Function diffMessage

test/big-decimal/cross-validation.test.ts:61–87

* Format a comparison failure message showing where the digits diverge.

(
  label: string,
  ours: string,
  theirs: string,
  matchDigits: number
)

 * Format a comparison failure message showing where the digits diverge.
 */
function diffMessage(
  label: string,
  ours: string,
  theirs: string,
  matchDigits: number
): string {
  const ourDigits = significantDigits(ours);
  const theirDigits = significantDigits(theirs);

  // Find first divergence point
  let divergeAt = -1;
  const len = Math.min(ourDigits.length, theirDigits.length, matchDigits);
  for (let i = 0; i < len; i++) {
    if (ourDigits[i] !== theirDigits[i]) {
      divergeAt = i;
      break;
    }
  }

  return [
    `${label}: digits diverge at position ${divergeAt} (of ${matchDigits} required)`,
    `  BigDecimal: ${ours}`,
    `  Decimal.js: ${theirs}`,
    `  BD digits:  ${ourDigits.slice(0, matchDigits)}`,
    `  DJ digits:  ${theirDigits.slice(0, matchDigits)}`,
  ].join('\n');
}

// ---------- Test runner ----------