How to tell gruntfile to just test phantomJS on a pull request - github

Question

I have been having pull request failing on Travis/SauceLabs while the merge build works good. When I get a pull request Travis fails with this code:
ERROR [launcher.sauce]: Can not start chrome (linux)
Failed to start Sauce Connect:
Could not start Sauce Connect. Exit code 1 signal: null
How can I test incoming pull requests just on Travis and test a merge on SauceLabs?

Answer 1

It's not possible yet to run pull requests on Sauce Labs when the sauce key/pass are encrypted. This is for safety reasons to not expose the credentials in case the PR has malicious code.
So what is possible is to use the
process.env.TRAVIS_PULL_REQUEST // (string)
to distinguish a pull request from a push/merge triggered test.
So, since this enviroment variable gives you a string with the pull request number or with "false", its possible to use it as a flag. So I used this on my Gruntfile:
var pullRequest = process.env.TRAVIS_PULL_REQUEST;
tasks = pullRequest != 'false' ? 'karma:continuous' : 'karma:sauceTask';
grunt.registerTask('default:travis', tasks);
and in my :continuous task I have only PhantomJS
continuous: {
browsers: ['PhantomJS']
},