jestjs/jest · error · Error

Unexpected numerical input

Error message

Unexpected numerical input

What it means

Thrown by stringToBytes when the numeric input is a number less than or equal to 0 and not exactly 0. The accepted branches are: 0 (returns 0), (0,1] (percentage), and >1 (absolute bytes). Any negative number, or values like NaN after parsing that slip past the typeof check, hit the final else.

Solutions

1. Use a non-negative value for the memory limit
2. Validate input >= 0 before calling stringToBytes
3. If computing dynamically, clamp with Math.max(0, value)

Example fix

// before
stringToBytes('-512mb');

// after
stringToBytes('512mb');

function assertNonNegativeBytes(input: string | number): void {
  const num = typeof input === 'number' ? input : parseFloat(input);
  if (num < 0) {
    throw new Error('Memory limit must be non-negative');
  }
}

function isNonNegativeMemoryValue(value: string | number): boolean {
  const num = typeof value === 'number' ? value : parseFloat(value);
  return !Number.isNaN(num) && num >= 0;
}

When it happens

Trigger: Passing a negative memory value such as '-512mb' or -100; a percentage like '-10%'; or a numeric input that resolves to a negative number after unit parsing.

Common situations: Sign errors in computed memory limits; user typos adding a stray '-' before a unit; off-by-one arithmetic that produces a negative cap.

Related errors

• For a percentage based memory limit a percentageReference…
• Unexpected input
• Can't find a root directory while resolving a config file…
• "cwd" must be an absolute path. cwd
• Jest: ' ' is not a valid TypeScript configuration loader.

AI-assisted analysis of jestjs/jest@8e6d128e4a (2026-08-10). Data as JSON: /api/errors/992251e883c116e3. Report an issue: GitHub.

Appendix: source

Thrown at packages/jest-config/src/stringToBytes.ts:84

      input = Number.parseFloat(input);
    }
  }

  if (typeof input === 'number') {
    if (input === 0) {
      return 0;
    } else if (input <= 1 && input > 0) {
      if (percentageReference) {
        return Math.floor(input * percentageReference);
      } else {
        throw new Error(
          'For a percentage based memory limit a percentageReference must be supplied',
        );
      }
    } else if (input > 1) {
      return Math.floor(input);
    } else {
      throw new Error('Unexpected numerical input');
    }
  }

  throw new Error('Unexpected input');
}

// https://github.com/import-js/eslint-plugin-import/issues/1590
export default stringToBytes;

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