comprehensive edge case testing

Write comprehensive tests that cover edge cases and platform-specific scenarios to uncover underlying implementation issues rather than masking them with workarounds. When encountering failures, investigate the root cause through targeted testing before implementing fallback mechanisms.

For platform-specific issues, add integration tests that run on the affected platforms:

// Instead of adding fallbacks like:
if (!IsReadableFile(*result)) {
  // fallback logic
}

// Add platform-specific integration tests to investigate the root cause

For complex functionality, test edge cases systematically:

// Test comprehensive scenarios like:
// * UTF-16 strings with non-ASCII BMP characters
// * UTF-16 strings with surrogate pairs  
// * Latin1-hack strings with invalid UTF-8
// * Unpaired surrogates in various positions

This approach often reveals bugs in existing implementations that would otherwise remain hidden. As noted in one review: “This was both a nightmare and super helpful as the previous implementation had a number of bugs.” Comprehensive testing serves as both quality assurance and debugging tool, helping teams understand the true behavior of their code rather than working around symptoms.