Brazilian CNH Generator

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Synthetic Brazilian driver license number for test fixtures

Synthetic CNH for test fixtures

A CNH fixture needs 11 coherent digits: a 9-digit base and 2 modulo-11 check digits, one dependent on the other. Calling the random generator on every test works, but breaks CI reproducibility; this page shows how to pin the seed, read the deterministic value and handle the filter that discards repeated sequences before they reach your test.

What a CNH fixture needs to know about the generator

The value has exactly 11 numeric digits, no letter, unlike the RG: a 9-digit base followed by 2 check digits, displayed in the format 123 456 789-00, three space-separated blocks of three and a final two-digit block after the dash. Before returning the number, the function checks whether all 11 digits together form a repeated sequence, like 11111111111, and discards that result even when the check-digit math closes out correctly; it tries up to 20 random bases under that condition before falling back to the fixed value 12345678900.
Just like the RG generator, you can inject a custom digit source instead of the default draw: a fixed sequence replayed in the same order always produces the same CNH, which lets you compare the result against a constant in a contract test without relying on luck. For an even more direct case, the function that takes a ready 9-digit base computes the two check digits with no randomness involved, useful when the fixture only needs one fixed value reused across many different test cases.
The detail that most often confuses a contract test is that the second check digit depends on the outcome of the first: if the first calculation exceeds 9, it is reset to 0 and an adjustment of 2 is subtracted from the second calculation before applying the remainder of the division by 11. A test that recalculates both digits independently, without replicating that conditional adjustment, will diverge from the generator exactly in the cases where the first digit would overflow the 0-to-9 range, so it is worth covering that path with a dedicated test case.

Three synthetic CNHs, three generator behaviors

Deterministic seed, common path

Input: createCnhFromBase('123456789')
Expected output: 123 456 789-00

Simple sequential base, easy to remember in a test; both check digits land on 00 without triggering the conditional adjustment.

Base that triggers both digit adjustments

Input: createCnhFromBase('987654321')
Expected output: 987 654 321-09

This base is the rare case where the first calculation exceeds 9 and the second calculation goes negative before adjustment, exercising both special rules at once.

Repeated sequence, always rejected

Input: createCnhFromBase('111111111')
Expected output: 111 111 111-11 (o gerador nunca devolve esse valor via generateCnh)

The calculation mathematically closes on 11111111111, but the repeated-digit filter discards that value before it ever reaches your fixture.

Full tool FAQ

Is the generated CNH a real document?

No. It only follows the mathematical format used by form validators.

Does the tool query an official database?

Why do check digits matter in tests?

Can I use it in staging?

Does CNH include a state code like voter ID?

Is the number stored locally?

Does this replace official validation?

When should I use fixed fixtures?

Frequently asked questions

How do I lock the seed of a synthetic CNH for a test that runs in CI?

Inject your own digit function in place of the default random source, always returning the same sequence, or call the function that takes the 9-digit base directly; any test comparing against a fixed value should use one of these two paths, never the generator with raw randomness.

Why does my contract test compute a different second check digit than the generator?

Probably because the test recalculates both digits independently, without replicating the conditional adjustment that resets the first digit and subtracts 2 from the second when the first calculation's raw result exceeds 9; that adjustment only shows up for a fraction of possible bases, so the bug hides in most test cases.

Can the generator return a synthetic CNH with all 11 digits repeated?

No: even when the check-digit calculation mathematically closes on a sequence like 11111111111, a separate filter rejects any result where all 11 digits are identical, retrying up to 20 times before falling back to the fixed value.

Does a synthetic CNH generated here correspond to any real license?

No, the number only reproduces the 11-digit format and the two-check-digit modulo-11 calculation; it does not query any driving record, license category, point balance or suspension status.

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Synthetic Brazilian driver license number for test fixtures

Synthetic CNH for test fixtures

What a CNH fixture needs to know about the generator

The value has exactly 11 numeric digits, no letter, unlike the RG: a 9-digit base followed by 2 check digits, displayed in the format 123 456 789-00, three space-separated blocks of three and a final two-digit block after the dash. Before returning the number, the function checks whether all 11 digits together form a repeated sequence, like 11111111111, and discards that result even when the check-digit math closes out correctly; it tries up to 20 random bases under that condition before falling back to the fixed value 12345678900.

Just like the RG generator, you can inject a custom digit source instead of the default draw: a fixed sequence replayed in the same order always produces the same CNH, which lets you compare the result against a constant in a contract test without relying on luck. For an even more direct case, the function that takes a ready 9-digit base computes the two check digits with no randomness involved, useful when the fixture only needs one fixed value reused across many different test cases.

The detail that most often confuses a contract test is that the second check digit depends on the outcome of the first: if the first calculation exceeds 9, it is reset to 0 and an adjustment of 2 is subtracted from the second calculation before applying the remainder of the division by 11. A test that recalculates both digits independently, without replicating that conditional adjustment, will diverge from the generator exactly in the cases where the first digit would overflow the 0-to-9 range, so it is worth covering that path with a dedicated test case.

Three synthetic CNHs, three generator behaviors

Deterministic seed, common path

Input: createCnhFromBase('123456789')
Expected output: 123 456 789-00

Simple sequential base, easy to remember in a test; both check digits land on 00 without triggering the conditional adjustment.

Base that triggers both digit adjustments

Input: createCnhFromBase('987654321')
Expected output: 987 654 321-09

This base is the rare case where the first calculation exceeds 9 and the second calculation goes negative before adjustment, exercising both special rules at once.

Repeated sequence, always rejected

Input: createCnhFromBase('111111111')
Expected output: 111 111 111-11 (o gerador nunca devolve esse valor via generateCnh)

The calculation mathematically closes on 11111111111, but the repeated-digit filter discards that value before it ever reaches your fixture.

Full tool FAQ

Is the generated CNH a real document?

No. It only follows the mathematical format used by form validators.

Does the tool query an official database?

Why do check digits matter in tests?

Can I use it in staging?

Does CNH include a state code like voter ID?

Is the number stored locally?

Does this replace official validation?

When should I use fixed fixtures?

Frequently asked questions

How do I lock the seed of a synthetic CNH for a test that runs in CI?

Why does my contract test compute a different second check digit than the generator?

Can the generator return a synthetic CNH with all 11 digits repeated?

Does a synthetic CNH generated here correspond to any real license?

No, the number only reproduces the 11-digit format and the two-check-digit modulo-11 calculation; it does not query any driving record, license category, point balance or suspension status.