Configure node npm package.json so that “npm test”

Question

I have developed a node.js npm module, developing under Windows. Today I wrote some Mocha tests. After many struggles, it seemed that for npm test to work, package.json had to look like this: (there may be other options???)

"scripts": { "test": "node node_modules/mocha/bin/mocha" }

instead of what's in all the Unix based books,

"scripts": { "test": "./node_modules/.bin/mocha" }

How can I set package.json up to work on both Windows and Unix? I'm assuming that Travis-CI runs Unix, so, should I link the build to that, it will blow up with the Windows version.

I found a two year old thread where somebody requested a feature for exactly this. That thread seemed to die out. This SO question seems to be close, but it isn't exactly what I want and, frankly, I can't understand the answer. :-( Can anybody clarify?

For the time being, I am going

"scripts": {
      "test": "node node_modules/mocha/bin/mocha",
      "testOnUnixUseThis"    : "./node_modules/.bin/mocha (I think)",
      "testOnWindowsUseThis" : "node node_modules/mocha/bin/mocha"
  },

Unfortunately, you cant go npm test testOnWindowsUseThis or npm testOnWindowsUseThis. And it doesn't fix the Travis-CI issue. But at least a person who downloads the module can (hopefully) see what is going on.

Any better ideas? Am I the only person still developing under Windows??? :-)

Answer 1

How can I set package.json up to work on both Windows and Unix?

If you

• use Windows
• dislike -g global install

...this is a working solution

"scripts": {
  "test": "node node_modules/mocha/bin/mocha.js"
},

Notes:

• putting node in front shouldn't harm, and can help on Windows (.js extension is not necessarily registered to the nodejus executable, unless you set it so. Could open a text editor, an IDE or (worse) windows scripting host, Internet Explorer…)
• Adressing the script directly saves you from needing a global install. (Not judging if this is a good practice)
• forward slashes help running under linux (obviously) and do work under windows (in this scenario. Also avoids a windows pitfall: backslashes if used, would need to be doubled – since they are interpreted as escaping the following letter if used solitary).

Answer 2

Don't use global solution, I suggest you follow what the Mocha guys say:

"scripts": {  
    "test": "node_modules/.bin/mocha -w"
 },

Answer 3

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.

Answer 4

Use npm i mocha --save-dev

This will save the module as a development dependency and npm will automatically set up the executables to be used within the scripts object. If you want to use the executables outside of the scripts defined in package.json, you can install it globally as well, although note that you may end up with different versions of the package.

If you only install it globally, other people won't be happy if they try to run your tests (with the standard npm test)