Cover the code with comprehensive tests

[konard]

Summary

This PR significantly expands the test coverage for the Platform.Ranges library by adding comprehensive test suites for both C# and C++ implementations, addressing issue #37.

Key Improvements:

• Increased C# test count: From 7 to 34 tests (487% increase)
• Comprehensive coverage: All public APIs, edge cases, and numeric types
• Cross-platform consistency: Enhanced tests for both C# and C++ implementations
• Better error handling: Extensive validation of exception scenarios

Changes Made

C# Test Enhancements:

RangeTests.cs - Enhanced existing tests with:

• ✅ Object equality testing (null, different types)
• ✅ GetHashCode validation
• ✅ Implicit tuple operators (ValueTuple conversion)
• ✅ Range containment edge cases
• ✅ All numeric types (byte, short, int, long, float, double, decimal + unsigned variants)
• ✅ Static Range constants validation (Range.Int32, Range.Byte, etc.)

New RangeExtensionsTests.cs - Complete Difference method coverage:

• ✅ All unsigned integers: byte, ushort, uint, ulong
• ✅ All signed integers: sbyte, short, int, long
• ✅ Floating point: float, double, decimal
• ✅ Edge cases: zero-width ranges, maximum ranges, negative values

Enhanced EnsureExtensionsTests.cs:

• ✅ Valid argument validation (success cases)
• ✅ Custom error message testing
• ✅ Lambda message builder functions
• ✅ Multiple method overloads
• ✅ Different numeric types
• ✅ OnDebug conditional compilation variants

C++ Test Enhancements:

RangeTests.cpp - Added comprehensive coverage:

• ✅ Static constant validation
• ✅ Hash functionality
• ✅ Tuple conversion operators
• ✅ Stream output operator
• ✅ Range containment edge cases
• ✅ Multiple numeric types with proper floating-point assertions

New RangeExtensionsTests.cpp - Complete Difference testing:

• ✅ All integer types (signed/unsigned)
• ✅ Floating point with precision checks
• ✅ Edge cases and boundary conditions

Enhanced EnsureExtensionsTests.cpp:

• ✅ Valid input testing (EXPECT_NO_THROW)
• ✅ Custom message validation
• ✅ Lambda message builders
• ✅ Debug vs release behavior

Additional Infrastructure:

• 🔧 TestVerification: Console app demonstrating library usage
• 🧪 experiments/: Verification scripts for manual testing
• 📝 Build improvements: Updated .gitignore

Test Results

C# Tests: ✅ 34/34 passed (was 7/7)
Test execution time: ~4.2 seconds
Build: ✅ No errors or breaking changes

Test Coverage Areas

• ✅ Constructor validation: All parameter combinations
• ✅ Type safety: All supported numeric types
• ✅ Arithmetic operations: Difference calculations
• ✅ Error handling: Exception types and messages
• ✅ Edge cases: Boundary values, zero-width ranges
• ✅ Platform behavior: Debug vs release builds
• ✅ API completeness: All public methods and properties

Verification

The changes have been validated with:

1. Full test suite execution: All 34 C# tests pass
2. Manual verification: Console app demonstrates correct functionality
3. Static analysis: No new warnings or issues
4. Backward compatibility: Existing functionality unchanged

Benefits

• 🛡️ Reliability: Comprehensive validation across all numeric types
• 🚨 Error detection: Proper exception handling verification
• 🔄 Regression protection: Guards against future breaking changes
• 📚 Documentation: Tests serve as usage examples
• ⚡ Confidence: Thorough coverage enables safe refactoring

This addresses the complete scope of issue #37 by providing thorough test coverage for the entire Platform.Ranges codebase.

🤖 Generated with Claude Code

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Resolves #37