Convert to all peer dependencies

CHANGELOG.md

@@ -20,6 +20,7 @@ environment.loaders.append('nodeModules', nodeModules)
 - Adds experimental Yarn 2 support. Note you must manually set `nodeLinker: node-modules` in your `.yarnrc.yml`.
 - Fixes dev server issues [#2898](https://github.com/rails/webpacker/pull/2898)
 - Update static files path to from `media/` to `static/`.
+- Changed all package.json dependencies to peerDependencies, so upgrading requires adding the dependencies, per the [UPGRADE GUIDE](./docs/v6_upgrade.md).
 
 ### Breaking changes
 - Removed integration installers

CONTRIBUTING.md

@@ -50,3 +50,13 @@ bundle exec rake test TEST=test/rake_tasks_test.rb
 ```
 ruby -I test test/rake_tasks_test.rb -n test_rake_webpacker_install
 ```
+
+# Testing the generator
+If you change the generator, check that install instructions work.
+
+1. Update the gemfile so that gem "webpacker" has a line like this, pointing to your install of webpacker
+   ```ruby
+   gem 'webpacker', path: "~/shakacode/forks/webpacker"
+   ```   
+2. `bundle`
+3. Run the generator confirm that you got the right changes. 

README.md

@@ -114,6 +114,17 @@ When `package.json` and/or `yarn.lock` changes, such as when pulling down change
 yarn install
 ```
 
+Note, in v6, most JS packages are peer dependencies. Thus, the installer will add the packages:
+
+```bash
+yarn add @babel/core @babel/plugin-transform-runtime @babel/preset-env @babel/runtime babel-loader \
+  compression-webpack-plugin pnp-webpack-plugin terser-webpack-plugin \
+  webpack webpack-assets-manifest webpack-cli webpack-merge webpack-sources webpack-dev-server
+```
+
+Previously, these "webpack" and "babel" packages were direct dependencies for `@rails/webpacker`. By
+making these peer dependencies, you have control over the versions used in your webpack and babel configs.
+
 ### Usage
 
 Once installed, you can start writing modern ES6-flavored JavaScript apps right away:

docs/v6_upgrade.md

@@ -44,20 +44,28 @@ Example going to a specific version:
 
   ```ruby
   # Gemfile
-  gem 'webpacker', '6.0.0.rc.5'
+  gem 'webpacker', '6.0.0.rc.6'
   ```
 
   ```bash
   bundle install
   ```
 
   ```bash
-  yarn add @rails/[email protected].5 --exact
+  yarn add @rails/[email protected].6 --exact
   ```
 
   ```bash
   bundle exec rails webpacker:install
   ```
+
+  Overwrite all files and check what changed.
+
+
+  Note, the webpacker:install will install the peer dependencies:
+  ```bash
+  yarn add @babel/core @babel/plugin-transform-runtime @babel/preset-env @babel/runtime babel-loader compression-webpack-plugin pnp-webpack-plugin terser-webpack-plugin webpack webpack-assets-manifest webpack-cli webpack-merge webpack-sources webpack-dev-server
+  ```
 
 7. Update API usage of the view helpers by changing `javascript_packs_with_chunks_tag` and `stylesheet_packs_with_chunks_tag` to `javascript_pack_tag` and `stylesheet_pack_tag`. Ensure that your layouts and views will only have **at most one call** to `javascript_pack_tag` and **at most one call** to `stylesheet_pack_tag`. You can now pass multiple bundles to these view helper methods. If you fail to changes this, you may experience performance issues, and other bugs related to multiple copies of React, like [issue 2932](https://github.com/rails/webpacker/issues/2932).  If you expose jquery globally with `expose-loader,` by using `import $ from "expose-loader?exposes=$,jQuery!jquery"` in your `app/javascript/application.js`, pass the option `defer: false` to your `javascript_pack_tag`.
 

lib/install/template.rb

@@ -66,23 +66,25 @@
 
 Dir.chdir(Rails.root) do
   if Webpacker::VERSION.match?(/^[0-9]+\.[0-9]+\.[0-9]+$/)
-    say "Installing all JavaScript dependencies [#{Webpacker::VERSION}]"
+    say "Installing @rails/webpacker@#{Webpacker::VERSION}"
     results << run("yarn add @rails/webpacker@#{Webpacker::VERSION}")
   else
-    say "Installing all JavaScript dependencies [from prerelease rails/webpacker]"
+    say "Installing @rails/webpacker@next"
     results << run("yarn add @rails/webpacker@next")
   end
 
   package_json = File.read("#{__dir__}/../../package.json")
-  webpack_version = package_json.match(/"webpack": "(.*)"/)[1]
-  webpack_cli_version = package_json.match(/"webpack-cli": "(.*)"/)[1]
+  peers = JSON.parse(package_json)["peerDependencies"]
+  peers_to_add = peers.reduce([]) do |result, (package, version)|
+    major_version = version.match(/(\d+)/)[1]
+    result << "#{package}@#{major_version}"
+  end.join(" ")
 
-  # needed for experimental Yarn 2 support and should not harm Yarn 1
-  say "Installing webpack and webpack-cli as direct dependencies"
-  results << run("yarn add webpack@#{webpack_version} webpack-cli@#{webpack_cli_version}")
+  say "Adding @rails/webpacker peerDependencies"
+  results << run("yarn add #{peers_to_add}")
 
-  say "Installing dev server for live reloading"
-  results << run("yarn add --dev webpack-dev-server @webpack-cli/serve")
+  say "Installing webpack-dev-server for live reloading as a development dependency"
+  results << run("yarn add --dev webpack-dev-server")
 end
 
 if Rails::VERSION::MAJOR == 5 && Rails::VERSION::MINOR > 1

package.json

@@ -11,32 +11,39 @@
     "node": ">= 12.13.0 || >=14",
     "yarn": ">=1 <4"
   },
-  "dependencies": {
+  "peerDependencies": {
     "@babel/core": "^7.15.5",
     "@babel/plugin-transform-runtime": "^7.15.0",
     "@babel/preset-env": "^7.15.6",
     "@babel/runtime": "^7.15.4",
     "babel-loader": "^8.2.2",
     "compression-webpack-plugin": "^9.0.0",
-    "glob": "^7.2.0",
-    "js-yaml": "^4.1.0",
-    "path-complete-extname": "^1.0.0",
     "pnp-webpack-plugin": "^1.7.0",
     "terser-webpack-plugin": "^5.2.4",
     "webpack": "^5.53.0",
     "webpack-assets-manifest": "^5.0.6",
     "webpack-cli": "^4.8.0",
-    "webpack-merge": "^5.8.0",
-    "webpack-sources": "^3.2.1"
+    "webpack-merge": "^5.8.0"
+  },
+  "dependencies": {
+    "glob": "^7.2.0",
+    "js-yaml": "^4.1.0",
+    "path-complete-extname": "^1.0.0"
   },
   "devDependencies": {
+    "babel-loader": "^8.2.2",
+    "compression-webpack-plugin": "^9.0.0",
     "eslint": "^7.32.0",
     "eslint-config-airbnb": "^18.2.1",
     "eslint-config-prettier": "^8.3.0",
     "eslint-plugin-import": "^2.24.2",
     "eslint-plugin-jsx-a11y": "^6.4.1",
     "eslint-plugin-react": "^7.26.0",
-    "jest": "^27.2.1"
+    "jest": "^27.2.1",
+    "pnp-webpack-plugin": "^1.7.0",
+    "webpack": "^5.53.0",
+    "webpack-assets-manifest": "^5.0.6",
+    "webpack-merge": "^5.8.0"
   },
   "jest": {
     "testRegex": "(/__tests__/.*|(\\.|/))\\.jsx?$",