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CPF and CNPJ in tests: generate, validate and avoid confusion

CPF/CNPJ generators are useful for software work, but a number valid by check digits does not prove existence, ownership or permission to use it.

Mathematical validation is not official lookup

The check-digit algorithm catches many typing errors, but it does not query official registries. Real data requires an authorized source and legitimate purpose.

Safe use in development

Prefer synthetic data in automated tests, documentation and staging. Never use generated numbers to impersonate real identity or bypass third-party validation.

For tests, synthetic CPF/CNPJ is a technical tool; for real decisions, use official sources and proper legal basis.