How to replace deprecated gulp-karma with new version of karma?

Question

Currently I am using gulp-karma for unit-testing in JS, but the current version is deprecated. How can I replace this code so I can use the new version recommended?

Old version: var karma = require('gulp-karma');

var testFiles = [
  'client/todo.js',
  'client/todo.util.js',
];

gulp.task('test', function() {
  // Be sure to return the stream 
  return gulp.src(testFiles)
    .pipe(karma({
      configFile: 'karma.conf.js',
      action: 'run'
    }))
    .on('error', function(err) {
      // Make sure failed tests cause gulp to exit non-zero 
      throw err;
    });
});

New recommended version (but not using pipes):

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

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

I specify I need to use pipes, but I always get some errors.

Answer 1

I've done a quick research, so I'm not 100% sure that this is going to work, but Id give it a try.

Requirements
* Promises support (native or via a third party library)
* stream-from-promise => npm install stream-from-promise --save-dev

First wrap your karma server into a promise (some third party libraries also offer a safer promisify fn for this):

function startKarma(){
  return new Promise( function(resolve, reject){
    karma.start({
      configFile: __dirname + '/test/karma.conf.js',
      singleRun: true
    }, function(error){
      return error ? reject(error) : resolve();
    });
}

Now create a function to create a stream out of a promise:

var StreamFromPromise = require("stream-from-promise");

function makeStream( promise ){
  return StreamFromPromise.obj( promise );
});

And now let's write your task:

gulp.task('tests', function() {
  return gulp.src(testFiles)
  .pipe( makeStream( startKarma() ))
  .on('error', function(err) {
    // Make sure failed tests cause gulp to exit non-zero 
    throw err;
  });
});

Answer 2

 var gulp = require('gulp'); var karma = require('karma').server; var testFiles = [ 'client/todo.js', 'client/todo.util.js', ]; gulp.task('tests', function(done) { return karma.start({ configFile: __dirname + '/test/karma.conf.js', singleRun: true, files: testFiles }, done); });