 to identify the uncovered branch
• Add test case for the missing condition
• Once database/Redis are added, test health checks with connection failures

Timeline: Immediate (simple fix) + revisit after database integration (Task 2.2)

Incremental Improvement Strategy#

Phase 1: Foundation (Current Sprint)#

• ✅ Establish 80% global target with per-file overrides
• 🔄 Document coverage gaps and improvement plan
• 🔄 Fix routes/health.ts to reach 80% branches

Phase 2: Core Infrastructure (Before Task 2.2)#

• Improve config/index.ts to 80% branches
• Add comprehensive config validation tests
• Test environment-specific behavior

Phase 3: Error Handling (Before Task 3.3)#

• Improve middleware/error-handler.ts to 80% branches
• Cover all error types and response formats
• Test production vs development error exposure

Phase 4: Ongoing (All Future Tasks)#

• All new code must meet 80% branch coverage
• No new per-file overrides without documented justification
• Remove per-file overrides as coverage improves

Monitoring and Enforcement#

• Coverage reports run on every test execution
• CI/CD pipeline enforces coverage thresholds
• Per-file overrides are temporary and should be removed as tests are added
• Any new per-file override requires:
  1. Update to this document with justification
  2. Action items and timeline
  3. Approval in code review

Notes#

• The src/index.ts file is excluded from coverage as it contains server startup code that's not executed in tests
• Integration tests contribute to coverage but focus on API contract validation
• Unit tests should target specific branches and edge cases