Add unicorn linting rules

.eslintrc.js

@@ -10,7 +10,8 @@ module.exports = {
 		'prettier',
 		'plugin:prettier/recommended',
 		'plugin:import/recommended',
-		'plugin:import/typescript'
+		'plugin:import/typescript',
+		'plugin:unicorn/recommended'
 	],
 	ignorePatterns: [
 		'node_modules',
@@ -26,7 +27,9 @@ module.exports = {
 		{
 			files: ['*.js'],
 			rules: {
-				'@typescript-eslint/explicit-module-boundary-types': 'off'
+				'@typescript-eslint/explicit-module-boundary-types': 'off',
+				'unicorn/no-process-exit': 'off',
+				'unicorn/prefer-module': 'off'
 			}
 		},
 		{
@@ -94,6 +97,18 @@ module.exports = {
 				ignoreMemberSort: false
 			}
 		],
-		'sort-keys': ['error', 'asc', { caseSensitive: false }]
+		'sort-keys': ['error', 'asc', { caseSensitive: false }],
+		'unicorn/filename-case': 'off',
+		'unicorn/no-array-callback-reference': 'off',
+		'unicorn/no-array-reduce': 'off',
+		'unicorn/no-await-expression-member': 'off',
+		'unicorn/no-nested-ternary': 'off',
+		'unicorn/no-null': 'off',
+		'unicorn/no-this-assignment': 'off',
+		'unicorn/no-useless-undefined': 'off',
+		'unicorn/prefer-code-point': 'off',
+		'unicorn/prefer-math-trunc': 'off',
+		'unicorn/prefer-number-properties': 'off',
+		'unicorn/prefer-top-level-await': 'off'
 	}
 };

browser/src/error.ts

@@ -1,4 +1,4 @@
-import { errNoFileSystemInBrowser, error } from '../../src/utils/error';
+import { error, errorNoFileSystemInBrowser } from '../../src/utils/error';
 
 export const throwNoFileSystem = (method: string) => (): never =>
-	error(errNoFileSystemInBrowser(method));
+	error(errorNoFileSystemInBrowser(method));

browser/src/path.ts

@@ -1,4 +1,4 @@
-const ABSOLUTE_PATH_REGEX = /^(?:\/|(?:[A-Za-z]:)?[\\|/])/;
+const ABSOLUTE_PATH_REGEX = /^(?:\/|(?:[A-Za-z]:)?[/\\|])/;
 const RELATIVE_PATH_REGEX = /^\.?\.\//;
 const ALL_BACKSLASHES_REGEX = /\\/g;
 const ANY_SLASH_REGEX = /[/\\]/;
@@ -24,10 +24,10 @@ export function dirname(path: string): string {
 	const match = /[/\\][^/\\]*$/.exec(path);
 	if (!match) return '.';
 
-	const dir = path.slice(0, -match[0].length);
+	const directory = path.slice(0, -match[0].length);
 
-	// If `dir` is the empty string, we're at root.
-	return dir ? dir : '/';
+	// If `directory` is the empty string, we're at root.
+	return directory || '/';
 }
 
 export function extname(path: string): string {

build-plugins/clean-before-write.ts

@@ -1,13 +1,13 @@
 import fs from 'fs-extra';
 import type { Plugin } from 'rollup';
 
-export default function cleanBeforeWrite(dir: string): Plugin {
+export default function cleanBeforeWrite(directory: string): Plugin {
 	let removePromise: Promise<void> | null = null;
 	return {
 		generateBundle(_options, _bundle, isWrite) {
 			if (isWrite) {
 				// Only remove before first write, but make all writes wait on the removal
-				removePromise ||= fs.remove(dir);
+				removePromise ||= fs.remove(directory);
 				return removePromise;
 			}
 		},

build-plugins/generate-license-file.ts

@@ -4,12 +4,12 @@ import type { PluginImpl } from 'rollup';
 import license, { type Dependency, type Person } from 'rollup-plugin-license';
 
 async function generateLicenseFile(
-	dir: string,
+	directory: string,
 	dependencies: readonly Dependency[]
 ): Promise<void> {
 	const coreLicense = await fs.readFile('LICENSE-CORE.md', 'utf8');
 	const licenses = new Set<string>();
-	const dependencyLicenseTexts = Array.from(dependencies)
+	const dependencyLicenseTexts = [...dependencies]
 		.filter(({ name }) => name !== '@rollup/browser')
 		.sort(({ name: nameA }, { name: nameB }) => (nameA! > nameB! ? 1 : -1))
 		.map(({ name, license, licenseText, author, maintainers, contributors, repository }) => {
@@ -22,13 +22,13 @@ async function generateLicenseFile(
 				names.add(author.name);
 			}
 			// TODO there is an inconsistency in the rollup-plugin-license types
-			for (const person of contributors.concat(maintainers as unknown as Person[])) {
+			for (const person of [...contributors, ...(maintainers as unknown as Person[])]) {
 				if (person?.name) {
 					names.add(person.name);
 				}
 			}
 			if (names.size > 0) {
-				text += `By: ${Array.from(names).join(', ')}\n`;
+				text += `By: ${[...names].join(', ')}\n`;
 			}
 			if (repository) {
 				text += `Repository: ${(typeof repository === 'object' && repository.url) || repository}\n`;
@@ -54,10 +54,10 @@ async function generateLicenseFile(
 		coreLicense +
 		`\n# Licenses of bundled dependencies\n` +
 		`The published Rollup artifact additionally contains code with the following licenses:\n` +
-		`${Array.from(licenses).join(', ')}\n\n` +
+		`${[...licenses].join(', ')}\n\n` +
 		`# Bundled dependencies:\n` +
 		dependencyLicenseTexts;
-	const licenseFile = join(dir, 'LICENSE.md');
+	const licenseFile = join(directory, 'LICENSE.md');
 	const existingLicenseText = await fs.readFile(licenseFile, 'utf8');
 	if (existingLicenseText !== licenseText) {
 		await fs.writeFile(licenseFile, licenseText);
@@ -70,7 +70,7 @@ interface LicenseHandler {
 	writeLicense: PluginImpl;
 }
 
-export default function getLicenseHandler(dir: string): LicenseHandler {
+export default function getLicenseHandler(directory: string): LicenseHandler {
 	const licenses = new Map<string, Dependency>();
 	function addLicenses(dependencies: readonly Dependency[]) {
 		for (const dependency of dependencies) {
@@ -85,7 +85,7 @@ export default function getLicenseHandler(dir: string): LicenseHandler {
 			return {
 				name: 'write-license',
 				writeBundle() {
-					return generateLicenseFile(dir, Array.from(licenses.values()));
+					return generateLicenseFile(directory, [...licenses.values()]);
 				}
 			};
 		}

build-plugins/get-banner.ts

@@ -27,5 +27,5 @@ export default async function getBanner(): Promise<string> {
 	return (getBannerPromise ||= Promise.all([
 		execPromise('git rev-parse HEAD'),
 		fs.readFile(new URL('../package.json', import.meta.url), 'utf8')
-	]).then(([{ stdout }, pkg]) => generateBanner(stdout.trim(), JSON.parse(pkg).version)));
+	]).then(([{ stdout }, package_]) => generateBanner(stdout.trim(), JSON.parse(package_).version)));
 }

cli/cli.ts

@@ -16,6 +16,7 @@ if (command.help || (process.argv.length <= 2 && process.stdin.isTTY)) {
 	console.log(`rollup v${version}`);
 } else {
 	try {
+		// eslint-disable-next-line unicorn/prefer-module
 		require('source-map-support').install();
 	} catch {
 		// do nothing

cli/logging.ts

@@ -4,35 +4,37 @@ import { bold, cyan, dim, red } from '../src/utils/colors';
 import relativeId from '../src/utils/relativeId';
 
 // log to stderr to keep `rollup main.js > bundle.js` from breaking
-export const stderr = (...args: readonly unknown[]) => process.stderr.write(`${args.join('')}\n`);
+export const stderr = (...parameters: readonly unknown[]) =>
+	process.stderr.write(`${parameters.join('')}\n`);
 
-export function handleError(err: RollupError, recover = false): void {
-	const name = err.name || err.cause?.name;
+export function handleError(error: RollupError, recover = false): void {
+	const name = error.name || error.cause?.name;
 	const nameSection = name ? `${name}: ` : '';
-	const pluginSection = err.plugin ? `(plugin ${err.plugin}) ` : '';
-	const message = `${pluginSection}${nameSection}${err.message}`;
+	const pluginSection = error.plugin ? `(plugin ${error.plugin}) ` : '';
+	const message = `${pluginSection}${nameSection}${error.message}`;
 
 	stderr(bold(red(`[!] ${bold(message.toString())}`)));
 
-	if (err.url) {
-		stderr(cyan(err.url));
+	if (error.url) {
+		stderr(cyan(error.url));
 	}
 
-	if (err.loc) {
-		stderr(`${relativeId((err.loc.file || err.id)!)} (${err.loc.line}:${err.loc.column})`);
-	} else if (err.id) {
-		stderr(relativeId(err.id));
+	if (error.loc) {
+		stderr(`${relativeId((error.loc.file || error.id)!)} (${error.loc.line}:${error.loc.column})`);
+	} else if (error.id) {
+		stderr(relativeId(error.id));
 	}
 
-	if (err.frame) {
-		stderr(dim(err.frame));
+	if (error.frame) {
+		stderr(dim(error.frame));
 	}
 
-	if (err.stack) {
-		stderr(dim(err.stack));
+	if (error.stack) {
+		stderr(dim(error.stack));
 	}
 
 	stderr('');
 
+	// eslint-disable-next-line unicorn/no-process-exit
 	if (!recover) process.exit(1);
 }

cli/run/batchWarnings.ts

@@ -51,7 +51,7 @@ export default function batchWarnings(): BatchWarnings {
 		flush() {
 			if (count === 0) return;
 
-			const codes = Array.from(deferredWarnings.keys()).sort(
+			const codes = [...deferredWarnings.keys()].sort(
 				(a, b) => deferredWarnings.get(b)!.length - deferredWarnings.get(a)!.length
 			);
 
@@ -245,8 +245,8 @@ const deferredHandlers: {
 	}
 };
 
-function title(str: string): void {
-	stderr(bold(yellow(`(!) ${str}`)));
+function title(string_: string): void {
+	stderr(bold(yellow(`(!) ${string_}`)));
 }
 
 function info(url: string): void {
@@ -258,12 +258,12 @@ interface Nested<T> {
 	key: string;
 }
 
-function nest<T extends Record<string, any>>(array: readonly T[], prop: string): Nested<T>[] {
+function nest<T extends Record<string, any>>(array: readonly T[], property: string): Nested<T>[] {
 	const nested: Nested<T>[] = [];
 	const lookup = new Map<string, Nested<T>>();
 
 	for (const item of array) {
-		const key = item[prop];
+		const key = item[property];
 		getOrCreate(lookup, key, () => {
 			const items = {
 				items: [],

cli/run/build.ts

@@ -3,7 +3,7 @@ import ms from 'pretty-ms';
 import { rollup } from '../../src/node-entry';
 import type { MergedRollupOptions } from '../../src/rollup/types';
 import { bold, cyan, green } from '../../src/utils/colors';
-import { errOnlyInlineSourcemapsForStdout } from '../../src/utils/error';
+import { errorOnlyInlineSourcemapsForStdout } from '../../src/utils/error';
 import relativeId from '../../src/utils/relativeId';
 import { handleError, stderr } from '../logging';
 import type { BatchWarnings } from './batchWarnings';
@@ -22,7 +22,7 @@ export default async function build(
 		let inputFiles: string | undefined;
 		if (typeof inputOptions.input === 'string') {
 			inputFiles = inputOptions.input;
-		} else if (inputOptions.input instanceof Array) {
+		} else if (Array.isArray(inputOptions.input)) {
 			inputFiles = inputOptions.input.join(', ');
 		} else if (typeof inputOptions.input === 'object' && inputOptions.input !== null) {
 			inputFiles = Object.values(inputOptions.input).join(', ');
@@ -34,7 +34,7 @@ export default async function build(
 	if (useStdout) {
 		const output = outputOptions[0];
 		if (output.sourcemap && output.sourcemap !== 'inline') {
-			handleError(errOnlyInlineSourcemapsForStdout());
+			handleError(errorOnlyInlineSourcemapsForStdout());
 		}
 		const { output: outputs } = await bundle.generate(output);
 		for (const file of outputs) {

cli/run/commandPlugins.ts

@@ -45,21 +45,21 @@ async function loadAndRegisterPlugin(
 	pluginText: string
 ): Promise<void> {
 	let plugin: any = null;
-	let pluginArg: any = undefined;
+	let pluginArgument: any = undefined;
 	if (pluginText[0] === '{') {
 		// -p "{transform(c,i){...}}"
 		plugin = new Function('return ' + pluginText);
 	} else {
-		const match = pluginText.match(/^([@.:/\\\w|^{}-]+)(=(.*))?$/);
+		const match = pluginText.match(/^([\w./:@\\^{|}-]+)(=(.*))?$/);
 		if (match) {
 			// -p plugin
 			// -p plugin=arg
 			pluginText = match[1];
-			pluginArg = new Function('return ' + match[3])();
+			pluginArgument = new Function('return ' + match[3])();
 		} else {
 			throw new Error(`Invalid --plugin argument format: ${JSON.stringify(pluginText)}`);
 		}
-		if (!/^\.|^rollup-plugin-|[@/\\]/.test(pluginText)) {
+		if (!/^\.|^rollup-plugin-|[/@\\]/.test(pluginText)) {
 			// Try using plugin prefix variations first if applicable.
 			// Prefix order is significant - left has higher precedence.
 			for (const prefix of ['@rollup/plugin-', 'rollup-plugin-']) {
@@ -76,12 +76,12 @@ async function loadAndRegisterPlugin(
 				if (pluginText[0] == '.') pluginText = resolve(pluginText);
 				// Windows absolute paths must be specified as file:// protocol URL
 				// Note that we do not have coverage for Windows-only code paths
-				else if (pluginText.match(/^[A-Za-z]:\\/)) {
+				else if (/^[A-Za-z]:\\/.test(pluginText)) {
 					pluginText = pathToFileURL(resolve(pluginText)).href;
 				}
 				plugin = await requireOrImport(pluginText);
-			} catch (err: any) {
-				throw new Error(`Cannot load plugin "${pluginText}": ${err.message}.`);
+			} catch (error: any) {
+				throw new Error(`Cannot load plugin "${pluginText}": ${error.message}.`);
 			}
 		}
 	}
@@ -97,12 +97,14 @@ async function loadAndRegisterPlugin(
 			)}" for Rollup to recognize it.`
 		);
 	}
-	inputOptions.plugins.push(typeof plugin === 'function' ? plugin.call(plugin, pluginArg) : plugin);
+	inputOptions.plugins.push(
+		typeof plugin === 'function' ? plugin.call(plugin, pluginArgument) : plugin
+	);
 }
 
 function getCamelizedPluginBaseName(pluginText: string): string {
 	return (pluginText.match(/(@rollup\/plugin-|rollup-plugin-)(.+)$/)?.[2] || pluginText)
-		.split(/[\\/]/)
+		.split(/[/\\]/)
 		.slice(-1)[0]
 		.split('.')[0]
 		.split('-')
@@ -112,6 +114,7 @@ function getCamelizedPluginBaseName(pluginText: string): string {
 
 async function requireOrImport(pluginPath: string): Promise<any> {
 	try {
+		// eslint-disable-next-line unicorn/prefer-module
 		return require(pluginPath);
 	} catch {
 		return import(pluginPath);

cli/run/getConfigPath.ts

@@ -1,7 +1,7 @@
 import { promises as fs } from 'node:fs';
 import { resolve } from 'node:path';
 import { cwd } from 'node:process';
-import { errMissingExternalConfig } from '../../src/utils/error';
+import { errorMissingExternalConfig } from '../../src/utils/error';
 import { handleError } from '../logging';
 
 const DEFAULT_CONFIG_BASE = 'rollup.config';
@@ -11,28 +11,30 @@ export async function getConfigPath(commandConfig: string | true): Promise<strin
 		return resolve(await findConfigFileNameInCwd());
 	}
 	if (commandConfig.slice(0, 5) === 'node:') {
-		const pkgName = commandConfig.slice(5);
+		const packageName = commandConfig.slice(5);
 		try {
-			return require.resolve(`rollup-config-${pkgName}`, { paths: [cwd()] });
+			// eslint-disable-next-line unicorn/prefer-module
+			return require.resolve(`rollup-config-${packageName}`, { paths: [cwd()] });
 		} catch {
 			try {
-				return require.resolve(pkgName, { paths: [cwd()] });
-			} catch (err: any) {
-				if (err.code === 'MODULE_NOT_FOUND') {
-					handleError(errMissingExternalConfig(commandConfig));
+				// eslint-disable-next-line unicorn/prefer-module
+				return require.resolve(packageName, { paths: [cwd()] });
+			} catch (error: any) {
+				if (error.code === 'MODULE_NOT_FOUND') {
+					handleError(errorMissingExternalConfig(commandConfig));
 				}
-				throw err;
+				throw error;
 			}
 		}
 	}
 	return resolve(commandConfig);
 }
 
 async function findConfigFileNameInCwd(): Promise<string> {
-	const filesInWorkingDir = new Set(await fs.readdir(cwd()));
+	const filesInWorkingDirectory = new Set(await fs.readdir(cwd()));
 	for (const extension of ['mjs', 'cjs', 'ts']) {
 		const fileName = `${DEFAULT_CONFIG_BASE}.${extension}`;
-		if (filesInWorkingDir.has(fileName)) return fileName;
+		if (filesInWorkingDirectory.has(fileName)) return fileName;
 	}
 	return `${DEFAULT_CONFIG_BASE}.js`;
 }