feat(DEP0162): add codemod for fs write coercion

[syhstanley]

Summary

Adds a codemod for DEP0162 — implicit coercion of objects in fs.write() and fs.writeFileSync().

• Wraps the data parameter with String() for fs.writeFile(), fs.writeFileSync(), fs.appendFile(), fs.appendFileSync(), fs.write(), and their fs/promises variants
• Skips already-safe types: string literals, template literals, Buffer.from(), new Uint8Array(), .toString(), String() wrappers
• Handles both CommonJS require('fs') and ESM import { writeFile } from 'node:fs/promises'
• Handles destructured imports

Test plan

• 8 test cases covering all examples from fs.write() and fs.writeFileSync() coercion to string #412
• No-change test for valid types (strings, Buffers, TypedArrays)
• Destructured import test
• ESM promises API test
• All 8 tests pass via npx codemod jssg test

Closes #412

🤖 Generated with Claude Code

[AugustinMauroy]

not too bad but:

for you info you have to use this structure of testing

Codemod leverages a before ("input") + after ("expected") snapshot comparison. Codemod supports 2 options:

• 👍 Single-file fixtures

  tests/
    some-test-case-description/
      input.ts
      expected.ts
    another-test-case-description/
      input.ts
      expected.ts
  

• 👎 Directory snapshot fixtures

  tests/
    input/
      some-test-case-description.ts
      another-test-case-description.ts
    expected
      some-test-case-description.ts
      another-test-case-description.ts
  

Use the Single-file fixtures option.

[syhstanley]

Thanks for your review! Please check the new commits.

[AugustinMauroy]

LGMT !

[AugustinMauroy]

your test are failing + lint need to be fixed

[syhstanley]

Fixed

[brunocroh]

Suggested change

	{ kind: 'identifier', regex: `^${local}$` },
	{ kind: 'identifier', pattern: local },

[brunocroh]

Suggested change

	const calls = rootNode.findAll({
	const calls = rootNode.findAll<'call_expression'>({

[brunocroh]

Suggested change

	const argsNode = call.find({ rule: { kind: 'arguments' } });
	const argsNode = call.field('arguments');

[brunocroh]

Suggested change

	/**
	* Check if a text expression is already a safe type that doesn't need String() wrapping.
	* Safe types: string literals, template literals, Buffer/TypedArray expressions,
	* already-wrapped String() or .toString() calls.
	*/
	function isSafeType(text: string): boolean {
	const trimmed = text.trim();
	// String literals and template literals (', ", `)
	if (/^['"`]/.test(trimmed)) return true;
	// Already has .toString()
	if (trimmed.endsWith('.toString()')) return true;
	// Already wrapped in String() — exact match to avoid false positives like Stringify()
	if (/^String\(/.test(trimmed) && trimmed.endsWith(')')) return true;
	// Buffer.from(), Buffer.alloc(), etc.
	if (/^Buffer\.\w+\(/.test(trimmed)) return true;
	// new Uint8Array, new Int8Array, etc.
	if (
	/^new\s+(Uint8Array|Int8Array|Uint16Array|Int16Array|Uint32Array|Int32Array|Float32Array|Float64Array|DataView)\b/.test(
	trimmed,
	)
	)
	return true;
	// Numeric literal (integers and floats)
	if (/^\d+(\.\d+)?$/.test(trimmed)) return true;
	// null or undefined
	if (trimmed === 'null' || trimmed === 'undefined') return true;
	return false;
	}
	const TypedArrayRegex = `^(Uint8Array|Int8Array|Uint16Array|Int16Array|Uint32Array|Int32Array|Float32Array|Float64Array|DataView)$`;
	/**
	* Check if a text expression is already a safe type that doesn't need String() wrapping.
	* Safe types: string literals, template literals, Buffer/TypedArray expressions,
	* already-wrapped String() or .toString() calls.
	*/
	function isSafeType(node: SgNode<Js, Kinds<Js>>): boolean {
	const safe = node.find({
	constraints: {
	METHOD: {
	regex: TypedArrayRegex,
	},
	},
	rule: {
	any: [
	{ kind: 'number' },
	{ kind: 'string' },
	{ kind: 'string_fragment' },
	{ pattern: '$ANY.toString()' },
	{ pattern: '$METHOD' },
	{ pattern: 'Buffer.from($ANY)' },
	{ pattern: 'String($ANY)' },
	{ pattern: 'null' },
	{ pattern: 'undefined' },
	],
	},
	});
	return Boolean(safe);
	}