anchor.diff:        return true;
       }
   
  -    final int exitCode = await processRunner.runAndStream(
  -      'flutter',
  -      <String>['pub', 'publish', '--', '--dry-run'],
  -      workingDir: package,
  -    );
  -
  -    if (exitCode == 0) {
  +    if (await hasValidPublishCheckRun(package)) {
         print("Package $packageName is able to be published.");
         return true;
       } else {
  
positive.code: // found in the LICENSE file.
  
  import 'dart:async';
  
  import 'package:colorize/colorize.dart';
  import 'package:file/file.dart';
  
negative.code:     }
    }
  
    Future<bool> hasValidPublishCheckRun(Directory package) async {
      final io.Process process = await io.Process.start(
        'flutter',
        <String>['pub', 'publish', '--', '--dry-run'],
        workingDirectory: package.path,
      );
  
      final StringBuffer outputBuffer = StringBuffer();
  
      final Completer<void> stdOutCompleter = Completer<void>();
      process.stdout.listen(
        (List<int> event) {
          io.stdout.add(event);
          outputBuffer.write(String.fromCharCodes(event));
        },
        onDone: () => stdOutCompleter.complete(),
      );
  
      final Completer<void> stdInCompleter = Completer<void>();
      process.stderr.listen(
        (List<int> event) {
          io.stderr.add(event);
          outputBuffer.write(String.fromCharCodes(event));
        },
        onDone: () => stdInCompleter.complete(),
      );
  
      if (await process.exitCode == 0) return true;
  
      await stdOutCompleter.future;
      await stdInCompleter.future;
  
      final String output = outputBuffer.toString();
      return output.contains('Package has 1 warning.') &&
          output.contains(
              'Packages with an SDK constraint on a pre-release of the Dart SDK should themselves be published as a pre-release version.');
    }
  
    Future<bool> passesPublishCheck(Directory package) async {
      final String packageName = package.basename;
      print('Checking that $packageName can be published.');
  