Add the ability to define multiple source entry paths

This should add back the ability to namespace packs which was removed in rails#3156 at the cost of needing to specify each of the nested directories in `source_entry_path`. Defining each namespace will make sure directories like `app/javascript/src`, `app/javascript/stylesheets`, etc don't get entries assigned.

* Move the entry parsing into `parseEntryPath` in `package/utils/helpers.js`
* Change `getEntryObject` to use `parseEntryPath` and to check whether `source_entry_path` is an array
* Add a nested pack into the test app

package/environments/base.js

@@ -1,39 +1,25 @@
 /* eslint global-require: 0 */
 /* eslint import/no-dynamic-require: 0 */
 
-const { basename, dirname, join, relative, resolve } = require('path')
-const extname = require('path-complete-extname')
+const { resolve } = require('path')
 const PnpWebpackPlugin = require('pnp-webpack-plugin')
-const { sync: globSync } = require('glob')
 const WebpackAssetsManifest = require('webpack-assets-manifest')
 const webpack = require('webpack')
 const rules = require('../rules')
 const { isProduction } = require('../env')
 const config = require('../config')
-const { moduleExists } = require('../utils/helpers')
+const { moduleExists, parseEntryPath } = require('../utils/helpers')
 
 const getEntryObject = () => {
-  const entries = {}
-  const rootPath = join(config.source_path, config.source_entry_path)
-
-  globSync(`${rootPath}/*.*`).forEach((path) => {
-    const namespace = relative(join(rootPath), dirname(path))
-    const name = join(namespace, basename(path, extname(path)))
-    let assetPaths = resolve(path)
-
-    // Allows for multiple filetypes per entry (https://webpack.js.org/guides/entry-advanced/)
-    // Transforms the config object value to an array with all values under the same name
-    let previousPaths = entries[name]
-    if (previousPaths) {
-      previousPaths = Array.isArray(previousPaths)
-        ? previousPaths
-        : [previousPaths]
-      previousPaths.push(assetPaths)
-      assetPaths = previousPaths
-    }
-
-    entries[name] = assetPaths
-  })
+  let entries = {}
+
+  if (Array.isArray(config.source_entry_path)) {
+    config.source_entry_path.forEach((entryPath) => {
+      Object.assign(entries, parseEntryPath(config.source_path, entryPath))
+    }) 
+  } else {
+    entries = parseEntryPath(config.source_path, config.source_entry_path)
+  }
 
   return entries
 }

package/utils/helpers.js

@@ -1,3 +1,7 @@
+const { basename, dirname, join, relative, resolve } = require('path')
+const { sync: globSync } = require('glob')
+const extname = require('path-complete-extname')
+
 const isArray = (value) => Array.isArray(value)
 const isBoolean = (str) => /^true/.test(str) || /^false/.test(str)
 const chdirTestApp = () => {
@@ -39,6 +43,36 @@ const canProcess = (rule, fn) => {
   return null
 }
 
+const parseEntryPath = (sourcePath, entryPath) => {
+  const entries = {}
+  const rootPath = join(sourcePath, entryPath)
+
+  globSync(`${rootPath}/*.*`).forEach((path) => {
+    const namespace = relative(join(rootPath), dirname(path))
+    const name = join(namespace, basename(path, extname(path)))
+    let assetPaths = resolve(path)
+
+    // Allows for multiple filetypes per entry (https://webpack.js.org/guides/entry-advanced/)
+    // Transforms the config object value to an array with all values under the same name
+    let previousPaths = entries[name]
+    if (previousPaths) {
+      previousPaths = Array.isArray(previousPaths)
+        ? previousPaths
+        : [previousPaths]
+      previousPaths.push(assetPaths)
+      assetPaths = previousPaths
+    }
+
+    if (entryPath === '/') {
+      entries[name] = assetPaths
+    } else {
+      entries[`${entryPath.substring(1)}/${name}`] = assetPaths
+    }
+  })
+
+  return entries
+}
+
 module.exports = {
   chdirTestApp,
   chdirCwd,
@@ -47,5 +81,6 @@ module.exports = {
   ensureTrailingSlash,
   canProcess,
   moduleExists,
-  resetEnv
+  resetEnv,
+  parseEntryPath
 }

test/test_app/app/javascript/nested/pack.js

@@ -0,0 +1,3 @@
+/*
+ * Dummy file #3 for testing namespaced packs
+ */

test/test_app/config/webpacker.yml

@@ -2,7 +2,9 @@
 
 default: &default
   source_path: app/javascript
-  source_entry_path: /
+  source_entry_path:
+    - /
+    - /nested
   public_root_path: public
   public_output_path: packs
   cache_path: tmp/webpacker