Sample gulpfile calling Karma

gulpfile-karma.js

var gulp = require('gulp');
var path = require('path');
var karma = require('karma').server;

/**
 * Run the Karma server once with the given config file path.
 */
function runKarma(configFile, cb) {
   karma.start({
      configFile: path.resolve(configFile),
      singleRun: true
   }, cb);
}

gulp.task('test', function(cb) {
   runKarma('karma.conf.js', cb);
});

gulp.task('watch', function() {
   gulp.watch('test/*.js', ['test']);
});

gulp.task('default', ['test', 'watch']);