Adds tests for environment.toWebpackConfig (#1099)

* Adds tests for default webpack package config

Adds a root module to the npm pacakge to make it possible to customize
the RAILS_ROOT location. Supporting this approach means ensuring that
relative paths for various Webpack configuration items resolve relative
to the given root if it exists.

package/__tests__/environment.js

@@ -0,0 +1,77 @@
+/* global test expect, describe */
+
+// environment.js expects to find config/webpacker.yml and resolved modules from
+// the root of a Rails project
+const cwd = process.cwd();
+const chdirApp = () => process.chdir('test/test_app')
+const chdirCwd = () => process.chdir(cwd)
+chdirApp();
+
+const { resolve, join } = require('path')
+const { sync } = require('glob')
+const assert = require('assert')
+
+const { ConfigList, ConfigObject } = require('../config_types')
+
+const Environment = require('../environment')
+
+describe('Environment', () => {
+  afterAll(chdirCwd);
+
+  let environment;
+
+  describe('toWebpackConfig', () => {
+    beforeEach(() => {
+      environment = new Environment()
+    })
+
+    test('should return entry', () => {
+      const config = environment.toWebpackConfig()
+      expect(config.entry.application).toEqual(resolve('app', 'javascript', 'packs', 'application.js'))
+    })
+
+    test('should return output', () => {
+      const config = environment.toWebpackConfig()
+      expect(config.output.filename).toEqual('[name]-[chunkhash].js')
+      expect(config.output.chunkFilename).toEqual('[name]-[chunkhash].chunk.js')
+      expect(config.output.path).toEqual(resolve('public', 'packs-test'))
+      expect(config.output.publicPath).toEqual('/packs-test/')
+    })
+
+    test('should return default loader rules for each file in config/loaders', () => {
+      const config = environment.toWebpackConfig()
+      const rules = Object.keys(require('../rules'))
+      const [{ oneOf: configRules }] = config.module.rules;
+
+      expect(rules.length).toBeGreaterThan(1)
+      expect(configRules.length).toEqual(rules.length)
+    })
+
+    test('should return default plugins', () => {
+      const config = environment.toWebpackConfig()
+      expect(config.plugins.length).toEqual(4)
+    })
+
+    test('should return default resolveLoader', () => {
+      const config = environment.toWebpackConfig()
+      expect(config.resolveLoader.modules).toEqual(['node_modules'])
+    })
+
+    test('should return default resolve.modules with additions', () => {
+      const config = environment.toWebpackConfig()
+      expect(config.resolve.modules).toEqual([
+        resolve('app', 'javascript'),
+        'node_modules',
+        'app/assets',
+        '/etc/yarn',
+      ])
+    })
+
+    test('returns plugins property as Array', () => {
+      const config = environment.toWebpackConfig()
+
+      expect(config.plugins).toBeInstanceOf(Array)
+      expect(config.plugins).not.toBeInstanceOf(ConfigList)
+    })
+  })
+})

package/utils/__tests__/objectify.js

@@ -1,4 +1,5 @@
 /* global test expect */
+console.log('objectify test cwd', process.cwd());
 
 const objectify = require('../objectify')
 

test/test_app/app/javascript/packs/application.js

@@ -0,0 +1,10 @@
+/* eslint no-console:0 */
+// This file is automatically compiled by Webpack, along with any other files
+// present in this directory. You're encouraged to place your actual application logic in
+// a relevant structure within app/javascript and only use these pack files to reference
+// that code so it'll be compiled.
+//
+// To reference this file, add <%= javascript_pack_tag 'application' %> to the appropriate
+// layout file, like app/views/layouts/application.html.erb
+
+console.log('Hello World from Webpacker')

test/test_app/config/webpacker.yml

@@ -0,0 +1,65 @@
+# Note: You must restart bin/webpack-dev-server for changes to take effect
+
+default: &default
+  source_path: app/javascript
+  source_entry_path: packs
+  public_output_path: packs
+  cache_path: tmp/cache/webpacker
+
+  # Additional paths webpack should lookup modules
+  # ['app/assets', 'engine/foo/app/assets']
+  resolved_paths:
+    - app/assets
+    - /etc/yarn
+
+  # Reload manifest.json on all requests so we reload latest compiled packs
+  cache_manifest: false
+
+  extensions:
+    - .coffee
+    - .erb
+    - .js
+    - .jsx
+    - .ts
+    - .vue
+    - .sass
+    - .scss
+    - .css
+    - .png
+    - .svg
+    - .gif
+    - .jpeg
+    - .jpg
+
+development:
+  <<: *default
+  compile: true
+
+  # Reference: https://webpack.js.org/configuration/dev-server/
+  dev_server:
+    https: false
+    host: localhost
+    port: 3035
+    public: localhost:3035
+    hmr: false
+    # Inline should be set to true if using HMR
+    inline: true
+    overlay: true
+    disable_host_check: true
+    use_local_ip: false
+
+test:
+  <<: *default
+  compile: true
+
+  # Compile test packs to a separate directory
+  public_output_path: packs-test
+
+production:
+  <<: *default
+
+  # Production depends on precompilation of packs prior to booting for performance.
+  compile: false
+
+  # Cache manifest.json for performance
+  cache_manifest: true

yarn.lock

@@ -1514,7 +1514,13 @@ date-now@^0.1.4:
   version "0.1.4"
   resolved "https://registry.yarnpkg.com/date-now/-/date-now-0.1.4.tgz#eaf439fd4d4848ad74e5cc7dbef200672b9e345b"
 
-debug@^2.2.0, debug@^2.6.8:
+debug@^2.2.0:
+  version "2.6.1"
+  resolved "https://registry.yarnpkg.com/debug/-/debug-2.6.1.tgz#79855090ba2c4e3115cc7d8769491d58f0491351"
+  dependencies:
+    ms "0.7.2"
+
+debug@^2.6.8:
   version "2.6.9"
   resolved "https://registry.yarnpkg.com/debug/-/debug-2.6.9.tgz#5d128515df134ff327e90a4c93f4e077a536341f"
   dependencies:
@@ -2290,7 +2296,18 @@ glob@^6.0.4:
     once "^1.3.0"
     path-is-absolute "^1.0.0"
 
-glob@^7.0.0, glob@^7.0.3, glob@^7.0.5, glob@^7.1.1, glob@^7.1.2, glob@~7.1.1:
+glob@^7.0.0, glob@^7.0.3, glob@^7.0.5:
+  version "7.1.1"
+  resolved "https://registry.yarnpkg.com/glob/-/glob-7.1.1.tgz#805211df04faaf1c63a3600306cdf5ade50b2ec8"
+  dependencies:
+    fs.realpath "^1.0.0"
+    inflight "^1.0.4"
+    inherits "2"
+    minimatch "^3.0.2"
+    once "^1.3.0"
+    path-is-absolute "^1.0.0"
+
+glob@^7.1.1, glob@^7.1.2, glob@~7.1.1:
   version "7.1.2"
   resolved "https://registry.yarnpkg.com/glob/-/glob-7.1.2.tgz#c19c9df9a028702d678612384a6552404c636d15"
   dependencies: