nodejs/test/parallel/test-fs-read-promises-optional-params.js

'use strict';

const common = require('../common');
const fixtures = require('../common/fixtures');
const fs = require('fs');
const read = require('util').promisify(fs.read);
const assert = require('assert');
const filepath = fixtures.path('x.txt');
const fd = fs.openSync(filepath, 'r');

const expected = Buffer.from('xyz\n');
const defaultBufferAsync = Buffer.alloc(16384);
const bufferAsOption = Buffer.allocUnsafe(expected.byteLength);

read(fd, common.mustNotMutateObjectDeep({}))
  .then(function({ bytesRead, buffer }) {
    assert.strictEqual(bytesRead, expected.byteLength);
    assert.deepStrictEqual(defaultBufferAsync.byteLength, buffer.byteLength);
  })
  .then(common.mustCall());

read(fd, bufferAsOption, common.mustNotMutateObjectDeep({ position: 0 }))
  .then(function({ bytesRead, buffer }) {
    assert.strictEqual(bytesRead, expected.byteLength);
    assert.deepStrictEqual(bufferAsOption.byteLength, buffer.byteLength);
  })
  .then(common.mustCall());