✅ given Uuid class when calling v4 then should return valid UUID v4 string
✅ given Uuid class when calling v4 multiple times then should return unique UUIDs
✅ given Uuid class when instantiated then should throw error
✅ given v4 function when called then should return valid UUID v4 string
✅ given v4 function when called multiple times then should return unique UUIDs
✅ given v4 function when called then should return UUID with correct format (8-4-4-4-12)
✅ given generated UUID when checking version then should have version 4 identifier
✅ given generated UUID when checking variant then should have correct variant bits
✅ given 1000 generated UUIDs when checking version and variant then should all be compliant
✅ given generated UUIDs when checking format then should match RFC 4122 pattern
✅ given 100 UUIDs when generated then should all be unique
✅ given 10000 UUIDs when generated then should all be unique
✅ given generated UUIDs when analyzing character distribution then should have good entropy
✅ given crypto available when generating UUID then should use crypto.getRandomValues
✅ given crypto not available when generating UUID then should use Math.random fallback
✅ given crypto not available when generating multiple UUIDs then should warn only once
✅ given Math.random fallback when generating UUIDs then should still produce unique results
✅ given valid UUID v4 strings when validating then should pass validation
✅ given invalid UUID strings when validating then should fail validation
✅ given UUID strings in different cases when validating then should pass validation regardless of case
✅ given non-string values when validating then should fail validation
✅ given high volume generation when generating 1000 UUIDs then should complete quickly and all be unique
✅ given continuous generation when generating 10000 UUIDs then should maintain performance
✅ given repeated calls when generating many UUIDs then should not cause memory leaks