Issue running karma task from gulp

How are you running your tests with Gulp? I came up against this issue recently on OSX, running node v0.11.14 and gulp 3.8.10, whenever there were failing tests.

Changing from the recommended:

gulp.task('test', function(done) {
    karma.start({
        configFile: __dirname + '/karma.conf.js',
        singleRun: true
    }, done);
});

To:

gulp.task('test', function(done) {
    karma.start({
        configFile: __dirname + '/karma.conf.js',
        singleRun: true
    }, function() {
        done();
    });
});

…got rid of this error.

Seems to be down to how gulp handles error messages when an error is signalled in a callback. See Improve error messages on exit for more information.