Writing codemods often requires trial and error. The package ships a dedicated dev workflow so you can iterate on transforms in isolation without writing throw-away scripts.

Commands

Command	Description
`pnpm dev`	Run `src/dev.ts` in watch mode (hot-reloads on every save)
`pnpm dev:once`	Run `src/dev.ts` once without watching

Workflow

Edit dev-snippets/test.ts — put whatever source code you want to transform into this file. It is the default input used by the dev script. You can add more files under dev-snippets/ and reference them from src/dev.ts.

Edit testCodemod() in src/dev.ts — this is your sandbox. Call testTransform() with the path to your snippet and a recast visitor that describes the transform:

const testCodemod = () => {
	testTransform("../dev-snippets/test.ts", {
		visitIdentifier(n) {
			n.node.name = "MyNewName";
			return false;
		},
	});
};

Run pnpm dev — the transformed code is printed to the console and written to dev-snippets-outputs/test.ts (gitignored). Inspect the output file to verify the transform behaves as expected.

Key Files

File	Purpose
`src/dev.ts`	Dev entry point; exports `testTransform()` and contains the editable `testCodemod()` sandbox
`dev-snippets/test.ts`	Default sample input — replace its contents freely
`dev-snippets-outputs/`	Auto-generated transform output, gitignored — safe to inspect, never committed

`testTransform(filePath, methods)`

Mirrors the production transformFile() API but instead of silently writing in place it:

Prints the transformed source to the console
Writes the result to the corresponding path under dev-snippets-outputs/

The filePath argument must point to a file inside dev-snippets/; paths outside that directory are rejected.

Inspecting the AST

src/dev.ts includes a commented-out _printSnippet() helper. Uncomment its call at the bottom of the file to log the AST of an arbitrary snippet to the console — useful when you need to know the exact node shape to target in a visitor:

const _printSnippet = () => {
	const snippet = `if (true) { console.log("potato"); }`;
	const program = parseTs(snippet).program;
	console.log(program.body[0]);
};
_printSnippet(); // uncomment to run