$ npm run coverage

> tuleap-document@1.0.0 coverage /home/tgorka/dev/tuleap/plugins/document/scripts
> rm -rf ./coverage/* && NODE_ENV=coverage $npm_package_config_bin/karma start ./karma.conf.js && $npm_package_config_bin/http-server -os -a 0.0.0.0 -p 9000 coverage/

(node:20033) DeprecationWarning: Tapable.plugin is deprecated. Use new API on `.hooks` instead
ℹ ｢wdm｣: wait until bundle finished: noop
ℹ ｢wdm｣:
ℹ ｢wdm｣: Compiled successfully.
20 06 2019 08:42:06.220:INFO [karma-server]: Karma v3.1.4 server started at http://0.0.0.0:9876/
20 06 2019 08:42:06.223:INFO [launcher]: Launching browsers ChromiumHeadless with concurrency unlimited
20 06 2019 08:42:06.226:INFO [launcher]: Starting browser ChromiumHeadless
20 06 2019 08:42:07.628:INFO [HeadlessChrome 73.0.3683 (Fedora 0.0.0)]: Connected on socket 51vKL4Lyoulksd-TAAAA with id 37602690
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HeadlessChrome 73.0.3683 (Fedora 0.0.0): Executed 293 of 293 SUCCESS (0.849 secs / 0.63 secs)
events.js:174
      throw er; // Unhandled 'error' event
      ^

Error: listen EADDRINUSE: address already in use 0.0.0.0:9000
    at Server.setupListenHandle [as _listen2] (net.js:1279:14)
    at listenInCluster (net.js:1327:12)
    at doListen (net.js:1460:7)
    at process._tickCallback (internal/process/next_tick.js:63:19)
    at Function.Module.runMain (internal/modules/cjs/loader.js:832:11)
    at startup (internal/bootstrap/node.js:283:19)
    at bootstrapNodeJSCore (internal/bootstrap/node.js:622:3)
Emitted 'error' event at:
    at emitErrorNT (net.js:1306:8)
    at process._tickCallback (internal/process/next_tick.js:63:19)
    [... lines matching original stack trace ...]
    at bootstrapNodeJSCore (internal/bootstrap/node.js:622:3)
npm ERR! code ELIFECYCLE
npm ERR! errno 1