Function diff

packages/jest-diff/src/index.ts:63–115

(a: any, b: any, options?: DiffOptions)

// with green and red. (similar to how github does code diffing)
// eslint-disable-next-line @typescript-eslint/explicit-module-boundary-types
export function diff(a: any, b: any, options?: DiffOptions): string | null {
  if (Object.is(a, b)) {
    return getCommonMessage(NO_DIFF_MESSAGE, options);
  }

  const aType = getType(a);
  let expectedType = aType;
  let omitDifference = false;
  if (aType === 'object' && typeof a.asymmetricMatch === 'function') {
    if (a.$$typeof !== Symbol.for('jest.asymmetricMatcher')) {
      // Do not know expected type of user-defined asymmetric matcher.
      return null;
    }
    if (typeof a.getExpectedType !== 'function') {
      // For example, expect.anything() matches either null or undefined
      return null;
    }
    expectedType = a.getExpectedType();
    // Primitive types boolean and number omit difference below.
    // For example, omit difference for expect.stringMatching(regexp)
    omitDifference = expectedType === 'string';
  }

  if (expectedType !== getType(b)) {
    return (
      '  Comparing two different types of values.' +
      ` Expected ${chalk.green(expectedType)} but ` +
      `received ${chalk.red(getType(b))}.`
    );
  }

  if (omitDifference) {
    return null;
  }

  switch (aType) {
    case 'string':
      return diffLinesUnified(
        escapeControlCharacters(a).split('\n'),
        escapeControlCharacters(b).split('\n'),
        options,
      );
    case 'boolean':
    case 'number':
      return comparePrimitive(a, b, options);
    case 'map':
      return compareObjects(sortMap(a), sortMap(b), options);
    case 'set':
      return compareObjects(sortSet(a), sortSet(b), options);
    default:
      return compareObjects(a, b, options);
  }
}

function comparePrimitive(
  a: number | boolean,