Make sure already installed packages are complete

[iarna]

That is, currently npm just assumes that the package has all of its dependencies met if its there. It should, in fact, verify this and install anything that's missing.

The multi-stage installer is skipping these too currently, but correcting that should be easy.

See also: #1341, #4956, #3124, #6349, #4037, #5465

[pedramphp]

#1341 - To me this is really a bug with NPM, at least create a sym link if you don't download dependencies.
in my use case we are loading .less file as an NPM module and we need to reference it from our module. but since the module is NOT downloaded because it is in the parent.
It is failing to work.

[iarna]

@pedramphp Your complaint "not installing a module because its installed in a parent" doesn't seem related to this issue? I'm afraid that what you're describing is going to happen MORE by design because of the implicit deduping of #6912. Typically your dependencies won't ever be installed below the current module.

If you're open to other ways of solving your problem, one would be to export their location of your less files (or other non-requireable resources, for example, css, html, images, etc) as a part of your module's interface, like this:

var path = require("path")
exports.lessDir = path.resolve(__dirname, "less-files")

Then things using the module that distributes less files can say:

var path = require("path")
var lessDir = require("my-module").lessDir
var lessFile = path.resolve(lessDir, "my-file.less")

[iarna]

Closing this as fixed in npm/npm#multi-stage