anchor.diff:    stdOutLines.listen((line) => printOnFailure('StdOut: $line'));
     stdErrLines.listen((line) => printOnFailure('StdErr: $line'));
   
  -  extraExpects.add(() => nextSuccessfulBuild);
  -  await Future.wait(extraExpects.map((cb) async => await cb()));
  +  await nextSuccessfulBuild;
   }
   
   /// Kills the current build script.
  
positive.code: }
  
  Future<void> _startServer(String command, List<String> buildArgs,
      {bool? ensureCleanBuild, List<Function>? extraExpects}) async {
    ensureCleanBuild ??= false;
    extraExpects ??= [];
  
    // Make sure this is a clean build
    if (ensureCleanBuild && await _toolDir.exists()) {
  
negative.code: /// build to complete.
  ///
  /// To ensure a clean build, set [ensureCleanBuild] to `true`.
  Future<void> startServer({bool? ensureCleanBuild, List<String>? buildArgs}) =>
      _startServer(
        'dart',
        [
          '--packages=.packages',
          p.join('..', 'build_runner', 'bin', 'build_runner.dart'),
          'serve',
          '--verbose',
          if (buildArgs != null) ...buildArgs,
        ],
        ensureCleanBuild: ensureCleanBuild,
      );
  
  Future<ProcessResult> _runBuild(String command, List<String> args,
      {bool? ensureCleanBuild}) async {
  