anchor.diff:    Map<String, dynamic> get _sharedData =>
         resultData ?? baselineData ?? approvedResultData;
     String get name => _sharedData["name"];
  -  String get configuration => _sharedData["configuration"] ?? "";
  +  String get configuration => _sharedData["configuration"];
     String get key => "$configuration:$name";
     String get expected => _sharedData["expected"];
     String get result => (resultData ?? const {})["result"];
  
positive.code:           test.bot, () => new SplayTreeMap<String, Map<String, dynamic>>());
        final approvalData =
            newApprovals.putIfAbsent(test.key, () => <String, dynamic>{});
        final preapprovals =
            approvalData.putIfAbsent("preapprovals", () => <String, dynamic>{});
        final preapproval =
  
negative.code:     for (final test in tests) {
        if (test.approvedResultData == null) continue;
        if (test.result == null &&
            (test.approvedResultData["preapprovals"] ?? <dynamic>[]).isEmpty) {
          continue;
        }
        final approvalData = deepClone(test.approvedResultData);
        // TODO(https://github.com/dart-lang/sdk/issues/36279): Remove needless
        // fields that shouldn't be in the approvals data. Remove this 2019-04-03.
  