Clever Geek Handbook

Karma - TypeError: Unable to read property 'on' from undefined (alternative "task completion callback" called too many times in runsequence)

Running the following gulp task to start the karma server:

gulp.task('unit-test', function () {
    // Be sure to return the stream
    return gulp.src(['random text because gulp is weird'])
            .pipe(debug({verbose: true}))
            .pipe(new Server({
                    configFile: __dirname + '/test/unit/karma.conf.js',
                    singleRun: true
                  })
                  .start())
            .on('error', function (err) {
                throw err;
            });
});

causes some errors:

[17:24:50] 'unit-test' errored after 81 ms
[INFO] [17:24:50] TypeError: Cannot read property 'on' of undefined
[INFO]     at DestroyableTransform.Readable.pipe (/Users/karianna/Documents/workspace/AdoptOpenJDK_Projects/betterrev_project/betterrev/src/main/angularjsapp/node_modules/gulp-debug/node_modules/through2/node_modules/readable-stream/lib/_stream_readable.js:516:7)
[INFO]     at Gulp.<anonymous> (/Users/karianna/Documents/workspace/AdoptOpenJDK_Projects/betterrev_project/betterrev/src/main/angularjsapp/gulpfile.js:185:14)
[INFO]     at module.exports (/Users/karianna/Documents/workspace/AdoptOpenJDK_Projects/betterrev_project/betterrev/src/main/angularjsapp/node_modules/gulp/node_modules/orchestrator/lib/runTask.js:34:7)
[INFO]     at Gulp.Orchestrator._runTask (/Users/karianna/Documents/workspace/AdoptOpenJDK_Projects/betterrev_project/betterrev/src/main/angularjsapp/node_modules/gulp/node_modules/orchestrator/index.js:273:3)
[INFO]     at Gulp.Orchestrator._runStep (/Users/karianna/Documents/workspace/AdoptOpenJDK_Projects/betterrev_project/betterrev/src/main/angularjsapp/node_modules/gulp/node_modules/orchestrator/index.js:214:10)
[INFO]     at Gulp.Orchestrator.start (/Users/karianna/Documents/workspace/AdoptOpenJDK_Projects/betterrev_project/betterrev/src/main/angularjsapp/node_modules/gulp/node_modules/orchestrator/index.js:134:8)
[INFO]     at runNextSet (/Users/karianna/Documents/workspace/AdoptOpenJDK_Projects/betterrev_project/betterrev/src/main/angularjsapp/node_modules/run-sequence/index.js:79:16)
[INFO]     at Gulp.onTaskEnd (/Users/karianna/Documents/workspace/AdoptOpenJDK_Projects/betterrev_project/betterrev/src/main/angularjsapp/node_modules/run-sequence/index.js:68:5)
[INFO]     at Gulp.emit (events.js:129:20)
[INFO]     at Gulp.Orchestrator._emitTaskDone (/Users/karianna/Documents/workspace/AdoptOpenJDK_Projects/betterrev_project/betterrev/src/main/angularjsapp/node_modules/gulp/node_modules/orchestrator/index.js:264:8)
[INFO]     at /Users/karianna/Documents/workspace/AdoptOpenJDK_Projects/betterrev_project/betterrev/src/main/angularjsapp/node_modules/gulp/node_modules/orchestrator/index.js:275:23
[INFO]     at finish (/Users/karianna/Documents/workspace/AdoptOpenJDK_Projects/betterrev_project/betterrev/src/main/angularjsapp/node_modules/gulp/node_modules/orchestrator/lib/runTask.js:21:8)
[INFO]     at cb (/Users/karianna/Documents/workspace/AdoptOpenJDK_Projects/betterrev_project/betterrev/src/main/angularjsapp/node_modules/gulp/node_modules/orchestrator/lib/runTask.js:29:3)
[INFO]     at finish (/Users/karianna/Documents/workspace/AdoptOpenJDK_Projects/betterrev_project/betterrev/src/main/angularjsapp/node_modules/run-sequence/index.js:53:5)
[INFO]     at runNextSet (/Users/karianna/Documents/workspace/AdoptOpenJDK_Projects/betterrev_project/betterrev/src/main/angularjsapp/node_modules/run-sequence/index.js:81:5)
[INFO]     at Gulp.onTaskEnd (/Users/karianna/Documents/workspace/AdoptOpenJDK_Projects/betterrev_project/betterrev/src/main/angularjsapp/node_modules/run-sequence/index.js:68:5)
[INFO] [17:24:50] 'clean-build-test' errored after 290 ms
[INFO] [17:24:50] Error: [object Object]
[INFO]     at formatError (/Users/karianna/Documents/workspace/AdoptOpenJDK_Projects/betterrev_project/betterrev/src/main/angularjsapp/node_modules/gulp/bin/gulp.js:169:10)
[INFO]     at Gulp.<anonymous> (/Users/karianna/Documents/workspace/AdoptOpenJDK_Projects/betterrev_project/betterrev/src/main/angularjsapp/node_modules/gulp/bin/gulp.js:195:15)
[INFO]     at Gulp.emit (events.js:129:20)
[INFO]     at Gulp.Orchestrator._emitTaskDone (/Users/karianna/Documents/workspace/AdoptOpenJDK_Projects/betterrev_project/betterrev/src/main/angularjsapp/node_modules/gulp/node_modules/orchestrator/index.js:264:8)
[INFO]     at /Users/karianna/Documents/workspace/AdoptOpenJDK_Projects/betterrev_project/betterrev/src/main/angularjsapp/node_modules/gulp/node_modules/orchestrator/index.js:275:23
[INFO]     at finish (/Users/karianna/Documents/workspace/AdoptOpenJDK_Projects/betterrev_project/betterrev/src/main/angularjsapp/node_modules/gulp/node_modules/orchestrator/lib/runTask.js:21:8)
[INFO]     at cb (/Users/karianna/Documents/workspace/AdoptOpenJDK_Projects/betterrev_project/betterrev/src/main/angularjsapp/node_modules/gulp/node_modules/orchestrator/lib/runTask.js:29:3)
[INFO]     at finish (/Users/karianna/Documents/workspace/AdoptOpenJDK_Projects/betterrev_project/betterrev/src/main/angularjsapp/node_modules/run-sequence/index.js:53:5)
[INFO]     at Gulp.onError (/Users/karianna/Documents/workspace/AdoptOpenJDK_Projects/betterrev_project/betterrev/src/main/angularjsapp/node_modules/run-sequence/index.js:60:4)
[INFO]     at Gulp.emit (events.js:129:20)
[INFO]     at Gulp.Orchestrator._emitTaskDone (/Users/karianna/Documents/workspace/AdoptOpenJDK_Projects/betterrev_project/betterrev/src/main/angularjsapp/node_modules/gulp/node_modules/orchestrator/index.js:264:8)
[INFO]     at /Users/karianna/Documents/workspace/AdoptOpenJDK_Projects/betterrev_project/betterrev/src/main/angularjsapp/node_modules/gulp/node_modules/orchestrator/index.js:275:23
[INFO]     at finish (/Users/karianna/Documents/workspace/AdoptOpenJDK_Projects/betterrev_project/betterrev/src/main/angularjsapp/node_modules/gulp/node_modules/orchestrator/lib/runTask.js:21:8)
[INFO]     at module.exports (/Users/karianna/Documents/workspace/AdoptOpenJDK_Projects/betterrev_project/betterrev/src/main/angularjsapp/node_modules/gulp/node_modules/orchestrator/lib/runTask.js:36:10)
[INFO]     at Gulp.Orchestrator._runTask (/Users/karianna/Documents/workspace/AdoptOpenJDK_Projects/betterrev_project/betterrev/src/main/angularjsapp/node_modules/gulp/node_modules/orchestrator/index.js:273:3)
[INFO]     at Gulp.Orchestrator._runStep (/Users/karianna/Documents/workspace/AdoptOpenJDK_Projects/betterrev_project/betterrev/src/main/angularjsapp/node_modules/gulp/node_modules/orchestrator/index.js:214:10)
[INFO] [17:24:50] gulp-debug: 0 items

Interestingly though, the karma tests still pass:

...
...
20 07 2015 17:25:34.934:DEBUG [karma]: List of files has changed, trying to execute
20 07 2015 17:25:34.935:WARN [karma]: No captured browser, open http://localhost:9876/
20 07 2015 17:25:34.937:DEBUG [watcher]: Watching "/Users/karianna/Documents/workspace/AdoptOpenJDK_Projects/betterrev_project/betterrev/src/main/webapp/js/lib.js"
20 07 2015 17:25:34.938:DEBUG [watcher]: Watching "/Users/karianna/Documents/workspace/AdoptOpenJDK_Projects/betterrev_project/betterrev/src/main/webapp/js/app.js"
20 07 2015 17:25:34.938:DEBUG [watcher]: Watching "/Users/karianna/Documents/workspace/AdoptOpenJDK_Projects/betterrev_project/betterrev/src/main/angularjsapp/test/unit"
20 07 2015 17:25:34.940:INFO [karma]: Karma v0.13.2 server started at http://localhost:9876/
20 07 2015 17:25:34.943:INFO [launcher]: Starting browser PhantomJS
20 07 2015 17:25:34.944:DEBUG [temp-dir]: Creating temp dir at /var/folders/43/yyskpwq91b3b_qjxpj5nsqkh0000gn/T/karma-97139922
20 07 2015 17:25:34.946:DEBUG [launcher]: /Users/karianna/Documents/workspace/AdoptOpenJDK_Projects/betterrev_project/betterrev/src/main/angularjsapp/node_modules/phantomjs/lib/phantom/bin/phantomjs /var/folders/43/yyskpwq91b3b_qjxpj5nsqkh0000gn/T/karma-97139922/capture.js
20 07 2015 17:25:35.982:DEBUG [web-server]: serving: /Users/karianna/Documents/workspace/AdoptOpenJDK_Projects/betterrev_project/betterrev/src/main/angularjsapp/node_modules/karma/static/client.html
20 07 2015 17:25:35.991:DEBUG [web-server]: serving: /Users/karianna/Documents/workspace/AdoptOpenJDK_Projects/betterrev_project/betterrev/src/main/angularjsapp/node_modules/karma/static/karma.js
20 07 2015 17:25:36.008:DEBUG [karma]: A browser has connected on socket Rwzn4QBMQ6mTGcBFAAAA
20 07 2015 17:25:36.011:DEBUG [web-server]: upgrade /socket.io/?EIO=3&transport=websocket&sid=Rwzn4QBMQ6mTGcBFAAAA
20 07 2015 17:25:36.028:INFO [PhantomJS 1.9.8 (Mac OS X 0.0.0)]: Connected on socket Rwzn4QBMQ6mTGcBFAAAA with id 97139922
20 07 2015 17:25:36.028:DEBUG [launcher]: PhantomJS (id 97139922) captured in 1.088 secs
20 07 2015 17:25:36.029:DEBUG [karma]: All browsers are ready, executing
20 07 2015 17:25:36.034:DEBUG [web-server]: serving: /Users/karianna/Documents/workspace/AdoptOpenJDK_Projects/betterrev_project/betterrev/src/main/angularjsapp/node_modules/karma/static/context.html
20 07 2015 17:25:36.036:DEBUG [web-server]: serving (cached): /Users/karianna/Documents/workspace/AdoptOpenJDK_Projects/betterrev_project/betterrev/src/main/angularjsapp/node_modules/karma-chai-plugins/node_modules/sinon/pkg/sinon.js
20 07 2015 17:25:36.037:DEBUG [web-server]: serving (cached): /Users/karianna/Documents/workspace/AdoptOpenJDK_Projects/betterrev_project/betterrev/src/main/angularjsapp/node_modules/karma-chai-plugins/function-bind-polyfill.js
20 07 2015 17:25:36.038:DEBUG [web-server]: serving (cached): /Users/karianna/Documents/workspace/AdoptOpenJDK_Projects/betterrev_project/betterrev/src/main/webapp/js/lib.js
20 07 2015 17:25:36.048:DEBUG [web-server]: serving (cached): /Users/karianna/Documents/workspace/AdoptOpenJDK_Projects/betterrev_project/betterrev/src/main/angularjsapp/node_modules/chai/chai.js
20 07 2015 17:25:36.048:DEBUG [web-server]: serving (cached): /Users/karianna/Documents/workspace/AdoptOpenJDK_Projects/betterrev_project/betterrev/src/main/angularjsapp/node_modules/karma-chai-plugins/chai-adapter.js
20 07 2015 17:25:36.048:DEBUG [web-server]: serving (cached): /Users/karianna/Documents/workspace/AdoptOpenJDK_Projects/betterrev_project/betterrev/src/main/angularjsapp/node_modules/mocha/mocha.js
20 07 2015 17:25:36.049:DEBUG [web-server]: serving (cached): /Users/karianna/Documents/workspace/AdoptOpenJDK_Projects/betterrev_project/betterrev/src/main/angularjsapp/node_modules/karma-mocha/lib/adapter.js
20 07 2015 17:25:36.050:DEBUG [web-server]: serving (cached): /Users/karianna/Documents/workspace/AdoptOpenJDK_Projects/betterrev_project/betterrev/src/main/angularjsapp/test/unit/authenticationService.spec.js
20 07 2015 17:25:36.050:DEBUG [web-server]: serving (cached): /Users/karianna/Documents/workspace/AdoptOpenJDK_Projects/betterrev_project/betterrev/src/main/angularjsapp/test/unit/homepage.spec.js
20 07 2015 17:25:36.050:DEBUG [web-server]: serving (cached): /Users/karianna/Documents/workspace/AdoptOpenJDK_Projects/betterrev_project/betterrev/src/main/angularjsapp/node_modules/chai-as-promised/lib/chai-as-promised.js
20 07 2015 17:25:36.050:DEBUG [web-server]: serving (cached): /Users/karianna/Documents/workspace/AdoptOpenJDK_Projects/betterrev_project/betterrev/src/main/angularjsapp/node_modules/karma-chai-plugins/node_modules/sinon-chai/lib/sinon-chai.js
20 07 2015 17:25:36.051:DEBUG [web-server]: serving (cached): /Users/karianna/Documents/workspace/AdoptOpenJDK_Projects/betterrev_project/betterrev/src/main/webapp/js/app.js
....
PhantomJS 1.9.8 (Mac OS X 0.0.0): Executed 4 of 4 SUCCESS (0.001 secs / 0.003 secs)

Trying to follow the example in more detail (adding a callback in the server call):

gulp.task('unit-test', function (cb) {
    // Be sure to return the stream
    return gulp.src(['random text because gulp is weird'])
            .pipe(debug({verbose: true}))
            .pipe(new Server({
                    configFile: __dirname + '/test/unit/karma.conf.js',
                    singleRun: true
                  }, cb)
                  .start())
            .on('error', function (err) {
                throw err;
            });
});

results in errors like:

21:48:36] Error: task completion callback called too many times
    at finish (/Users/karianna/Documents/workspace/AdoptOpenJDK_Projects/betterrev_project/betterrev/src/main/angularjsapp/node_modules/gulp/node_modules/orchestrator/lib/runTask.js:15:10)
    at cb (/Users/karianna/Documents/workspace/AdoptOpenJDK_Projects/betterrev_project/betterrev/src/main/angularjsapp/node_modules/gulp/node_modules/orchestrator/lib/runTask.js:29:3)
    at removeAllListeners (/Users/karianna/Documents/workspace/AdoptOpenJDK_Projects/betterrev_project/betterrev/src/main/angularjsapp/node_modules/karma/lib/server.js:311:7)
    at Server.<anonymous> (/Users/karianna/Documents/workspace/AdoptOpenJDK_Projects/betterrev_project/betterrev/src/main/angularjsapp/node_modules/karma/lib/server.js:322:9)
    at Server.g (events.js:199:16)
    at Server.emit (events.js:129:20)
    at net.js:1419:10
    at process._tickCallback (node.js:355:11)

I think this is because I have nested callbacks (this task is part of the execution sequence, i.e.)

gulp.task('clean-build-test', function (callback) { 
  runSequence('clean-build', 'unit-test', 'integration-test', callback); 
});

I really love the noob in Node and Javascript is so happy that I am told to go away and provide better information :-).

+3


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2 answers


Generally speaking, Gulp is only responsible for creating and directing the flow. At the same time, each broker, like your new Server

-call, is responsible for returning a stream from a function pipe

. Coming from Java, I think it is easiest to think in the context of the type system to understand this. Think of Gulp as a class that implements:

interface GulpTask {
  Stream pipe(Stream stream);
}

When you reach the function you are calling in new Server

, you get a stream, but you don't return it. You don't actually return anything so that the default return value is undefined

. Thus, an error message will inform you that you can not call on

on undefined

. It's as if you had implemented:

class BrokenStream implements GulpTask {
  @Override
  public Stream pipe(Stream stream) {
    new Server(<something>);
    return null;
  }
}

The reason for this is that you are directly using karma, which is unaware of Gulp streams. This is usually not a problem as Karma is used at the end of the pipe.

At the same time, your error handler does not take effect. You need to register error handlers prior to their potential application, that is:

gulp.task('unit-test', function () {
  return gulp
    .src(['https://www.youtube.com/watch?v=6Xywqv1cDH8'])
    .on('error', function (err) { <do something> }) // Returns a handled stream.
    .pipe(<something>); // The received stream now has an error handler.
});

So your stream has an error handler attached when it is processed by the next pipe command. This handler is run as soon as any of the following commands on the pipe throws an error.

In contrast, your code's error handler will only be attached if no error occurs (if the tag new Server

returned a stream). This is why your tests run, but you get an error handler at the end. The error handler is attached afterwards to the processing of previous pipes.



Maybe you're trying to hook up an error handler to your Karma server? Then you need to call on

with different arguments on the newly created server and not on the Gulp stream. the official Karma API tells you how.

Regarding attaching the callback to the Karma server: I assume you've accepted this as a starting point: https://github.com/karma-runner/gulp-karma

Please note that you are using Karma server from stream. This is not how you usually do it.

Using the channel, the Karma server receives each individual test and triggers a creation for each one! At the same time, each server instance receives a complete task completion response after each individual test is run. Therefore, you get a second error message.

You can track this behavior by implementing your own trivial step:

var mapStream = require('map-stream');

gulp.task('unit-test', function () {
  return gulp.src(['random text because gulp is weird'])
    .pipe(debug({verbose: true}))
    .pipe(mapStream(function (file, cb) {
      console.log(file);
      return cb(null, file)
    }))
    .pipe(new Server({
      configFile: __dirname + '/test/unit/karma.conf.js',
      singleRun: true
    }).start())
}

I'm wondering why you are using streams for this purpose at all. Just define the Karma Server as your own tasks, as in the previous plugin example. Also, you need to wrap your server like this:

.pipe(mapStream(function (file, cb) {
  new Server({
    configFile: __dirname + '/test/unit/karma.conf.js',
    singleRun: true
  }, cb).start()
 }))

This way, the server fires a callback for the file step, not one of the tasks, and your application also returns a callback that can be monitored by Gulp to interact with your flow.

+4


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gulp.task('unit-test', function (cb) {
  new Server({
    configFile: __dirname + '/test/unit/karma.conf.js',
    singleRun: true
  }, cb).start();
});


0


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