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Added check for enoent error #10

Merged
merged 1 commit into from

3 participants

Spencer Scott Feeney David Björklund
Spencer

This package is used by browser-launcher to launch a browser headlessly. When run on OSX, which doesn't have Xvfb installed by default, the call to spawn triggers an error event which is unhanded and displays this useless output:

events.js:72
        throw er; // Unhandled 'error' event
              ^
Error: spawn ENOENT
    at errnoException (child_process.js:980:11)
    at Process.ChildProcess._handle.onexit (child_process.js:771:34)

Added an listener for "error" that will pass back a useful error message when it can.

Spencer spalger added check for enoent error, as well as a general 'error' event hand…
…ler on the child process, preventing 'uncaught error event' on systems without Xvfb installed
051bdd6
Scott Feeney

Same here, on Ubuntu — I didn't have Xvfb installed, and was baffled at the spawn ENOENT error that Testling (which uses this package) threw up. A friendly error message like this would have saved me some time :+1:

David Björklund kesla merged commit d3c0c85 into from
David Björklund
Owner

So, I haven't actually tested this PR (I don't use this module frequently anymore) - could someone take a look and ping me if it works as expected?

Scott Feeney

Aw shoot. It doesn't. At least, Testling depending on browser-launcher depending on this doesn't work as expected. Now I feel bad for (implicitly) advocating for this to be merged, without trying it. Sorry about that.

What I did: uninstalled Xvfb from my system, and replaced Testling's node_modules/browser-launcher/node_modules/headless with latest master (both with and without this change). Without this change I get the ENOENT error. With this change it simply hangs, not reporting an error or anything. I'm currently trying to figure out why.

Scott Feeney

Ah, never mind. node-headless is working perfectly. It's browser-launcher's fault for not checking for and re-throwing the error, and @spenceralger has already submitted a separate PR there: substack/browser-launcher#22. Thank you @kesla for merging this!

David Björklund
Owner

Release as 0.1.7

David Björklund
Owner

And @graue thanks for helping out!

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Commits on Nov 22, 2013
  1. Spencer

    added check for enoent error, as well as a general 'error' event hand…

    spalger authored
    …ler on the child process, preventing 'uncaught error event' on systems without Xvfb installed
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Showing with 21 additions and 1 deletion.
  1. +21 −1 index.js
22 index.js
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@@ -29,18 +29,38 @@ module.exports = function headless(startnum, callback) {
// assume starting Xvfb takes less than 500 ms and continue if it hasn't
// exited during that time
var timeout = setTimeout(function() {
- childProcess.removeListener('exit', onExit);
+ cleanUpListeners();
callback(null, childProcess, servernum);
}, 500);
function onExit() {
clearTimeout(timeout);
+ cleanUpListeners();
+
servernum++;
headless(servernum, callback);
}
+ function onError (err) {
+ clearTimeout(timeout);
+ cleanUpListeners();
+
+ if (~err.message.indexOf('ENOENT')) {
+ callback(new Error('Xvfb is not installed or is not in your $PATH'));
+ } else {
+ callback(err);
+ }
+ }
+
// if Xvfb exits prematurely the servernum wasn't valid.
// Happens if there's already an X-server running on @servernum but no file was created in /tmp
childProcess.once('exit', onExit);
+ // if Xvfb is not installed, the childProcess will emit an ENOENT error
+ childProcess.once('error', onError);
+
+ function cleanUpListeners() {
+ childProcess.removeListener('exit', onExit);
+ childProcess.removeListener('error', onError);
+ }
});
}
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