How can I debug a custom transformer

Question

How can I debug a (custom) transformer using the debugger in DartEditor.

I tried use the transformer shown in http://dovdev.com/smoke-and-mirrors/ but it fails.

I checked these documents but couldn't find anything about debugging.

• https://www.dartlang.org/tools/pub/assets-and-transformers.html
• https://www.dartlang.org/tools/pub/transformers/index.html

Answer 1

Since pub runs transformers in its process, inside isolates, and doesn't redirect a transformers stdout, it's fairly hard to debug from within pub itself, so the best option is to run the transformer outside of pub by setting up a barback environment along with mocked files.

The code_transformers package makes this easier. See its tests library: http://www.dartdocs.org/documentation/code_transformers/0.2.3+1/index.html#code_transformers/code_transformers-tests