Getting karma server to launch upon grunt watch - gruntjs

Question

While developing, I'm using karma and grunt to watch for file changes and run the tests.
In command line, I'd like to be able to simply enter
$ grunt watch
and have the karma server to start once, and thereafter having grunt watching for changes and running the various tasks (including karma tests) whenever files change. I don't want to enter $ karma start .
How can this be achieved?

Answer 1

Option #1
One can use the atBegin option of grunt-contrib-watch. The idea is to introduce a startup task, which will run at the startup of the watcher:
watch: {
startup: {
files: [], // This is redundant, but we get an error if not specifying files.
tasks: [ 'karma:continuous:start' ],
options: {
atBegin: true,
spawn: false
}
},
...
}
The full Gruntfile.js:
module.exports = function(grunt) {
grunt.initConfig({
pkg: grunt.file.readJSON('package.json'),
karma: {
options: {
files: [ 'client/**/*.spec.js' ],
frameworks: [ 'jasmine' ],
reporters: [ 'progress' ],
browsers: [ 'PhantomJS' ],
singleRun: true,
autoWatch: false
},
continuous: {
singleRun: false,
background: true
}
},
concat: { ... },
uglify: { ... },
watch: {
startup: {
files: [], // This is redundant, but we get an error if not specifying files.
tasks: [ 'karma:continuous:start' ],
options: {
atBegin: true,
spawn: false
}
},
js: {
files: [ '<%= concat.js.src %>' ],
tasks: [ 'concat:js', 'uglify' ]
},
karma: {
files: [ '<%= concat.js.src %>', 'src/**/test/**/*.js' ],
tasks: [ 'karma:continuous:run' ]
},
}
});
require('load-grunt-tasks')(grunt);
grunt.registerTask( 'default', [ 'concat', 'uglify', 'karma:unit:run' ] );
};
Option #2
As shown in this and this blogs, an alternative is instead of calling
$ grunt watch
one creates another task that launch the karma server:
grunt.registerTask( 'serve', [ 'karma:continuous:start', 'watch' ] );
and then calls:
$ grunt serve
The full Gruntfile.js:
module.exports = function(grunt) {
grunt.initConfig({
pkg: grunt.file.readJSON('package.json'),
karma: {
options: {
configFile: 'karma.conf.js'
},
unit: {
singleRun: true
},
continuous: {
// keep karma running in the background
background: true
}
},
concat: { ... },
uglify: { ... },
watch: {
js: {
files: [ '<%= concat.js.src %>' ],
tasks: [ 'concat:js', 'uglify' ]
},
karma: {
files: [ '<%= concat.js.src %>', 'src/**/test/**/*.js' ],
tasks: [ 'karma:continuous:run' ]
},
}
});
require('load-grunt-tasks')(grunt);
grunt.registerTask( 'default', [ 'concat', 'uglify', 'karma:unit:run' ] );
grunt.registerTask( 'serve', [ 'karma:continuous:start', 'watch' ] );
};