Running multiCapabilities on browserstack using browserstack-local - protractor

Question

I'm working on an angular project where we have end to end tests using protractor. We use gulp-protractor to run these tests. Every thing works fine on local. Now we want to increase the number of browsers and devices under tests, so I started to change protractor.conf.js to work with browserstack.
The web application under tests is running locally, so I use browserstack-local as well.
I have a configuration working well for one browser, which test website running on local (inspired from https://github.com/browserstack/protractor-browserstack/blob/master/conf/local.conf.js).
Now, I'm trying to adapt it to run on multi-browsers (following https://github.com/browserstack/protractor-browserstack/blob/master/conf/parallel.conf.js). I end up with that configuration:
exports.config = {
framework: 'jasmine2',
onPrepare: common.onPrepare,
// The address of a running selenium server.
seleniumAddress: 'http://hub-cloud.browserstack.com/wd/hub',
commonCapabilities: {
'browserstack.user': 'OUR_USER',
'browserstack.key': 'OUR_KEY',
name: 'Taylor Wimpey e2e tests',
'browserstack.debug': 'true',
'browserName': 'chrome',
'browserstack.local': true
},
multiCapabilities: [{
browserName: 'Chrome'
},{
browserName: 'Safari'
},{
browserName: 'Firefox'
},{
browserName: 'IE'
}],
baseUrl: 'http://localhost:3000',
// Spec patterns are relative to the current working directory when
// protractor is called.
specs: [paths.e2e + '/**/*.js'],
// Options to be passed to Jasmine-node.
jasmineNodeOpts: {
showColors: true,
defaultTimeoutInterval: 30000
},
// Code to start browserstack local before start of test
beforeLaunch: function(){
console.log("Connecting local");
return new Promise(function(resolve, reject){
exports.bs_local_args = {
key: exports.config.commonCapabilities['browserstack.key'],
force: true
};
exports.bs_local = new browserstack.Local();
exports.bs_local.start(exports.bs_local_args, function(error) {
if (error) return reject(error);
console.log('Connected. Now testing...');
resolve();
});
});
},
// Code to stop browserstack local after end of test
onComplete: function(){
console.log('Stop browserstack local');
return new Promise(function(resolve){
exports.bs_local.stop(resolve);
});
}
};
// Code to support common capabilities
exports.config.multiCapabilities.forEach(function(caps){
for(var i in exports.config.commonCapabilities) {
caps[i] = caps[i] || exports.config.commonCapabilities[i];
}
});
Tests are launched and worked (my reports are generated for each browsers), but it never stop. Here the end of console logs:
...
[BS] Serving files from: .tmp/serve
[BS] Serving files from: src
Connecting local
Connected. Now testing...
[09:05:39] I/launcher - Running 4 instances of WebDriver
......F......FFF^C
so I have to kill them manually, which is not an option as at the end, tests will be running in a continuous integration server.
Does anyone knows how to get e2e tests working on multi-browsers using browserstack with the web application under test running on local?
UPDATE: browserstack support has added an example for multi-capabilities running on local on their github repo: https://github.com/browserstack/protractor-browserstack/blob/master/conf/parallel_local.conf.js
The only difference is to use afterLaunch instead of onComplete
Thanks