[TECH DEBT] Test Coverage

[humanauction]

Test Coverage Improvements

Summary

Current test coverage is 16% with several critical production files having 0% coverage. This document tracks necessary test additions and fixes to reach target coverage of 60-70%.

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Critical Issues (0% Coverage)

1. NetMonDaemon.cpp (358 lines, 0% covered) 🔴 HIGH PRIORITY

Problem: No integration tests exist for the HTTP daemon that serves metrics endpoints.

Required Tests:

• Test daemon starts successfully on specified port
• Test /api/metrics endpoint returns valid JSON
• Test /api/flows endpoint returns flow data
• Test /api/sessions endpoint with authentication
• Test graceful shutdown on SIGTERM/SIGINT
• Test concurrent request handling
• Test error responses (404, 500, etc.)
• Test CORS headers if applicable

Implementation:

// filepath: tests/integration/test_netmon_daemon.cpp
- Start daemon in background thread
- Make HTTP requests using httplib
- Verify responses and status codes
- Clean shutdown after tests

Estimated Coverage Gain: +215 lines (~60% of file)

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2. PcapAdapter.cpp (86 lines, 0% covered) 🔴 HIGH PRIORITY

Problem: test_pcap_adapter.cpp exists (47 lines) but produces no coverage data. Test is likely failing silently or not running.

Investigation Needed:

• Check if test segfaults when run directly: ./build/test_runner
• Verify test is built and linked in CMakeLists.txt
• Check if test requires root/sudo (pcap needs privileges)
• Review test expectations vs actual PcapAdapter behavior

Required Tests:

• Test opening pcap file (offline mode)
• Test opening network interface with proper error handling
• Test setting pcap filter expressions
• Test packet callback mechanism
• Test statistics retrieval (packets captured/dropped)
• Mock pcap calls for CI environment (no sudo)
• Test graceful handling of missing interfaces

Implementation:

// filepath: tests/unit/test_pcap_adapter.cpp
- Use GTEST_SKIP() if not running as root
- Test with sample.pcap file instead of live interface
- Mock pcap_* functions for unit testing
- Add privilege check before interface tests

Estimated Coverage Gain: +60 lines (~70% of file)

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3. StatsPersistence.cpp (78 lines, 0% covered) 🟡 MEDIUM PRIORITY

Problem: No tests for SQLite database operations (save/load stats).

Required Tests:

• Test saveStats() writes to database successfully
• Test loadStats() retrieves saved stats correctly
• Test database schema creation
• Test handling of corrupt database files
• Test concurrent access (if applicable)
• Test in-memory database for fast testing
• Test migration between schema versions
• Test cleanup of old data

Implementation:

// filepath: tests/unit/test_stats_persistence.cpp
- Use `:memory:` SQLite database for tests
- Create sample AggregatedStats with known values
- Verify round-trip save/load preserves data
- Test error conditions (disk full, permissions, etc.)

Estimated Coverage Gain: +62 lines (~80% of file)

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4. main.cpp (58 lines, 0% covered) 🟢 LOW PRIORITY

Problem: CLI entry point has no functional tests.

Required Tests:

• Test --help flag displays usage
• Test --version flag displays version
• Test invalid argument handling
• Test signal handling (SIGINT, SIGTERM)
• Test daemon mode vs foreground mode
• Test configuration file loading
• Test interface selection (-i eth0)
• Test filter expression parsing

Implementation:

// filepath: tests/integration/test_main.cpp
- Use system() to invoke ./netnet binary
- Capture stdout/stderr
- Verify exit codes
- Test argument combinations

Estimated Coverage Gain: +17 lines (~30% of file)

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Medium Priority Issues

5. test_pcap_adapter.cpp (47 lines, 0% covered)

Problem: Test file itself has no coverage, indicating it's not running.

Action Items:

• Verify test is registered with gtest
• Check CMakeLists.txt for proper test executable definition
• Run test manually and capture output/errors
• Add to CI test runner if missing
• Fix any segfaults or assertion failures

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6. Parser.cpp (49 lines, 59% covered)

Problem: Missing edge case coverage.

Additional Tests Needed:

• Test IPv6 packet parsing
• Test fragmented packets
• Test VLAN-tagged packets
• Test malformed headers (fuzz testing)
• Test non-TCP/UDP protocols (ICMP, etc.)
• Test jumbo frames
• Test zero-length payloads

Estimated Coverage Gain: +20 lines (→ 100%)

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7. ConnectionTracker.cpp (59 lines, 79% covered)

Problem: Missing coverage for edge cases.

Additional Tests Needed:

• Test flow expiration/cleanup
• Test bidirectional flow tracking
• Test flow state transitions (SYN, FIN, RST)
• Test maximum flow table size limits
• Test flow serialization/deserialization

Estimated Coverage Gain: +12 lines (→ 100%)

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8. StatsAggregator.cpp (56 lines, 92% covered)

Problem: Near-complete but missing edge cases.

Additional Tests Needed:

• Test window advancement with no packets
• Test history overflow (circular buffer wraparound)
• Test concurrent access (if multithreaded)
• Test stats reset/clear

Estimated Coverage Gain: +4 lines (→ 100%)

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Testing Infrastructure Improvements

CI/CD Pipeline

• Add coverage threshold check (fail if below 60%)
• Generate HTML coverage reports as artifacts
• Add branch coverage metrics (not just line coverage)
• Set up nightly full test runs with valgrind
• Add performance regression tests

Test Fixtures

• Create diverse sample.pcap files for testing
  • Small packets (< 64 bytes)
  • Large packets (jumbo frames)
  • IPv4 and IPv6 traffic
  • TCP handshakes, UDP streams, ICMP
  • Malformed/corrupted packets
• Add test database fixtures
• Create mock HTTP responses for daemon tests

Test Organization

• Split unit tests from integration tests
• Add smoke tests for quick validation
• Add end-to-end tests (full pipeline)
• Document test naming conventions
• Add test data generators for large-scale tests

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Excluded from Coverage (Vendor Code)

The following files are intentionally excluded from coverage metrics:

• include/net-net/vendor/httplib.h (2175 lines) - Third-party HTTP library
• include/net-net/vendor/bcrypt.cpp (45 lines) - Third-party crypto library
• include/net-net/vendor/uuid_gen.cpp - UUID generation utility

Total vendor lines: ~2220 (should not count toward coverage goals)

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Coverage Goals

Metric	Current	Target	Stretch Goal
Overall Coverage	16%	60%	70%
src/ Coverage	25%	70%	85%
Critical Files (NetMonDaemon, PcapAdapter)	0%	60%	80%
Unit Test Coverage	~86%	90%	95%

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Estimated Timeline

Phase 1: Critical Fixes (Week 1)

• Fix test_pcap_adapter (not running)
• Add basic test_netmon_daemon (HTTP endpoint smoke tests)
• Expected gain: 16% → 25%

Phase 2: Core Coverage (Week 2)

• Complete NetMonDaemon integration tests
• Add StatsPersistence unit tests
• Expand Parser edge case tests
• Expected gain: 25% → 45%

Phase 3: Comprehensive Testing (Week 3)

• Add main.cpp functional tests
• Add end-to-end integration tests
• Performance and stress tests
• Expected gain: 45% → 60%

Phase 4: Polish (Week 4)

• Reach for 70% coverage
• Add fuzz testing
• Valgrind clean runs
• Documentation updates
• Expected gain: 60% → 70%

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Related Issues

• #TODO: Document test execution requirements (sudo for pcap)
• #TODO: Set up code coverage dashboard (Codecov integration)
• #TODO: Add pre-commit hook for running tests
• #TODO: Create developer guide for writing tests

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Notes

• Current test suite takes ~6 seconds to run (mostly SessionManager sleep tests)
• Consider mocking time in SessionManager tests to speed up CI
• PcapAdapter tests may need elevated privileges in CI
• NetMonDaemon tests need to bind to ephemeral ports to avoid conflicts

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Last Updated: December 8, 2025
Owner: @guns4kids
Priority: High - Blocking production readiness