@turbo/codemod Transformers

Adding new transformers

Add new transformers using the plopjs template by running:

pnpm add-transformer

New Transformers will be automatically surfaced to the transform CLI command and used by the migrate CLI command when appropriate.

How it works

Transformers are loaded automatically from the src/transforms/ directory via the loadTransforms function.

All new transformers must contain a default export that matches the Transformer type:

export type Transformer = {
  name: string;
  description: string;
  introducedIn: string;
  transformer: (args: TransformerArgs) => TransformerResults;
};

Writing a Transform

Transforms are run using the TransformRunner. This class is designed to make writing transforms as simple as possible by abstracting away all of the boilerplate that determines what should be logged, saved, or output as a result.

To use the TransformRunner:

1. Transform each file in memory (do not write it back to disk TransformRunner takes care of this depending on the options passed in by the user), and pass to TransformRunner.modifyFile method.
2. If the transform encounters an unrecoverable error, pass it to the TransformRunner.abortTransform method.
3. When all files have been modified and passed to TransformRunner.modifyFile, call TransformRunner.finish method to write the files to disk (when not running in dry mode) and log the results.