Tests the response of node.js child processes to various posix signals.

test-child-process-signals.js

var child_process = require('child_process'),
    assert = require('assert')

var isChild = !!(process.send),
    isMaster = ((!isChild) && (process.argv.length > 2)),
    isTopLevel = (!isMaster && !isChild)


if( isTopLevel ) {

  //**
  //* TopLevel - The program was called with no arguments. We'll run the test
  //* once for each stop-signal ('T' or 'A') in the list. (except, we'll skip
  //* SIGUSR1, because node's debugger owns that one.
  //*
  (function top_level(){

    var all_signals = [
      // A list of all posix-defined signals. "The following signals shall be supported on
      // all implementations".
      // See: <http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/signal.h.html>
      //
      // the `action` field shows 'default action', which the OS will (should) take unless
      // the signal is trapped and handled differently.
      //   T = Abnormal termination of the process.
      //   A = Abnormal termination of the process (with additional actions).
      //   I = Ignore the signal
      //   S = Stop the process
      //   C = Continue the process, if it is stopped; otherwise, ignore the signal.
      //
      { name: 'SIGABRT', action: 'A', desc: 'Process abort signal.' },
      { name: 'SIGALRM', action: 'T', desc: 'Alarm clock.' },
      { name: 'SIGBUS', action: 'A', desc: 'Access to an undefined portion of a memory object.' },
      { name: 'SIGCHLD', action: 'I', desc: 'Child process terminated, stopped, or continued. ' },
      { name: 'SIGCONT', action: 'C', desc: 'Continue executing, if stopped.' },
      { name: 'SIGFPE', action: 'A', desc: 'Erroneous arithmetic operation.' },
      { name: 'SIGHUP', action: 'T', desc: 'Hangup.' },
      { name: 'SIGILL', action: 'A', desc: 'Illegal instruction.' },
      { name: 'SIGINT', action: 'T', desc: 'Terminal interrupt signal.' },
      { name: 'SIGKILL', action: 'T', desc: 'Kill (cannot be caught or ignored).' },
      { name: 'SIGPIPE', action: 'T', desc: 'Write on a pipe with no one to read it.' },
      { name: 'SIGQUIT', action: 'A', desc: 'Terminal quit signal.' },
      { name: 'SIGSEGV', action: 'A', desc: 'Invalid memory reference.' },
      { name: 'SIGSTOP', action: 'S', desc: 'Stop executing (cannot be caught or ignored).' },
      { name: 'SIGTERM', action: 'T', desc: 'Termination signal.' },
      { name: 'SIGTSTP', action: 'S', desc: 'Terminal stop signal.' },
      { name: 'SIGTTIN', action: 'S', desc: 'Background process attempting read.' },
      { name: 'SIGTTOU', action: 'S', desc: 'Background process attempting write.' },
      { name: 'SIGUSR1', action: 'T', desc: 'User-defined signal 1.' },
      { name: 'SIGUSR2', action: 'T', desc: 'User-defined signal 2.' },
      { name: 'SIGPOLL', action: 'T', desc: 'Pollable event. ' },
      { name: 'SIGPROF', action: 'T', desc: 'Profiling timer expired. ' },
      { name: 'SIGSYS', action: 'A', desc: 'Bad system call.' },
      { name: 'SIGTRAP', action: 'A', desc: 'Trace/breakpoint trap. ' },
      { name: 'SIGURG', action: 'I', desc: 'High bandwidth data is available at a socket.' },
      { name: 'SIGVTALRM', action: 'T', desc: 'Virtual timer expired.' },
      { name: 'SIGXCPU', action: 'A', desc: 'CPU time limit exceeded.' },
      { name: 'SIGXFSZ', action: 'A', desc: 'File size limit exceeded. ' }
    ];

    var selectedActions = {T:true, A:true},
        globalResult = 0;

    function finish() {
      process.exit(globalResult);
    }

    (function testSignal(idx) {
      idx = idx||0;

      var sig = all_signals[idx];
      if( !sig ) {  finish(); return; }

      function nextTest() {
        process.nextTick(function() { testSignal(idx+1); });
      };

      // ignore signals that do not match the "selected actions"
      if( ! (sig.action in selectedActions) ) {
        nextTest();
        return;
      }

      // run the test in its own process.
      // the argument `sig.name` tells the script to be a "master"
      // and test the given signal.  (see "Master" below).
      child_process.execFile(
        process.execPath, [process.argv[1], sig.name], null,
        function(code, stdout, stderr) {
          process.stdout.write(stdout);
          process.stderr.write(stderr);

          globalResult = globalResult || code;
          nextTest()
        }
      )
    }());
  }());   //end: toplevel

} else if( isMaster ) {

  //**
  //* Master (Test Stop Signal) - The first cmdline argument will be the
  //* name of the signal to be tested.  Test it, and exit.
  //*
  (function do_master() {

    var excludedSignals = { 'SIGUSR1': 'used by v8/node debugger' },
        testSig = process.argv[2],
        tmr0 = null,
        timeout = 5000,
        reportText;

    function clean_exit(code) {
      process.removeAllListeners();
      clearTimeout(tmr0);
      process.exit(code);
    }

    process.on('uncaughtException', function (err) {
      var msg = '';
      if( err.name === 'AssertionError' ) {
        msg = err.message;
      } else {
        //throw err;
        msg = err;
      }
      if( reportText ) { msg = reportText + msg; }
      print('FAIL: '+ msg + '\n');
      clean_exit(1);
    });

    if( testSig ) {
      print(testSig + ' ...');
    } else {
      // disable the timeout if no signal was specified...
      timeout = 0;
    }

    if( testSig && (testSig in excludedSignals) ) {
      // skip "excluded" signals (treat them as ok)
      print( 'OK (skipped) ' + excludedSignals[testSig] + '\n');
      clean_exit(0);

    } else {

      // -- run the test -- //

      var didExit = false
      , didDisconnect = false

      if( timeout ) {
        tmr0 = setTimeout( function() {
          assert.ok( false, 'timeout ('+(timeout/1000)+'s): child did not respond to signal.');
        }, timeout);
      }

      child = child_process.fork(process.argv[1]);

      // child messages us, once it's up and running
      child.on('message', function(msg) {
        process.nextTick( start );
      });

      // performs the action that was requested of this test run.
      // (ie. send a signal, tell child exit, or just wait)
      function start() {
        if( testSig ) {
          child.kill(testSig);
        } else {
          print('master ['+process.pid+']\n');
          print('child ['+child.pid+']\n');
          print('waiting for child to exit... ');
        }
      }

      child.on('disconnect', function() {
          didDisconnect = true;
      });

      child.on('exit', function(exitCode, sigCode) {
        clearTimeout(tmr0);
        didExit = true;

        reportText = '[exitCode='+exitCode+', signal='+sigCode+'] ';
        //print(reportText);

        if( testSig ) {
          // verify that we got the signal we were expecting...
          assert.equal( sigCode, testSig, 'exit: reported incorrect signal');
          assert.equal( exitCode , null, 'exit: reported incorrect exitCode.')
        } else {
          assert( (exitCode != null && sigCode==null) || (exitCode == null && sigCode != null));
        }
        assert.ok( didDisconnect, '(exit) missing disconnect event, or events emitted out-of-order.');
      });

      process.on('exit', function() {
        assert.ok( didExit, 'no \'exit\' event was fired for child process' );
        assert.ok( didDisconnect , 'no \'disconnect\' event was fired for child process' );
        print('OK\n');
      });

      process.on('SIGINT', function() {
        print('interrupted!\n');
        clean_exit(-1);
      });
    }
  }());   //end: master

} else if( isChild ) {

  //**
  //* Child - created by the master, to be the recipient of the signal
  //*
  (function do_child() {

    process.send('helo');

    // child stays alive, because of ipc channel.
  }());   //end: child

} else {
  // should not happen.
  assert.ok( false, "the test script is unable to identify whether it is "+
      "master, child, or toplevel.  This should never happen");
}

// a few shared utilities
function print(str) {
  process.stderr.write(str);
}

The following results were obtained using node v0.7.9-pre (6f82b9f), on OS-X lion.

$ node test-child-process-signals.js 
SIGABRT ...OK
SIGALRM ...OK
SIGBUS ...OK
SIGFPE ...OK
SIGHUP ...OK
SIGILL ...OK
SIGINT ...FAIL: [exitCode=1, signal=null] exit: reported incorrect signal
SIGKILL ...OK
SIGPIPE ...FAIL: timeout (5s): child did not respond to signal.
SIGQUIT ...OK
SIGSEGV ...OK
SIGTERM ...FAIL: [exitCode=1, signal=null] exit: reported incorrect signal
SIGUSR1 ...OK (skipped) used by v8/node debugger
SIGUSR2 ...OK
SIGPOLL ...FAIL: Error: Unknown signal: SIGPOLL
SIGPROF ...OK
SIGSYS ...OK
SIGTRAP ...OK
SIGVTALRM ...OK
SIGXCPU ...OK
SIGXFSZ ...OK

Analysis:

1. we intentionally skipped SIGUSR1 because we know that node's debugger traps this one
2. SIGPOLL is undefined on OS-X. Darwin's headers define SIGEMT in its place. (looks like -D_POSIX_C_SOURCE might fix this, but that seems to break lots of other stuff).
3. SIGPIPE is trapped by nodejs (src/node.cc:2723). I assume this is due to "The special problem of SIGPIPE" (see: deps/uv/src/unix/ev/ev.3).
4. SIGINT, and SIGTERM are trapped by nodejs, and their handler (src/node.cc:2277), calls _exit(1). This causes the child_process to exit "normally" (with a non-zero exit code), rather than exiting "abnormally" (with a signal code).