nodejs/test/parallel/test-fs-promises-file-handle-append-file.js

'use strict';

const common = require('../common');

// The following tests validate base functionality for the fs/promises
// FileHandle.appendFile method.

const fs = require('fs');
const { open } = require('fs/promises');
const path = require('path');
const tmpdir = require('../common/tmpdir');
const assert = require('assert');
const tmpDir = tmpdir.path;

tmpdir.refresh();
common.crashOnUnhandledRejection();

async function validateAppendBuffer() {
  const filePath = path.resolve(tmpDir, 'tmp-append-file-buffer.txt');
  const fileHandle = await open(filePath, 'a');
  const buffer = Buffer.from('a&Dp'.repeat(100), 'utf8');

  await fileHandle.appendFile(buffer);
  const appendedFileData = fs.readFileSync(filePath);
  assert.deepStrictEqual(appendedFileData, buffer);
}

async function validateAppendString() {
  const filePath = path.resolve(tmpDir, 'tmp-append-file-string.txt');
  const fileHandle = await open(filePath, 'a');
  const string = 'x~yz'.repeat(100);

  await fileHandle.appendFile(string);
  const stringAsBuffer = Buffer.from(string, 'utf8');
  const appendedFileData = fs.readFileSync(filePath);
  assert.deepStrictEqual(appendedFileData, stringAsBuffer);
}

validateAppendBuffer()
  .then(validateAppendString)
  .then(common.mustCall());