BREAKING: fs.read() & fs.write() should return objects

RyanZim · RyanZim · commit d3545d42941f · 2017-06-26T15:14:47.000-04:00
For forward-compat with util.promisify()
diff --git a/lib/fs/__tests__/multi-param.test.js b/lib/fs/__tests__/multi-param.test.js
@@ -0,0 +1,154 @@
+'use strict'
+/* eslint-env mocha */
+const assert = require('assert')
+const path = require('path')
+const crypto = require('crypto')
+const os = require('os')
+const semver = require('semver')
+const fs = require('../..')
+
+const SIZE = 1000
+
+// Used for tests on Node 7.2.0+ only
+const onNode7it = semver.gte(process.version, '7.2.0') ? it : it.skip
+
+describe('fs.read()', () => {
+  let TEST_FILE
+  let TEST_DATA
+  let TEST_FD
+
+  beforeEach(() => {
+    TEST_FILE = path.join(os.tmpdir(), 'fs-extra', 'read-test-file')
+    TEST_DATA = crypto.randomBytes(SIZE)
+    fs.writeFileSync(TEST_FILE, TEST_DATA)
+    TEST_FD = fs.openSync(TEST_FILE, 'r')
+  })
+
+  afterEach(() => {
+    return fs.close(TEST_FD)
+      .then(() => fs.remove(TEST_FILE))
+  })
+
+  describe('with promises', () => {
+    it('returns an object', () => {
+      return fs.read(TEST_FD, Buffer.alloc(SIZE), 0, SIZE, 0)
+        .then(results => {
+          const bytesRead = results.bytesRead
+          const buffer = results.buffer
+          assert.equal(bytesRead, SIZE, 'bytesRead is correct')
+          assert(buffer.equals(TEST_DATA), 'data is correct')
+        })
+    })
+
+    it('returns an object when position is not set', () => {
+      return fs.read(TEST_FD, Buffer.alloc(SIZE), 0, SIZE)
+        .then(results => {
+          const bytesRead = results.bytesRead
+          const buffer = results.buffer
+          assert.equal(bytesRead, SIZE, 'bytesRead is correct')
+          assert(buffer.equals(TEST_DATA), 'data is correct')
+        })
+    })
+  })
+
+  describe('with callbacks', () => {
+    it('works', done => {
+      fs.read(TEST_FD, Buffer.alloc(SIZE), 0, SIZE, 0, (err, bytesRead, buffer) => {
+        assert.ifError(err)
+        assert.equal(bytesRead, SIZE, 'bytesRead is correct')
+        assert(buffer.equals(TEST_DATA), 'data is correct')
+        done()
+      })
+    })
+
+    it('works when position is null', done => {
+      require('fs').read(TEST_FD, Buffer.alloc(SIZE), 0, SIZE, null, (err, bytesRead, buffer) => {
+        assert.ifError(err)
+        assert.equal(bytesRead, SIZE, 'bytesRead is correct')
+        assert(buffer.equals(TEST_DATA), 'data is correct')
+        done()
+      })
+    })
+  })
+})
+
+describe('fs.write()', () => {
+  let TEST_FILE
+  let TEST_DATA
+  let TEST_FD
+
+  beforeEach(() => {
+    TEST_FILE = path.join(os.tmpdir(), 'fs-extra', 'write-test-file')
+    TEST_DATA = crypto.randomBytes(SIZE)
+    fs.ensureDirSync(path.dirname(TEST_FILE))
+    TEST_FD = fs.openSync(TEST_FILE, 'w')
+  })
+
+  afterEach(() => {
+    return fs.close(TEST_FD)
+      .then(() => fs.remove(TEST_FILE))
+  })
+
+  describe('with promises', () => {
+    it('returns an object', () => {
+      return fs.write(TEST_FD, TEST_DATA, 0, SIZE, 0)
+        .then(results => {
+          const bytesWritten = results.bytesWritten
+          const buffer = results.buffer
+          assert.equal(bytesWritten, SIZE, 'bytesWritten is correct')
+          assert(buffer.equals(TEST_DATA), 'data is correct')
+        })
+    })
+
+    onNode7it('returns an object when minimal arguments are passed', () => {
+      return fs.write(TEST_FD, TEST_DATA)
+        .then(results => {
+          const bytesWritten = results.bytesWritten
+          const buffer = results.buffer
+          assert.equal(bytesWritten, SIZE, 'bytesWritten is correct')
+          assert(buffer.equals(TEST_DATA), 'data is correct')
+        })
+    })
+
+    it('returns an object when writing a string', () => {
+      const message = 'Hello World!'
+      return fs.write(TEST_FD, message)
+        .then(results => {
+          const bytesWritten = results.bytesWritten
+          const buffer = results.buffer
+          assert.equal(bytesWritten, message.length, 'bytesWritten is correct')
+          assert.equal(buffer, message, 'data is correct')
+        })
+    })
+  })
+
+  describe('with callbacks', () => {
+    it('works', done => {
+      fs.write(TEST_FD, TEST_DATA, 0, SIZE, 0, (err, bytesWritten, buffer) => {
+        assert.ifError(err)
+        assert.equal(bytesWritten, SIZE, 'bytesWritten is correct')
+        assert(buffer.equals(TEST_DATA), 'data is correct')
+        done()
+      })
+    })
+
+    onNode7it('works when minimal arguments are passed', done => {
+      fs.write(TEST_FD, TEST_DATA, (err, bytesWritten, buffer) => {
+        assert.ifError(err)
+        assert.equal(bytesWritten, SIZE, 'bytesWritten is correct')
+        assert(buffer.equals(TEST_DATA), 'data is correct')
+        done()
+      })
+    })
+
+    it('works when writing a string', done => {
+      const message = 'Hello World!'
+      return fs.write(TEST_FD, message, (err, bytesWritten, buffer) => {
+        assert.ifError(err)
+        assert.equal(bytesWritten, message.length, 'bytesWritten is correct')
+        assert.equal(buffer, message, 'data is correct')
+        done()
+      })
+    })
+  })
+})
diff --git a/lib/fs/index.js b/lib/fs/index.js
@@ -21,7 +21,6 @@ const api = [
   'lstat',
   'mkdir',
   'open',
-  'read',
   'readFile',
   'readdir',
   'readlink',
@@ -33,7 +32,6 @@ const api = [
   'truncate',
   'unlink',
   'utimes',
-  'write',
   'writeFile'
 ]
 // fs.mkdtemp() was added in Node.js v5.10.0, so check if it exists
@@ -59,3 +57,45 @@ exports.exists = function (filename, callback) {
     return fs.exists(filename, resolve)
   })
 }
+
+// fs.read() & fs.write need special treatment due to multiple callback args
+
+exports.read = function (fd, buffer, offset, length, position, callback) {
+  if (typeof callback === 'function') {
+    return fs.read(fd, buffer, offset, length, position, callback)
+  }
+  return new Promise((resolve, reject) => {
+    fs.read(fd, buffer, offset, length, position, (err, bytesRead, buffer) => {
+      if (err) return reject(err)
+      resolve({ bytesRead, buffer })
+    })
+  })
+}
+
+// Function signature can be
+// fs.write(fd, buffer[, offset[, length[, position]]], callback)
+// OR
+// fs.write(fd, string[, position[, encoding]], callback)
+// so we need to handle both cases
+exports.write = function (fd, buffer, a, b, c, callback) {
+  if (typeof arguments[arguments.length - 1] === 'function') {
+    return fs.write(fd, buffer, a, b, c, callback)
+  }
+
+  // Check for old, depricated fs.write(fd, string[, position[, encoding]], callback)
+  if (typeof buffer === 'string') {
+    return new Promise((resolve, reject) => {
+      fs.write(fd, buffer, a, b, (err, bytesWritten, buffer) => {
+        if (err) return reject(err)
+        resolve({ bytesWritten, buffer })
+      })
+    })
+  }
+
+  return new Promise((resolve, reject) => {
+    fs.write(fd, buffer, a, b, c, (err, bytesWritten, buffer) => {
+      if (err) return reject(err)
+      resolve({ bytesWritten, buffer })
+    })
+  })
+}
diff --git a/package.json b/package.json
@@ -48,6 +48,7 @@
     "read-dir-files": "^0.1.1",
     "rimraf": "^2.2.8",
     "secure-random": "^1.1.1",
+    "semver": "^5.3.0",
     "standard": "^10.0.2",
     "standard-markdown": "^2.3.0"
   },
