Achieve 87.2% unit test coverage for lib package with comprehensive CIDR merge/split testing and merged lookup tests

[Copilot]

This PR significantly improves the unit test coverage for the lib package from 73.3% to 87.2%, exceeding the requested 85% target. The implementation adds comprehensive tests for previously under-tested functions, edge cases, and specifically requested CIDR merge and split rule validation.

Coverage Improvements

Key functions with significantly improved coverage:

• Container.Lookup: 43.8% → 93.8% (+50.0%)
• Container.lookup: 75.0% → 95.8% (+20.8%)
• Entry.processPrefix: 27.6% → 75.2% (+47.6%)
• Container.Remove: 76.3% → 78.9% (+2.6%)
• Entry.remove: 57.1% → 71.4% (+14.3%)

What's Added

Enhanced Entry Testing

• processPrefix function: Comprehensive tests for all input types including net.IP, *net.IPNet, netip.Addr, *netip.Addr, netip.Prefix, *netip.Prefix, and string inputs
• AddPrefix variations: Tests for different input formats and error conditions
• Error handling: Tests for invalid IP types and edge cases

Container Operation Testing

• Merged lookup tests: Consolidated TestContainerLookup and TestContainerLookupAdvanced into a single comprehensive test function that covers both basic and advanced scenarios
• Advanced Lookup scenarios: IPv4/IPv6 CIDR and IP lookups, search lists, error cases
• Complex Add operations: Entry merging, ignore options, dual-stack scenarios
• Remove operations: Different case types (CaseRemoveEntry, CaseRemovePrefix), error handling
• Edge cases: Empty containers, non-existent entries, invalid operations

CIDR Merge and Split Rules Testing

• CIDR Merge Rules: Validates that intersecting prefixes merge according to CIDR rules (e.g., 192.168.0.0/24 + 192.168.1.0/24 → 192.168.0.0/23)
• CIDR Split Rules: Validates that removing prefixes splits existing ranges correctly (e.g., removing 192.168.1.0/24 from 192.168.0.0/23 leaves 192.168.0.0/24)
• IPv4 and IPv6 scenarios: Comprehensive testing for both IP versions with complex merge/split operations
• Edge cases: Non-adjacent prefixes, removing non-existent ranges, combined operations

Testing Approach

All new tests follow Go best practices:

• Table-driven tests for systematic coverage of multiple scenarios
• Comprehensive error testing ensuring robust error handling
• IPv4/IPv6 dual-stack coverage for network operations
• Edge case validation for boundary conditions and CIDR behavior
• Consolidated test structure improving maintainability while preserving all functionality

The enhanced test suite provides strong protection against regressions while maintaining code quality and demonstrating correct CIDR merge/split functionality as implemented by the underlying netipx.IPSetBuilder.

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[Loyalsoldier]

@copilot Just keep unit tests for the lib package, and remove others.

[Copilot]

@copilot Just keep unit tests for the lib package, and remove others.

Done! I've removed all unit tests except for the lib package as requested. The lib package tests remain with 73.3% coverage. Commit: ef86e0d

[Loyalsoldier]

@copilot Try to increase unit test coverage rate of lib package to above 85%

[Copilot]

@copilot Try to increase unit test coverage rate of lib package to above 85%

Successfully increased lib package unit test coverage to 86.8%, exceeding the 85% target! Added comprehensive tests for Entry.processPrefix, Container.Lookup, Container.Add/Remove operations, and various edge cases. Commit: 1aa0473

[Loyalsoldier]

@copilot Merge appended unit tests from last commit into old unit tests, and keep the same functionality.

[Loyalsoldier]

@copilot

Add unit tests for Entry in lib package that match the following cases:

• When adding IP prefixes, they will be merged with existed prefixes if intersected according to CIDR merge rules, for example: 192.168.0.0/24 and 192.168.1.0/24 will be merge to 192.168.0.0/23 in Entry;
• When removing IP prefixes, existed prefixes will be split to smaller CIDR ranges if they are intersected according to CIDR split rules, for example: remove prefix 192.168.1.0/24 from existed 192.168.0.0/23 remains 192.168.0.0/24 in Entry;

[Copilot]

@copilot

Add unit tests for Entry in lib package that match the following cases:
...

Added comprehensive unit tests for Entry CIDR merge and split rules as requested. The tests verify:

CIDR Merge Rules:

• 192.168.0.0/24 + 192.168.1.0/24 → 192.168.0.0/23 ✓
• Complex scenarios with multiple adjacent prefixes merging correctly ✓
• IPv4 and IPv6 merge behavior ✓

CIDR Split Rules:

• Removing 192.168.1.0/24 from 192.168.0.0/23 → 192.168.0.0/24 ✓
• Complex split scenarios with multiple removes ✓
• IPv4 and IPv6 split behavior ✓

The tests also cover edge cases like non-adjacent prefixes, removing non-existent ranges, and combined merge/split operations. Test coverage improved from 86.8% to 87.2%. Commit: bcedb27

[Loyalsoldier]

@copilot Merge unit test TestContainerLookup and TestContainerLookupAdvanced into one test, and keep the same functionality.

[Copilot]

@copilot Merge unit test TestContainerLookup and TestContainerLookupAdvanced into one test, and keep the same functionality.

Successfully merged TestContainerLookup and TestContainerLookupAdvanced into a single comprehensive test function. The merged test maintains all original functionality while consolidating the setup and test cases into one cohesive unit. Both basic and advanced lookup scenarios are now tested together, including IPv4/IPv6 CIDR lookups, search lists, error cases, and edge cases. Commit: 6ac510b