Function ensureExpectedIsNonNegativeInteger

packages/jest-matcher-utils/src/index.ts:230–250

(
  expected: unknown,
  matcherName: string,
  options?: MatcherHintOptions,
)

};

export const ensureExpectedIsNonNegativeInteger = (
  expected: unknown,
  matcherName: string,
  options?: MatcherHintOptions,
): void => {
  if (
    typeof expected !== 'number' ||
    !Number.isSafeInteger(expected) ||
    expected < 0
  ) {
    // Prepend maybe not only for backward compatibility.
    const matcherString = (options ? '' : '[.not]') + matcherName;
    throw new Error(
      matcherErrorMessage(
        matcherHint(matcherString, undefined, undefined, options),
        `${EXPECTED_COLOR('expected')} value must be a non-negative integer`,
        printWithType('Expected', expected, printExpected),
      ),
    );
  }
};

// Given array of diffs, return concatenated string:
// * include common substrings