node/test/parallel/test-fs-write-stream-autoclose-option.js

'use strict';
const common = require('../common');
const assert = require('assert');
const path = require('path');
const fs = require('fs');

const file = path.join(common.tmpDir, 'write-autoclose-opt1.txt');
common.refreshTmpDir();
let stream = fs.createWriteStream(file, {flags: 'w+', autoClose: false});
stream.write('Test1');
stream.end();
stream.on('finish', common.mustCall(function() {
  process.nextTick(common.mustCall(function() {
    assert.strictEqual(stream.closed, undefined);
    assert.notStrictEqual(stream.fd, null);
    next();
  }));
}));

function next() {
  // This will tell us if the fd is usable again or not
  stream = fs.createWriteStream(null, {fd: stream.fd, start: 0});
  stream.write('Test2');
  stream.end();
  stream.on('finish', common.mustCall(function() {
    assert.strictEqual(stream.closed, true);
    assert.strictEqual(stream.fd, null);
    process.nextTick(common.mustCall(next2));
  }));
}

function next2() {
  // This will test if after reusing the fd data is written properly
  fs.readFile(file, function(err, data) {
    assert(!err);
    assert.strictEqual(data.toString(), 'Test2');
    process.nextTick(common.mustCall(next3));
  });
}

function next3() {
  // This is to test success scenario where autoClose is true
  const stream = fs.createWriteStream(file, {autoClose: true});
  stream.write('Test3');
  stream.end();
  stream.on('finish', common.mustCall(function() {
    process.nextTick(common.mustCall(function() {
      assert.strictEqual(stream.closed, true);
      assert.strictEqual(stream.fd, null);
    }));
  }));
}