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.

See Also: The dynavers tool is based on this library. Whereas multidep provides an explicit multidepRequire call, dynavers monkey-patches Node's require mechanism, so that require calls from anywhere will use the package version you specify.

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.