Che cosa significa npm in "Ignora dipendenza facoltativa fallita"?

Question

Ultima versione di nodo e npm che causa problemi nell'esecuzione di karma. Quando provo a installare il karma-cli npm i -g karma karma-cli vengo seguente avviso:

npm WARN optional Skipping failed optional dependency /chokidar/fsevents: 
npm WARN notsup Not compatible with your operating system or architecture: fsevents@1.0.8 
npm WARN optional Skipping failed optional dependency /gulp-karma/chokidar/fsevents: 
npm WARN notsup Not compatible with your operating system or architecture: fsevents@0.2.1 

E quando provo a fare funzionare karma test, ottengo errore seguente:

"C:\Program Files\nodejs\node.exe" "C:\Program Files (x86)\JetBrains\WebStorm 11.0.3\plugins\js-karma\js_reporter\karma-intellij\lib\intellijServer.js" --karmaPackageDir=C:\Users\xxx\AppData\Roaming\npm\node_modules\karma --configFile=C:\Users\xxx\Documents\project\karma.conf.js 
26 02 2016 11:24:07.871:WARN [plugin]: Cannot find plugin "karma-chrome-launcher". 
    Did you forget to install it ? 
    npm install karma-chrome-launcher --save-dev 
26 02 2016 11:24:07.877:WARN [plugin]: Cannot find plugin "karma-firefox-launcher". 
    Did you forget to install it ? 
    npm install karma-firefox-launcher --save-dev 
26 02 2016 11:24:07.878:WARN [plugin]: Cannot find plugin "karma-phantomjs-launcher". 
    Did you forget to install it ? 
    npm install karma-phantomjs-launcher --save-dev 
26 02 2016 11:24:07.879:WARN [plugin]: Cannot find plugin "karma-jasmine". 
    Did you forget to install it ? 
    npm install karma-jasmine --save-dev 
26 02 2016 11:24:07.880:WARN [plugin]: Cannot find plugin "karma-junit-reporter". 
    Did you forget to install it ? 
    npm install karma-junit-reporter --save-dev 
26 02 2016 11:24:07.885:WARN [plugin]: Cannot find plugin "karma-teamcity-reporter". 
    Did you forget to install it ? 
    npm install karma-teamcity-reporter --save-dev 
26 02 2016 11:24:07.887:WARN [plugin]: Cannot find plugin "karma-coverage". 
    Did you forget to install it ? 
    npm install karma-coverage --save-dev 
26 02 2016 11:24:07.888:WARN [plugin]: Cannot find plugin "karma-jasmine-html-reporter". 
    Did you forget to install it ? 
    npm install karma-jasmine-html-reporter --save-dev 
26 02 2016 11:24:07.889:WARN [plugin]: Cannot find plugin "karma-ng-html2js-preprocessor". 
    Did you forget to install it ? 
    npm install karma-ng-html2js-preprocessor --save-dev 
26 02 2016 11:24:07.890:WARN [plugin]: Cannot find plugin "karma-browserify". 
    Did you forget to install it ? 
    npm install karma-browserify --save-dev 
26 02 2016 11:24:07.893:WARN [preprocess]: Can not load "coverage", it is not registered! 
    Perhaps you are missing some plugin? 
26 02 2016 11:24:07.893:WARN [preprocess]: Can not load "ng-html2js", it is not registered! 
    Perhaps you are missing some plugin? 
26 02 2016 11:24:07.893:WARN [preprocess]: Can not load "browserify", it is not registered! 
    Perhaps you are missing some plugin? 
26 02 2016 11:24:07.901:WARN [reporter]: Can not load "coverage", it is not registered! 
    Perhaps you are missing some plugin? 
26 02 2016 11:24:07.901:WARN [reporter]: Can not load "junit", it is not registered! 
    Perhaps you are missing some plugin? 
C:\Users\xxx\AppData\Roaming\npm\node_modules\karma\node_modules\di\lib\injector.js:9 
     throw error('No provider for "' + name + '"!'); 
    ^

Error: No provider for "framework:jasmine"! (Resolving: framework:jasmine) 
    at error (C:\Users\xxx\AppData\Roaming\npm\node_modules\karma\node_modules\di\lib\injector.js:22:12) 
    at Object.parent.get (C:\Users\xxx\AppData\Roaming\npm\node_modules\karma\node_modules\di\lib\injector.js:9:13) 
    at get (C:\Users\xxx\AppData\Roaming\npm\node_modules\karma\node_modules\di\lib\injector.js:54:19) 
    at C:\Users\xxx\AppData\Roaming\npm\node_modules\karma\lib\server.js:138:20 
    at Array.forEach (native) 
    at Server._start (C:\Users\xxx\AppData\Roaming\npm\node_modules\karma\lib\server.js:137:21) 
    at invoke (C:\Users\xxx\AppData\Roaming\npm\node_modules\karma\node_modules\di\lib\injector.js:75:15) 
    at Server.start (C:\Users\xxx\AppData\Roaming\npm\node_modules\karma\lib\server.js:102:18) 
    at Object.<anonymous> (C:\Program Files (x86)\JetBrains\WebStorm 11.0.3\plugins\js-karma\js_reporter\karma-intellij\lib\intellijServer.js:12:13) 
    at Module._compile (module.js:410:26) 
    at Object.Module._extensions..js (module.js:417:10) 
    at Module.load (module.js:344:32) 
    at Function.Module._load (module.js:301:12) 
    at Function.Module.runMain (module.js:442:10) 
    at startup (node.js:136:18) 
    at node.js:966:3 

Process finished with exit code 1 

mio specifiche di configurazione come segue:

Node version:v4.3.0
NPM version:3.7.3

Qualsiasi aiuto sarà molto apprezzato per risolvere questo problema, non sono in grado di installare la versione di karma, penso che non sia installata correttamente nella mia macchina.

Answer 1

Questo non è un errore. È un avviso che fseventsd, che è specifico per Mac OS, non può essere installato su Linux.

Non c'è bisogno di essere allarmato, e il pacchetto che ha bisogno di fsevents funzionerà ancora - ecco perché è una dipendenza opzionale.

Dal momento che molte persone sono confuse su questo (in particolare dal momento che questo usato per essere un vero e proprio errore, non un avvertimento) c'è an open bug to make the current warning into an INFO instead