child-exit-nodeback

Observe a child_process's 'exit' and 'close' events and transform them into events with nodeback-style arguments (error, child).

API

This module exports one function:

childExitNodeback(ee)

Given an EventEmitter ee (e.g. a child process object), subscribes to the next exit and close event and re-emits them as described below.

Returns ee.

The re-emited events are named exit:nodeback and close:nodeback. Their 2nd argument always is ee.

The 1st argument is either false or an Error object, depending on the first two arguments of the original event interpreted as exit status and kill signal, as a child_process would fire them.

The Error object will carry a property src which is set to ee, and at least one of the properties retval (the exit code) or signal.

Usage

from test.usage.js:

var childExitNodeback = require('child-exit-nodeback'),
  spawn = require('child_process').spawn;
function spawnNodeEval(js) { return spawn(process.execPath, ['-e', js]); }
 
test.add(function () {
  var child = spawnNodeEval('// no-op');
  equal(typeof child.pid, 'number');
  childExitNodeback(child);
  child.once('exit:nodeback',  test.log.args('no-op exit'));
  child.once('close:nodeback', test.log.args('no-op close'));
  test.log.expect([
    [ 'no-op exit',  false, '{ChildProcess}' ],
    [ 'no-op close', false, '{ChildProcess}' ],
  ]);
});
 
test.add(function () {
  var child = childExitNodeback(spawnNodeEval('process.exit(42)'));
  equal(typeof child.pid, 'number');
  child.once('exit:nodeback',  test.log.args('42 exit'));
  child.once('close:nodeback', test.log.args('42 close'));
  test.log.expect([
    [ '42 exit',  '{Error "Exit status 42"}', '{ChildProcess}' ],
    [ '42 close', '{Error "Exit status 42"}', '{ChildProcess}' ],
  ]);
});
 
test.add(function () {
  var child = spawnNodeEval('setTimeout(Function, 1e4);' +
    'process.kill(process.pid, "SIGHUP");');
  childExitNodeback(child);
  child.once('exit:nodeback',  test.log.args('hup exit'));
  child.once('close:nodeback', test.log.args('hup close'));
  test.log.expect([
    [ 'hup exit',  '{Error "Killed by signal SIGHUP"}', '{ChildProcess}' ],
    [ 'hup close', '{Error "Killed by signal SIGHUP"}', '{ChildProcess}' ],
  ]);
});

Known issues

• needs more/better tests and docs

 

License

ISC