node-multidep

Install and require multiple versions of a package via npm, like so:

 var broccoli0 = multidepRequire('broccoli', '0.16.3');
var broccoli1 = multidepRequire('broccoli', '1.0.0');

This is useful for integration testing. It's perhaps not robust enough for
production code.

Installation

 npm install --save-dev multidep

Usage

Specifying which versions to install

Create a JSON spec of packages to be installed, e.g. at test/multidep.json:

 {
  "path": "test/multidep_modules",
  "versions": {
    "broccoli": ["0.16.3", "1.0.0"]
  }
}

Do not use fuzzy versions ("^0.16.0") - this will cause problems.

Installing the packages from npm

Next, run

 ./node_modules/.bin/multidep test/multidep.json

In this example, it will create test/multidep_modules and install broccoli
0.16.3 and broccoli 1.0.0 somewhere inside the test/multidep_modules
directory.

To run multidep automatically before your test suite (when you run npm test), add it as a "pretest" hook to your package.json:

 {
  "scripts": {
    "pretest": "multidep test/multidep.json",
    "test": "..."
  }
}

multidep will not redownload existing packages. If something went wrong,
delete its directory first: rm -r test/multidep_modules

multidepRequire: Requiring specific package versions

You can now require the different versions like so:

 var multidepRequire = require('multidep')('test/multidep.json');

var broccoli0 = multidepRequire('broccoli', '0.16.3');
var broccoli1 = multidepRequire('broccoli', '1.0.0');

Note that test/multidep.json is relative to the current working directory.
This is typically your project root.

multidepRequire.forEachVersion: Iterating over all versions

To iterate over each version, use the .forEachVersion helper method.

 multidepRequire.forEachVersion('broccoli', function(version, broccoli) {
  // Do stuff with the `broccoli` module
});

Testing against the master branch

Sometimes it's useful to test against your local checkout of a package. To
facility this, there is a special 'master' version for each package whose
presence is detected automatically, without being specified in
multidep.json.

First, symlink your checkout to <path>/<package>-master, e.g.

 ln -s ~/src/broccoli test/multidep_modules/broccoli-master

Then, try to require it. If it's not present (for example on a CI server),
you will get null, rather than an exception:

 var multidepRequire = require('multidep')('test/multidep.json');

var broccoliMaster = multidepRequire('broccoli', 'master');
if (broccoliMaster !== null) {
  // Do stuff
}

The multidepRequire.forEachVersion function also includes the 'master'
version automatically when it's present.