Error installing karma with angularjs - angularjs

Question

I am going to install karma in my front end to run some TDD tests.
To do this at the first step i run this:
sudo npm install -D karma-jasmine karma-phantomjs-launcher --save
and it seems to me that every thing is fun, here is the result:
npm WARN package.json taksi_client#1.0.0 No description
npm WARN package.json taksi_client#1.0.0 No repository field.
npm WARN package.json taksi_client#1.0.0 No README data
npm http GET https://registry.npmjs.org/karma-phantomjs-launcher
npm http GET https://registry.npmjs.org/karma-jasmine
npm http 304 https://registry.npmjs.org/karma-jasmine
npm http 304 https://registry.npmjs.org/karma-phantomjs-launcher
npm http GET https://registry.npmjs.org/lodash
npm http 304 https://registry.npmjs.org/lodash
karma-jasmine#0.3.6 node_modules/karma-jasmine
karma-phantomjs-launcher#0.2.1 node_modules/karma-phantomjs-launcher
└── lodash#3.10.1
and then I ried this command
sudo npm install -g karma --save
but i get the following erorrs. and i do not know how can i fix it?
npm http GET https://registry.npmjs.org/karma
npm http 304 https://registry.npmjs.org/karma
npm ERR! error rolling back Error: EROFS, unlink '/nix/store/a5ibcbcsm473kdr75kj4gpsr28ndnknp-nodejs-0.10.26/lib/node_modules/karma'
npm ERR! error rolling back karma#0.13.15 { [Error: EROFS, unlink '/nix/store/a5ibcbcsm473kdr75kj4gpsr28ndnknp-nodejs-0.10.26/lib/node_modules/karma']
npm ERR! error rolling back errno: 56,
npm ERR! error rolling back code: 'EROFS',
npm ERR! error rolling back path: '/nix/store/a5ibcbcsm473kdr75kj4gpsr28ndnknp-nodejs-0.10.26/lib/node_modules/karma' }
npm ERR! Error: EROFS, unlink '/nix/store/a5ibcbcsm473kdr75kj4gpsr28ndnknp-nodejs-0.10.26/lib/node_modules/karma'
npm ERR! If you need help, you may report this *entire* log,
npm ERR! including the npm and node versions, at:
npm ERR! <http://github.com/npm/npm/issues>
npm ERR! System Linux 4.2.0-c9
npm ERR! command "/nix/store/a5ibcbcsm473kdr75kj4gpsr28ndnknp-nodejs-0.10.26/bin/node" "/mnt/shared/sbin/npm" "install" "-g" "karma" "--save"
npm ERR! cwd /home/ubuntu/Taxi_Driver/taksi_client
npm ERR! node -v v0.10.28
npm ERR! npm -v 1.4.3
npm ERR! path /nix/store/a5ibcbcsm473kdr75kj4gpsr28ndnknp-nodejs-0.10.26/lib/node_modules/karma
npm ERR! code EROFS
npm ERR! errno 56
npm ERR!
npm ERR! Additional logging details can be found in:
npm ERR! /home/ubuntu/Taxi_Driver/taksi_client/npm-debug.log
npm ERR! not ok code 0