Function createErrDiff

lib/internal/assert/assertion_error.js:185–236

(actual, expected, operator, customMessage, diffType = 'simple')

}

function createErrDiff(actual, expected, operator, customMessage, diffType = 'simple') {
  operator = checkOperator(actual, expected, operator);

  let skipped = false;
  let message = '';
  const inspectedActual = inspectValue(actual);
  const inspectedExpected = inspectValue(expected);
  const inspectedSplitActual = StringPrototypeSplit(inspectedActual, '\n');
  const inspectedSplitExpected = StringPrototypeSplit(inspectedExpected, '\n');
  const showSimpleDiff = isSimpleDiff(actual, inspectedSplitActual, expected, inspectedSplitExpected);
  let header = `${colors.green}+ actual${colors.white} ${colors.red}- expected${colors.white}`;

  if (showSimpleDiff) {
    const simpleDiff = getSimpleDiff(actual, inspectedSplitActual[0], expected, inspectedSplitExpected[0]);
    message = simpleDiff.message;
    if (typeof simpleDiff.header !== 'undefined') {
      header = simpleDiff.header;
    }
    if (simpleDiff.skipped) {
      skipped = true;
    }
  } else if (inspectedActual === inspectedExpected) {
    // Handles the case where the objects are structurally the same but different references
    operator = 'notIdentical';
    if (inspectedSplitActual.length > 50 && diffType !== 'full') {
      message = `${ArrayPrototypeJoin(ArrayPrototypeSlice(inspectedSplitActual, 0, 50), '\n')}\n...}`;
      skipped = true;
    } else {
      message = ArrayPrototypeJoin(inspectedSplitActual, '\n');
    }
    header = '';
  } else {
    const checkCommaDisparity = actual != null && typeof actual === 'object';
    const diff = myersDiff(inspectedSplitActual, inspectedSplitExpected, checkCommaDisparity);

    const myersDiffMessage = printMyersDiff(diff, operator);
    message = myersDiffMessage.message;

    if (operator === 'partialDeepStrictEqual') {
      header = `${colors.gray}${colors.hasColors ? '' : '+ '}actual${colors.white} ${colors.red}- expected${colors.white}`;
    }

    if (myersDiffMessage.skipped) {
      skipped = true;
    }
  }

  const headerMessage = `${getErrorMessage(operator, customMessage)}\n${header}`;
  const skippedMessage = skipped ? '\n... Skipped lines' : '';

  return `${headerMessage}${skippedMessage}\n${message}\n`;
}

function addEllipsis(string) {
  const lines = StringPrototypeSplit(string, '\n', 11);