node/test/simple/test-file-write-stream.js

var common = require('../common');
var assert = require('assert');

var path = require('path'),
    fs = require('fs'),
    fn = path.join(common.tmpDir, 'write.txt'),
    file = fs.createWriteStream(fn),

    EXPECTED = '012345678910',

    callbacks = {
      open: -1,
      drain: -2,
      close: -1,
      endCb: -1
    };

file
  .addListener('open', function(fd) {
      callbacks.open++;
      assert.equal('number', typeof fd);
    })
  .addListener('error', function(err) {
      throw err;
    })
  .addListener('drain', function() {
      callbacks.drain++;
      if (callbacks.drain == -1) {
        assert.equal(EXPECTED, fs.readFileSync(fn));
        file.write(EXPECTED);
      } else if (callbacks.drain == 0) {
        assert.equal(EXPECTED + EXPECTED, fs.readFileSync(fn));
        file.end(function(err) {
          assert.ok(!err);
          callbacks.endCb++;
        });
      }
    })
  .addListener('close', function() {
      callbacks.close++;
      assert.throws(function() {
        file.write('should not work anymore');
      });

      fs.unlinkSync(fn);
    });

for (var i = 0; i < 11; i++) {
  (function(i) {
    assert.strictEqual(false, file.write(i));
  })(i);
}

process.addListener('exit', function() {
  for (var k in callbacks) {
    assert.equal(0, callbacks[k], k + ' count off by ' + callbacks[k]);
  }
});