Add prefer-node-protocol rule (#1203)

Co-authored-by: Sindre Sorhus <[email protected]>

docs/rules/prefer-node-protocol.md

@@ -0,0 +1,47 @@
+# Prefer using the `node:` protocol when importing Node.js builtin modules
+
+When importing builtin modules, it's better to use the [`node:` protocol](https://nodejs.org/api/esm.html#esm_node_imports) as it makes it perfectly clear that the package is a Node.js builtin module.
+
+And don't forget to [upvote this issue](https://github.com/nodejs/node/issues/38343) if you agree.
+
+This rule is fixable.
+
+## Fail
+
+```js
+import dgram from 'dgram';
+```
+
+```js
+export {strict as default} from 'assert';
+```
+
+```js
+import fs from 'fs/promises';
+```
+
+## Pass
+
+```js
+import dgram from 'node:dgram';
+```
+
+```js
+export {strict as default} from 'node:assert';
+```
+
+```js
+import fs from 'node:fs/promises';
+```
+
+```js
+const fs = require('fs');
+```
+
+```js
+import _ from 'lodash';
+```
+
+```js
+import fs from './fs.js';
+```

index.js

@@ -101,6 +101,7 @@ module.exports = {
 				'unicorn/prefer-modern-dom-apis': 'error',
 				'unicorn/prefer-module': 'error',
 				'unicorn/prefer-negative-index': 'error',
+				'unicorn/prefer-node-protocol': 'error',
 				'unicorn/prefer-number-properties': 'error',
 				'unicorn/prefer-optional-catch-binding': 'error',
 				'unicorn/prefer-query-selector': 'error',

package.json

@@ -42,6 +42,7 @@
 		"eslint-utils": "^2.1.0",
 		"eslint-visitor-keys": "^2.0.0",
 		"import-modules": "^2.1.0",
+		"is-builtin-module": "^3.1.0",
 		"lodash": "^4.17.21",
 		"pluralize": "^8.0.0",
 		"read-pkg-up": "^7.0.1",

readme.md

@@ -92,6 +92,7 @@ Configure it in `package.json`.
 			"unicorn/prefer-modern-dom-apis": "error",
 			"unicorn/prefer-module": "error",
 			"unicorn/prefer-negative-index": "error",
+			"unicorn/prefer-node-protocol": "error",
 			"unicorn/prefer-number-properties": "error",
 			"unicorn/prefer-optional-catch-binding": "error",
 			"unicorn/prefer-query-selector": "error",
@@ -184,6 +185,7 @@ Each rule has emojis denoting:
 | [prefer-modern-dom-apis](docs/rules/prefer-modern-dom-apis.md) | Prefer `.before()` over `.insertBefore()`, `.replaceWith()` over `.replaceChild()`, prefer one of `.before()`, `.after()`, `.append()` or `.prepend()` over `insertAdjacentText()` and `insertAdjacentElement()`. | ✅ | 🔧 |
 | [prefer-module](docs/rules/prefer-module.md) | Prefer JavaScript modules (ESM) over CommonJS. | ✅ | 🔧 |
 | [prefer-negative-index](docs/rules/prefer-negative-index.md) | Prefer negative index over `.length - index` for `{String,Array,TypedArray}#slice()` and `Array#splice()`. | ✅ | 🔧 |
+| [prefer-node-protocol](docs/rules/prefer-node-protocol.md) | Prefer using the `node:` protocol when importing Node.js builtin modules. | ✅ | 🔧 |
 | [prefer-number-properties](docs/rules/prefer-number-properties.md) | Prefer `Number` static properties over global ones. | ✅ | 🔧 |
 | [prefer-optional-catch-binding](docs/rules/prefer-optional-catch-binding.md) | Prefer omitting the `catch` binding parameter. | ✅ | 🔧 |
 | [prefer-query-selector](docs/rules/prefer-query-selector.md) | Prefer `.querySelector()` over `.getElementById()`, `.querySelectorAll()` over `.getElementsByClassName()` and `.getElementsByTagName()`. | ✅ | 🔧 |

rules/prefer-node-protocol.js

@@ -0,0 +1,53 @@
+'use strict';
+const isBuiltinModule = require('is-builtin-module');
+const getDocumentationUrl = require('./utils/get-documentation-url');
+
+const MESSAGE_ID = 'prefer-node-protocol';
+const messages = {
+	[MESSAGE_ID]: 'Prefer `node:{{moduleName}}` over `{{moduleName}}`.'
+};
+
+const selector = [
+	':matches(ImportDeclaration, ExportNamedDeclaration, ImportExpression)',
+	' > ',
+	'Literal.source'
+].join('');
+
+/** @param {import('eslint').Rule.RuleContext} context */
+const create = context => {
+	return {
+		[selector](node) {
+			const {value} = node;
+			if (
+				typeof value !== 'string' ||
+				value.startsWith('node:') ||
+				!isBuiltinModule(value)
+			) {
+				return;
+			}
+
+			const firstCharacterIndex = node.range[0] + 1;
+			context.report({
+				node,
+				messageId: MESSAGE_ID,
+				data: {moduleName: value},
+				/** @param {import('eslint').Rule.RuleFixer} fixer */
+				fix: fixer => fixer.insertTextBeforeRange([firstCharacterIndex, firstCharacterIndex], 'node:')
+			});
+		}
+	};
+};
+
+module.exports = {
+	create,
+	meta: {
+		type: 'suggestion',
+		docs: {
+			description: 'Prefer using the `node:` protocol when importing Node.js builtin modules.',
+			url: getDocumentationUrl(__filename)
+		},
+		fixable: 'code',
+		schema: [],
+		messages
+	}
+};

scripts/generate-rules-table.mjs

@@ -1,10 +1,10 @@
 // Automatically regenerates the rules table in readme.md.
 
-import {readFileSync, writeFileSync} from 'fs';
-import path from 'path';
-import package_ from '../index.js';
-import {fileURLToPath} from 'url';
+import {readFileSync, writeFileSync} from 'node:fs';
+import path from 'node:path';
+import {fileURLToPath} from 'node:url';
 import outdent from 'outdent';
+import package_ from '../index.js';
 
 const __filename = fileURLToPath(import.meta.url);
 const __dirname = path.dirname(__filename);

test/better-regex.mjs

@@ -1,4 +1,4 @@
-import {createRequire} from 'module';
+import {createRequire} from 'node:module';
 import {getTester} from './utils/test.mjs';
 
 const {test} = getTester(import.meta);

test/custom-error-definition.mjs

@@ -1,4 +1,4 @@
-import {createRequire} from 'module';
+import {createRequire} from 'node:module';
 import test from 'ava';
 import avaRuleTester from 'eslint-ava-rule-tester';
 import outdent from 'outdent';

test/no-hex-escape.mjs

@@ -1,4 +1,4 @@
-import {createRequire} from 'module';
+import {createRequire} from 'node:module';
 import test from 'ava';
 import avaRuleTester from 'eslint-ava-rule-tester';
 import {getTester} from './utils/test.mjs';

test/number-literal-case.mjs

@@ -1,4 +1,4 @@
-import {createRequire} from 'module';
+import {createRequire} from 'node:module';
 import test from 'ava';
 import avaRuleTester from 'eslint-ava-rule-tester';
 import outdent from 'outdent';

test/package.mjs

@@ -1,5 +1,5 @@
-import fs from 'fs';
-import path from 'path';
+import fs from 'node:fs';
+import path from 'node:path';
 import test from 'ava';
 import pify from 'pify';
 import index from '../index.js';

test/prefer-node-protocol.mjs

@@ -0,0 +1,79 @@
+import outdent from 'outdent';
+import {getTester} from './utils/test.mjs';
+
+const {test} = getTester(import.meta);
+
+test.snapshot({
+	valid: [
+		'import unicorn from "unicorn";',
+		'import fs from "./fs";',
+		'import fs from "unknown-builtin-module";',
+		'const fs = require("fs");',
+		'import fs from "node:fs";',
+		outdent`
+			async function foo() {
+				const fs = await import(fs);
+			}
+		`,
+		outdent`
+			async function foo() {
+				const fs = await import(0);
+			}
+		`,
+		outdent`
+			async function foo() {
+				const fs = await import(\`fs\`);
+			}
+		`
+	],
+	invalid: [
+		'import fs from "fs";',
+		'export {promises} from "fs";',
+		outdent`
+			async function foo() {
+				const fs = await import('fs');
+			}
+		`,
+		'import fs from "fs/promises";',
+		'export {default} from "fs/promises";',
+		outdent`
+			async function foo() {
+				const fs = await import('fs/promises');
+			}
+		`,
+		'import {promises} from "fs";',
+		'export {default as promises} from "fs";',
+		'import {promises} from \'fs\';',
+		outdent`
+			async function foo() {
+				const fs = await import("fs/promises");
+			}
+		`,
+		outdent`
+			async function foo() {
+				const fs = await import(/* escaped */"\\u{66}s/promises");
+			}
+		`,
+		'import "buffer";',
+		'import "child_process";',
+		'import "timers/promises";'
+	]
+});
+
+test.babel({
+	valid: [
+		'export fs from "node:fs";'
+	],
+	invalid: [
+		{
+			code: 'export fs from "fs";',
+			output: 'export fs from "node:fs";',
+			errors: 1
+		},
+		{
+			code: 'await import(\'assert/strict\')',
+			output: 'await import(\'node:assert/strict\')',
+			errors: 1
+		}
+	]
+});