I’ve always been able to npm install -g mocha or npm install mocha and then just add
"scripts": {
"test": "mocha spec"
}
to package.json. That may or may not work in EVERY environment. I know, for instance, with lineman, you have to use bin/mocha. Also, if you don’t find a way around this, set your test script up for Unix and then add a second script called “wintest” or something that does whatever you need it to do in Windows. You can name your scripts whatever you want. The default ones (test, start, etc.) can be used with npm [command]; any non-standard ones (like wintest) can be used with npm run-script [command], and they will still work.
A little back story on how/why this works:
When you install a module globally, it’s available on PATH (or whatever the windows equivalent is). When you install a project dependency, if that module has any binaries, those are symlinked to node_modules/.bin and when you run npm run [some-command], npm helpfully adds node_modules/.bin to PATH for that command. So when mocha is installed globally "test": "mocha spec" uses your globally installed mocha to run tests. When it’s a project dependency, it uses the one in node_modules/.bin. The one gotcha I’ve found with this is that npm adds node_modules/.bin to the front of PATH, so local binaries will always take precedence over global ones. Almost all of the time, this is what you want, but it’s worth knowing that that’s how it works (I recently had a bug related to this).
EDIT:
Not sure at what point in npm history this changed, but npm run <script-name> now works (don’t need to do npm run-script <script-name> anymore). Possibly run-script still works as well. I’d expect it to, but I haven’t tried it.