anchor.diff:    await d.file('pubspec.yaml', r'''
   name: peanut_test
   
  +environment:
  +  sdk: '>=2.10.0 <3.0.0'
  +
   dev_dependencies:
     build_runner: '>=0.8.10 <2.0.0'
     build_web_compilers: '>=1.0.0 <3.0.0'
  
positive.code:   }
  }
  
  final _exampleFiles = Map.fromEntries(Directory('example')
      .listSync()
      .cast<File>()
      .map((f) => MapEntry(p.basename(f.path), f.readAsStringSync())));
  
  Future _logGitTree(GitDir gitDir, String sha, {int depth = 0}) async {
    final treeContents = await gitDir.lsTree(sha);
  
negative.code: }
  
  Future<void> _pubGet({String parent}) async {
    final proc = await Process.run(
      'pub',
      ['get', '--offline', '--no-precompile'],
      workingDirectory: p.join(d.sandbox, parent),
    );
    expect(
      proc.exitCode,
      0,
      reason: [
        'STDOUT:',
        proc.stdout as String,
        'STDERR:',
        proc.stderr as String,
      ].map((str) => str.trim()).join('\n'),
    );
  }
  
  Future<GitDir> _initGitDir() async {
  