waitFor method

Future<T> waitFor(bool predicate(T state), { Duration timeout = const Duration(seconds: 1), })

Waits for a state that satisfies predicate and returns it.

Checks the current shard.state synchronously; if it already satisfies the predicate, returns it immediately. Otherwise subscribes and returns the first future emission for which predicate(state) is true. Throws ShardTimeoutError if no satisfying state arrives within timeout.

Implementation

Future<T> waitFor(
  bool Function(T state) predicate, {
  Duration timeout = const Duration(seconds: 1),
}) async {
  if (_isDisposed) {
    throw StateError('ShardTester has been disposed');
  }
  if (predicate(_shard.state)) {
    return _shard.state;
  }
  final completer = Completer<T>();
  final wait = _PendingWait<T>(completer, predicate: predicate);
  _waiters.add(wait);
  return completer.future.timeout(
    timeout,
    onTimeout: () {
      _waiters.remove(wait);
      throw ShardTimeoutError(
        'Timed out waiting for matching state after '
        '${timeout.inMilliseconds}ms',
      );
    },
  );
}