'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.txt'); common.refreshTmpDir(); 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; }; stream.write('foo'); stream.end(); process.on('exit', function() { assert.equal(fs.open, _fs_open); });