refactor: use fs.promises in module loader, Part 2

browser/fs.ts

@@ -1,4 +1,7 @@
 import { throwNoFileSystem } from './error';
 
-export const readFile = throwNoFileSystem('fs.readFile');
+export const promises = {
+	readFile: throwNoFileSystem('fs.readFile')
+};
+
 export const writeFile = throwNoFileSystem('fs.writeFile');

src/ModuleLoader.ts

@@ -29,7 +29,7 @@ import {
 	errUnresolvedImport,
 	errUnresolvedImportTreatedAsExternal
 } from './utils/error';
-import { readFile } from './utils/fs';
+import { promises as fs } from './utils/fs';
 import { isAbsolute, isRelative, resolve } from './utils/path';
 import { Queue } from './utils/queue';
 import relativeId from './utils/relativeId';
@@ -240,7 +240,8 @@ export class ModuleLoader {
 		let source: LoadResult;
 		try {
 			source = await this.readQueue.run(
-				async () => (await this.pluginDriver.hookFirst('load', [id])) ?? (await readFile(id))
+				async () =>
+					(await this.pluginDriver.hookFirst('load', [id])) ?? (await fs.readFile(id, 'utf8'))
 			);
 		} catch (err: any) {
 			timeEnd('load modules', 3);

src/utils/fs.ts

@@ -1,28 +1,9 @@
-import fs from 'fs';
+import { promises as fs } from 'fs';
 import { dirname } from './path';
 
 export * from 'fs';
 
-export const readFile = (file: string): Promise<string> =>
-	new Promise<string>((fulfil, reject) =>
-		fs.readFile(file, 'utf-8', (err, contents) => (err ? reject(err) : fulfil(contents)))
-	);
-
-function mkdirpath(path: string) {
-	const dir = dirname(path);
-	fs.mkdirSync(dir, { recursive: true });
-}
-
-export function writeFile(dest: string, data: string | Uint8Array): Promise<void> {
-	return new Promise<void>((fulfil, reject) => {
-		mkdirpath(dest);
-
-		fs.writeFile(dest, data, err => {
-			if (err) {
-				reject(err);
-			} else {
-				fulfil();
-			}
-		});
-	});
+export async function writeFile(dest: string, data: string | Uint8Array): Promise<void> {
+	await fs.mkdir(dirname(dest), { recursive: true });
+	await fs.writeFile(dest, data);
 }

test/function/samples/max-parallel-file-reads-default/_config.js

@@ -1,24 +1,23 @@
 const assert = require('assert');
-const fs = require('fs');
+const { promises } = require('fs');
 
-const fsReadFile = fs.readFile;
+const fsReadFile = promises.readFile;
 let currentReads = 0;
 let maxReads = 0;
 
 module.exports = {
 	description: 'maxParallelFileReads not set',
 	before() {
-		fs.readFile = (path, options, callback) => {
+		promises.readFile = async (path, options) => {
 			currentReads++;
 			maxReads = Math.max(maxReads, currentReads);
-			fsReadFile(path, options, (err, data) => {
-				currentReads--;
-				callback(err, data);
-			});
+			const content = await fsReadFile(path, options);
+			currentReads--;
+			return content;
 		};
 	},
 	after() {
-		fs.readFile = fsReadFile;
+		promises.readFile = fsReadFile;
 		assert.strictEqual(maxReads, 5, 'Wrong number of parallel file reads: ' + maxReads);
 	}
 };

test/function/samples/max-parallel-file-reads-error/_config.js

@@ -1,8 +1,8 @@
-const fs = require('fs');
-const path = require('path');
+const { promises } = require('fs');
+const { join } = require('path');
 const { loader } = require('../../../utils.js');
 
-const fsReadFile = fs.readFile;
+const fsReadFile = promises.readFile;
 
 module.exports = {
 	description: 'maxParallelFileReads: fileRead error is forwarded',
@@ -13,19 +13,19 @@ module.exports = {
 		})
 	},
 	before() {
-		fs.readFile = (path, options, callback) => {
+		promises.readFile = (path, options) => {
 			if (path.endsWith('dep.js')) {
-				return callback(new Error('broken'));
+				throw new Error('broken');
 			}
 
-			fsReadFile(path, options, callback);
+			fsReadFile(path, options);
 		};
 	},
 	after() {
-		fs.readFile = fsReadFile;
+		promises.readFile = fsReadFile;
 	},
 	error: {
-		message: `Could not load ${path.join(__dirname, 'dep.js')} (imported by main): broken`,
-		watchFiles: ['main', path.join(__dirname, 'dep.js')]
+		message: `Could not load ${join(__dirname, 'dep.js')} (imported by main): broken`,
+		watchFiles: ['main', join(__dirname, 'dep.js')]
 	}
 };

test/function/samples/max-parallel-file-reads-infinity/_config.js

@@ -1,7 +1,7 @@
 const assert = require('assert');
-const fs = require('fs');
+const { promises } = require('fs');
 
-const fsReadFile = fs.readFile;
+const fsReadFile = promises.readFile;
 let currentReads = 0;
 let maxReads = 0;
 
@@ -11,17 +11,16 @@ module.exports = {
 		maxParallelFileReads: 0
 	},
 	before() {
-		fs.readFile = (path, options, callback) => {
+		promises.readFile = async (path, options) => {
 			currentReads++;
 			maxReads = Math.max(maxReads, currentReads);
-			fsReadFile(path, options, (err, data) => {
-				currentReads--;
-				callback(err, data);
-			});
+			const content = await fsReadFile(path, options);
+			currentReads--;
+			return content;
 		};
 	},
 	after() {
-		fs.readFile = fsReadFile;
+		promises.readFile = fsReadFile;
 		assert.strictEqual(maxReads, 5, 'Wrong number of parallel file reads: ' + maxReads);
 	}
 };

test/function/samples/max-parallel-file-reads-set/_config.js

@@ -1,7 +1,7 @@
 const assert = require('assert');
-const fs = require('fs');
+const { promises } = require('fs');
 
-const fsReadFile = fs.readFile;
+const fsReadFile = promises.readFile;
 let currentReads = 0;
 let maxReads = 0;
 
@@ -11,17 +11,16 @@ module.exports = {
 		maxParallelFileReads: 3
 	},
 	before() {
-		fs.readFile = (path, options, callback) => {
+		promises.readFile = async (path, options) => {
 			currentReads++;
 			maxReads = Math.max(maxReads, currentReads);
-			fsReadFile(path, options, (err, data) => {
-				currentReads--;
-				callback(err, data);
-			});
+			const content = await fsReadFile(path, options);
+			currentReads--;
+			return content;
 		};
 	},
 	after() {
-		fs.readFile = fsReadFile;
+		promises.readFile = fsReadFile;
 		assert.strictEqual(maxReads, 3, 'Wrong number of parallel file reads: ' + maxReads);
 	}
 };

test/function/samples/max-parallel-file-reads-with-plugin/_config.js

@@ -1,7 +1,7 @@
 const assert = require('assert');
-const fs = require('fs');
+const { promises } = require('fs');
 
-const fsReadFile = fs.readFile;
+const fsReadFile = promises.readFile;
 let currentReads = 0;
 let maxReads = 0;
 
@@ -11,26 +11,23 @@ module.exports = {
 		maxParallelFileReads: 3,
 		plugins: [
 			{
-				async load(id) {
-					return new Promise((fulfil, reject) =>
-						fs.readFile(id, 'utf-8', (err, contents) => (err ? reject(err) : fulfil(contents)))
-					);
+				load(id) {
+					return promises.readFile(id, 'utf-8');
 				}
 			}
 		]
 	},
 	before() {
-		fs.readFile = (path, options, callback) => {
+		promises.readFile = async (path, options) => {
 			currentReads++;
 			maxReads = Math.max(maxReads, currentReads);
-			fsReadFile(path, options, (err, data) => {
-				currentReads--;
-				callback(err, data);
-			});
+			const content = await fsReadFile(path, options);
+			currentReads--;
+			return content;
 		};
 	},
 	after() {
-		fs.readFile = fsReadFile;
+		promises.readFile = fsReadFile;
 		assert.strictEqual(maxReads, 3, 'Wrong number of parallel file reads: ' + maxReads);
 	}
 };