"npm install karma" fails on windows

I have the latest version of node installed:

C:\>npm -v
2.14.4

C:\>node -v
v4.1.2

I try installing karma via the docs and I get the following console output:

C:\xyz>npm install karma --save-dev

npm WARN optional dep failed, continuing fsevents@1.0.2

> bufferutil@1.2.1 install C:\xyz\node_modules\karma\node_modules\socket.io\node_modules\engine.io\node_modules\ws\node_modules\bufferutil
> node-gyp rebuild


C:\xyz\node_modules\karma\node_modules\socket.io\node_modules\engine.io\node_modules\ws\node_modules\bufferutil>if not defined npm_config_node_gyp (node "C:\Program Files\nodejs\node_modules\npm\bin\node-gyp-bin\\..\..\node_modules\node-gyp\bin\node-gyp.js" rebuild )  else (node  rebuild )
gyp ERR! configure error
gyp ERR! stack Error: Can't find Python executable "python", you can set the PYTHON env variable.
gyp ERR! stack     at failNoPython (C:\Program Files\nodejs\node_modules\npm\node_modules\node-gyp\lib\configure.js:116:14)
gyp ERR! stack     at C:\Program Files\nodejs\node_modules\npm\node_modules\node-gyp\lib\configure.js:71:11
gyp ERR! stack     at FSReqWrap.oncomplete (fs.js:82:15)
gyp ERR! System Windows_NT 10.0.10240
gyp ERR! command "C:\\Program Files\\nodejs\\node.exe" "C:\\Program Files\\nodejs\\node_modules\\npm\\node_modules\\node-gyp\\bin\\node-gyp.js" "rebuild"
gyp ERR! cwd C:\xyz\node_modules\karma\node_modules\socket.io\node_modules\engine.io\node_modules\ws\node_modules\bufferutil
gyp ERR! node -v v4.1.2
gyp ERR! node-gyp -v v3.0.3
gyp ERR! not ok

> utf-8-validate@1.2.1 install C:\xyz\node_modules\karma\node_modules\socket.io\node_modules\engine.io\node_modules\ws\node_modules\utf-8-validate
> node-gyp rebuild


C:\xyz\node_modules\karma\node_modules\socket.io\node_modules\engine.io\node_modules\ws\node_modules\utf-8-validate>if not defined npm_config_node_gyp (node "C:\Program Files\nodejs\node_modules\npm\bin\node-gyp-bin\\..\..\node_modules\node-gyp\bin\node-gyp.js" rebuild )  else (node  rebuild )
gyp ERR! configure error
gyp ERR! stack Error: Can't find Python executable "python", you can set the PYTHON env variable.
gyp ERR! stack     at failNoPython (C:\Program Files\nodejs\node_modules\npm\node_modules\node-gyp\lib\configure.js:116:14)
gyp ERR! stack     at C:\Program Files\nodejs\node_modules\npm\node_modules\node-gyp\lib\configure.js:71:11
gyp ERR! stack     at FSReqWrap.oncomplete (fs.js:82:15)
gyp ERR! System Windows_NT 10.0.10240
gyp ERR! command "C:\\Program Files\\nodejs\\node.exe" "C:\\Program Files\\nodejs\\node_modules\\npm\\node_modules\\node-gyp\\bin\\node-gyp.js" "rebuild"
gyp ERR! cwd C:\xyz\node_modules\karma\node_modules\socket.io\node_modules\engine.io\node_modules\ws\node_modules\utf-8-validate
gyp ERR! node -v v4.1.2
gyp ERR! node-gyp -v v3.0.3
gyp ERR! not ok
npm WARN optional dep failed, continuing bufferutil@1.2.1

> utf-8-validate@1.2.1 install C:\xyz\node_modules\karma\node_modules\socket.io\node_modules\socket.io-client\node_modules\engine.io-client\node_modules\ws\node_modules\utf-8-validate
> node-gyp rebuild


C:\xyz\node_modules\karma\node_modules\socket.io\node_modules\socket.io-client\node_modules\engine.io-client\node_modules\ws\node_modules\utf-8-validate>if not defined npm_config_node_gyp (node "C:\Program Files\nodejs\node_modules\npm\bin\node-gyp-bin\\..\..\node_modules\node-gyp\bin\node-gyp.js" rebuild )  else (node  rebuild )
gyp ERR! configure error
gyp ERR! stack Error: Can't find Python executable "python", you can set the PYTHON env variable.
gyp ERR! stack     at failNoPython (C:\Program Files\nodejs\node_modules\npm\node_modules\node-gyp\lib\configure.js:116:14)
gyp ERR! stack     at C:\Program Files\nodejs\node_modules\npm\node_modules\node-gyp\lib\configure.js:71:11
gyp ERR! stack     at FSReqWrap.oncomplete (fs.js:82:15)
gyp ERR! System Windows_NT 10.0.10240
gyp ERR! command "C:\\Program Files\\nodejs\\node.exe" "C:\\Program Files\\nodejs\\node_modules\\npm\\node_modules\\node-gyp\\bin\\node-gyp.js" "rebuild"
gyp ERR! cwd C:\xyz\node_modules\karma\node_modules\socket.io\node_modules\socket.io-client\node_modules\engine.io-client\node_modules\ws\node_modules\utf-8-validate
gyp ERR! node -v v4.1.2
gyp ERR! node-gyp -v v3.0.3
gyp ERR! not ok
npm WARN optional dep failed, continuing utf-8-validate@1.2.1

> bufferutil@1.2.1 install C:\xyz\node_modules\karma\node_modules\socket.io\node_modules\socket.io-client\node_modules\engine.io-client\node_modules\ws\node_modules\bufferutil
> node-gyp rebuild


C:\xyz\node_modules\karma\node_modules\socket.io\node_modules\socket.io-client\node_modules\engine.io-client\node_modules\ws\node_modules\bufferutil>if not defined npm_config_node_gyp (node "C:\Program Files\nodejs\node_modules\npm\bin\node-gyp-bin\\..\..\node_modules\node-gyp\bin\node-gyp.js" rebuild )  else (node  rebuild )
gyp ERR! configure error
gyp ERR! stack Error: Can't find Python executable "python", you can set the PYTHON env variable.
gyp ERR! stack     at failNoPython (C:\Program Files\nodejs\node_modules\npm\node_modules\node-gyp\lib\configure.js:116:14)
gyp ERR! stack     at C:\Program Files\nodejs\node_modules\npm\node_modules\node-gyp\lib\configure.js:71:11
gyp ERR! stack     at FSReqWrap.oncomplete (fs.js:82:15)
gyp ERR! System Windows_NT 10.0.10240
gyp ERR! command "C:\\Program Files\\nodejs\\node.exe" "C:\\Program Files\\nodejs\\node_modules\\npm\\node_modules\\node-gyp\\bin\\node-gyp.js" "rebuild"
gyp ERR! cwd C:\xyz\node_modules\karma\node_modules\socket.io\node_modules\socket.io-client\node_modules\engine.io-client\node_modules\ws\node_modules\bufferutil
gyp ERR! node -v v4.1.2
gyp ERR! node-gyp -v v3.0.3
gyp ERR! not ok
npm WARN optional dep failed, continuing utf-8-validate@1.2.1
npm WARN optional dep failed, continuing bufferutil@1.2.1
karma@0.13.10 node_modules\karma
├── di@0.0.1
├── graceful-fs@4.1.2
├── rimraf@2.4.3
├── mime@1.3.4
├── colors@1.1.2
├── http-proxy@1.11.2 (eventemitter3@1.1.1, requires-port@0.0.1)
├── dom-serialize@2.2.0 (custom-event@1.0.0, void-elements@1.0.0, extend@2.0.1, ent@2.2.0)
├── source-map@0.4.4 (amdefine@1.0.0)
├── useragent@2.1.7 (lru-cache@2.2.4)
├── glob@5.0.15 (path-is-absolute@1.0.0, inherits@2.0.1, inflight@1.0.4, once@1.3.2)
├── minimatch@2.0.10 (brace-expansion@1.1.1)
├── bluebird@2.10.2
├── optimist@0.6.1 (wordwrap@0.0.3, minimist@0.0.10)
├── connect@3.4.0 (utils-merge@1.0.0, parseurl@1.3.0, debug@2.2.0, finalhandler@0.4.0)
├── body-parser@1.14.1 (bytes@2.1.0, content-type@1.0.1, depd@1.1.0, qs@5.1.0, raw-body@2.1.4, on-finished@2.3.0, http-errors@1.3.1, debug@2.2.0, iconv-lite@0.4.12, type-is@1.6.9)
├── expand-braces@0.1.1 (array-uniq@1.0.2, array-slice@0.2.3, braces@0.1.5)
├── chokidar@1.2.0 (path-is-absolute@1.0.0, arrify@1.0.0, glob-parent@2.0.0, async-each@0.1.6, is-glob@2.0.1, is-binary-path@1.0.1, lodash.flatten@3.0.2, readdirp@2.0.0, anymatch@1.3.0)
├── log4js@0.6.27 (async@0.2.10, underscore@1.8.2, semver@4.3.6, readable-stream@1.0.33)
├── lodash@3.10.1
├── socket.io@1.3.7 (debug@2.1.0, has-binary-data@0.1.3, socket.io-parser@2.2.4, socket.io-adapter@0.3.1, engine.io@1.5.4, socket.io-client@1.3.7)
├── core-js@1.2.1
└── memoizee@0.3.9 (lru-queue@0.1.0, next-tick@0.2.2, d@0.1.1, timers-ext@0.1.0, event-emitter@0.3.4, es6-weak-map@0.1.4, es5-ext@0.10.8)

The first error seems to be that there is something configured wrong – but I don’t know what, since there are no steps to configure anything before running the command.

The second error I see is that python is required (there is no mention of this requirement in the docs, is this legitimate? do we really need to install python too?).

I’m guessing the rest of the errors will change once those two are figured out.

[sateffen]

But this is no problem with karma itself. I think it’s strange for npm to show optional dependencies a way everyone things it’s a critical error. The karma team can’t do anything about it. The only thing they could do is remove the dependencies, but this would be stupid, and not helpful at all.

I guess this has to be discussed with the guys from npm (pls check if there is already an issue open, I didn’t see one.

[sateffen]

This errors are optional dependencies, so you can ignore them and still use karma.

The point is, that some dependencies try to use some native code, that they want to compile via node-gyp (and node-gyp requires python). But they only try, so if they fail, they fall back to another (slower) implementation.

So this is actually not a problem with karma itself, it’s just the uncool presentation of npm that causes some confusion here I guess.

You do NOT need node-gyp or python for karma.