code: function assertMatch(actual, expected, message) {
    if (isRegExp(expected))
      assert(expected.test(actual), message || `Expected "${actual}" to match "${expected}"`);
    else if (typeof expected === 'function')
      assert(expected(actual), message);
    else
      assert.deepEqual(actual, expected, message);
  }
docs: Used to assert that actual matches expected value, where expected may be a function or a string.