JSPM @empty Error Demo App

This repository contains an application (jspm-empty-demo-app) and two packages (jspm-empty-dependency and jspm-empty-other-dependency) that together demonstrate a bug in jspm when setting a dependency to map to @empty.

Setup

1. jspm-empty-demo-app -- an application using jspm to manage dependencies and build a bundled javascript file meant to be loaded by the browser
2. jspm-empty-dependency -- an npm package that exports a function which displays a console.log. This package is depended on by jspm-empty-demo-app.
3. jspm-empty-other-dependency -- an locally-defined package inside the jspm-dempty-demo-app which is declared as a peerDependency in jspm-empty-dependency. The peer is imported and executed by jspm-empty-dependency. However, this package is not published to npm. It instead exists completely inside jspm-empty-demo-app and uses jspm config's path mapping to correctly route the dependency and load the file

Steps to reproduce the bug

1. Clone this repository
2. Change directory to jspm-empty-demo-app and run npm install
3. Bundle the application by running npm run bundle

Expected outcome

jspm successfully bundles the application. It ignores the jspm-empty-other-dependency peer dependency from jspm-empty-dependency and instead successfully uses the map set in the app's config.js.

Actual outcome

jspm fails to bundle the application with the following error:

> @joe-sh/[email protected] prepublish /.../jspm-empty-demo/jspm-empty-demo-app
> jspm bundle src/index.js ${npm_package_main}

     Building the bundle tree for src/index.js...

err  Error on fetch for @empty/index.js at file:///.../jspm-empty-demo/jspm-empty-demo-app/public/@empty/index.js
        Loading npm:@joe-sh/[email protected]/index.js
        Loading src/index.js
        Error: ENOENT: no such file or directory, open '/.../jspm-empty-demo/jspm-empty-demo-app/public/@empty/index.js'
npm ERR! code ELIFECYCLE
npm ERR! errno 1
npm ERR! @joe-sh/[email protected] prepublish: `jspm bundle src/index.js ${npm_package_main}`
npm ERR! Exit status 1
npm ERR!
npm ERR! Failed at the @joe-sh/[email protected] prepublish script.
npm ERR! This is probably not a problem with npm. There is likely additional logging output above.

npm ERR! A complete log of this run can be found in:
npm ERR!     /.../.npm/_logs/2018-02-23T20_10_41_989Z-debug.log

Additionally, if you open up jspm-empty-demo-app/public/jspm_packages/npm/@joe-sh/[email protected]/index.js you'll notice that it's renamed import otherDependency from '@joe-sh/jspm-empty-other-dependency/index.js' to import otherDependency from '@empty/index.js'

Observations

It seems there's a bug with the mapping of jspm-empty-other-dependency in the package.json of jspm-empty-dependency. Instead of correctly mapping the dependency to the location in the filesystem, it's actually renaming the @joe-sh/jspm-empty-other-dependency to @empty, which then produces an ENOENT error since it cannot load @empty/index.js.