webpack resolver handles

- jsnext (import-js#103)
- resolve.packageMains (defers to jsnext:main, regardless)

resolvers/webpack/index.js

@@ -2,6 +2,7 @@ var findRoot = require('find-root')
   , path = require('path')
   , resolve = require('resolve')
   , get = require('lodash.get')
+  , find = require('array-find')
 
 var resolveAlias = require('./resolve-alias')
 
@@ -60,6 +61,7 @@ exports.resolveImport = function resolveImport(source, file, settings) {
       || ['web_modules', 'node_modules'],
 
     paths: paths,
+    packageFilter: packageFilter.bind(null, webpackConfig),
   })
 }
 
@@ -85,3 +87,32 @@ function findExternal(source, externals) {
   // else, vanilla object
   return Object.keys(externals).some(function (e) { return source === e })
 }
+
+/**
+ * webpack defaults: http://webpack.github.io/docs/configuration.html#resolve-packagemains
+ * @type {Array}
+ */
+var defaultMains = [
+  'webpack', 'browser', 'web', 'browserify', ['jam', 'main'], 'main',
+]
+
+function packageFilter(config, pkg) {
+  var altMain
+
+  // check for rollup-style first
+  if (pkg['jsnext:main']) {
+    pkg['main'] = pkg['jsnext:main']
+  } else {
+    // check for configured/default alternative main fields
+    altMain = find(
+      get(config, ['resolve', 'packageMains']) || defaultMains,
+      function (m) { return get(pkg, m) })
+
+    if (altMain) {
+      pkg['main'] = pkg[altMain]
+    }
+  }
+
+
+  return pkg
+}

resolvers/webpack/package.json

@@ -24,6 +24,7 @@
   },
   "homepage": "https://github.com/benmosher/eslint-plugin-import#readme",
   "dependencies": {
+    "array-find": "^1.0.0",
     "find-root": "^0.1.1",
     "lodash.get": "^3.7.0",
     "resolve": "^1.1.6"

resolvers/webpack/test/package-mains/jsnext/package.json

@@ -0,0 +1,4 @@
+{
+  "main": "lib/index.js",
+  "jsnext:main": "src/index.js"
+}

resolvers/webpack/test/package-mains/package.json

@@ -0,0 +1 @@
+{ "dummy": true }

resolvers/webpack/test/package-mains/webpack.alt.config.js

@@ -0,0 +1,3 @@
+exports.resolve = {
+  packageMains: ["main"], // override
+}

resolvers/webpack/test/package-mains/webpack/package.json

@@ -0,0 +1,4 @@
+{
+  "webpack": "webpack.js",
+  "main": "index.js"
+}

resolvers/webpack/test/packageMains.js

@@ -0,0 +1,32 @@
+var chai = require('chai')
+  , expect = chai.expect
+  , path = require('path')
+
+var webpack = require('../')
+
+var file = path.join(__dirname, 'package-mains', 'dummy.js')
+
+
+describe("packageMains", function () {
+
+  it("captures jsnext", function () {
+    expect(webpack.resolveImport('./jsnext', file))
+      .to.equal(path.join(__dirname, 'package-mains', 'jsnext', 'src', 'index.js'))
+  })
+
+  it("captures webpack", function () {
+    expect(webpack.resolveImport('./webpack', file))
+      .to.equal(path.join(__dirname, 'package-mains', 'webpack', 'webpack.js'))
+  })
+
+  it("uses configured packageMains, if provided", function () {
+    expect(webpack.resolveImport('./webpack', file, { config: 'webpack.alt.config.js' }))
+      .to.equal(path.join(__dirname, 'package-mains', 'webpack', 'index.js'))
+  })
+
+  it("always defers to jsnext:main, regardless of config", function () {
+    expect(webpack.resolveImport('./jsnext', file, { config: 'webpack.alt.config.js' }))
+      .to.equal(path.join(__dirname, 'package-mains', 'jsnext', 'src', 'index.js'))
+  })
+
+})