Function isAsymmetricMatcher

api/vitest.utils.test.ts:38–44

(x: unknown)

describe('serializeDates', () => {
  function isAsymmetricMatcher(x: unknown): x is typeof expect.any {
    return (
      typeof x === 'object' &&
      x !== null &&
      typeof (x as { asymmetricMatch?: unknown }).asymmetricMatch === 'function'
    );
  }

  test('returns primitives unchanged', () => {
    expect(serializeDates(42)).toBe(42);