nodejs/test/parallel/test-fs-write-stream-change-open.js

// Copyright Joyent, Inc. and other Node contributors.
//
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// copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
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// persons to whom the Software is furnished to do so, subject to the
// following conditions:
//
// The above copyright notice and this permission notice shall be included
// in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
// NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
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// USE OR OTHER DEALINGS IN THE SOFTWARE.

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

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

const file = tmpdir.resolve('write.txt');

tmpdir.refresh();

const stream = fs.WriteStream(file);
const _fs_close = fs.close;
const _fs_open = fs.open;

// Change the fs.open with an identical function after the WriteStream
// has pushed it onto its internal action queue, but before it's
// returned.  This simulates AOP-style extension of the fs lib.
fs.open = function() {
  return _fs_open.apply(fs, arguments);
};

fs.close = function(fd) {
  assert.ok(fd, 'fs.close must not be called with an undefined fd.');
  fs.close = _fs_close;
  fs.open = _fs_open;
  fs.closeSync(fd);
};

stream.write('foo');
stream.end();

process.on('exit', function() {
  assert.strictEqual(fs.open, _fs_open);
});