dart_entry can be a list, so syntax for that would be:
```
transformers:
    - di:
        dart_entry: 
        - web/main.dart
        - test/main_test.dart
        injectable_annotations: transformer_demo.Injectable
```

There are some limitations around the tests folder which makes it a bit wonky- primarily that the generator right now only supports types which can be imported via package: syntax, so types in the tests themselves can not be imported. I think this can be addressed if needed though (haven't prioritized it yet).