Function matcherHint

packages/jest-matcher-utils/src/index.ts:524–587

(
  matcherName: string,
  received = 'received',
  expected = 'expected',
  options: MatcherHintOptions = {},
)

// New format: rejects/resolves, not, and matcher name have black color
// Old format: matcher name has dim color
export const matcherHint = (
  matcherName: string,
  received = 'received',
  expected = 'expected',
  options: MatcherHintOptions = {},
): string => {
  const {
    comment = '',
    expectedColor = EXPECTED_COLOR,
    isDirectExpectCall = false, // seems redundant with received === ''
    isNot = false,
    promise = '',
    receivedColor = RECEIVED_COLOR,
    secondArgument = '',
    secondArgumentColor = EXPECTED_COLOR,
  } = options;
  let hint = '';
  let dimString = 'expect'; // concatenate adjacent dim substrings

  if (!isDirectExpectCall && received !== '') {
    hint += DIM_COLOR(`${dimString}(`) + receivedColor(received);
    dimString = ')';
  }

  if (promise !== '') {
    hint += DIM_COLOR(`${dimString}.`) + promise;
    dimString = '';
  }

  if (isNot) {
    hint += `${DIM_COLOR(`${dimString}.`)}not`;
    dimString = '';
  }

  if (matcherName.includes('.')) {
    // Old format: for backward compatibility,
    // especially without promise or isNot options
    dimString += matcherName;
  } else {
    // New format: omit period from matcherName arg
    hint += DIM_COLOR(`${dimString}.`) + matcherName;
    dimString = '';
  }

  if (expected === '') {
    dimString += '()';
  } else {
    hint += DIM_COLOR(`${dimString}(`) + expectedColor(expected);
    if (secondArgument) {
      hint += DIM_COLOR(', ') + secondArgumentColor(secondArgument);
    }
    dimString = ')';
  }

  if (comment !== '') {
    dimString += ` // ${comment}`;
  }