Install JavaScript packages before run test

Some tests are running yarn install during the test.
The directory used for isolation test is not subject to yarn workspace,
and it occurs because the required package is not installed.
In order to avoid this, I fixed all necessary packages to be installed
before run test and use symlink to `node_modules`.

This is a bit complicated, as `yarn install` needs to be run in a specific
directory before running the test.
However, running `yarn install` every time run the test is expensive
when testing locally and should be avoided.

6 files changed, 33 insertions, 11 deletions

diff --git a/railties/test/isolation/abstract_unit.rb b/railties/test/isolation/abstract_unit.rb
index ca7601f6fe..0e8e0e86ee 100644
--- a/railties/test/isolation/abstract_unit.rb
+++ b/railties/test/isolation/abstract_unit.rb
@@ -472,21 +472,17 @@ Module.new do
   FileUtils.rm_rf(app_template_path)
   FileUtils.mkdir_p(app_template_path)
 
-  Dir.chdir "#{RAILS_FRAMEWORK_ROOT}/actionview" do
-    `yarn build`
-  end
-
-  `#{Gem.ruby} #{RAILS_FRAMEWORK_ROOT}/railties/exe/rails new #{app_template_path} --skip-bundle --skip-listen --no-rc`
+  `#{Gem.ruby} #{RAILS_FRAMEWORK_ROOT}/railties/exe/rails new #{app_template_path} --skip-bundle --skip-listen --no-rc --skip-webpack-install`
   File.open("#{app_template_path}/config/boot.rb", "w") do |f|
     f.puts "require 'rails/all'"
   end
 
-  Dir.chdir(app_template_path) { `yarn add https://github.com/rails/webpacker.git` } # Use the latest version.
-
-  # Manually install `webpack` as bin symlinks are not created for sub dependencies
-  # in workspaces. See https://github.com/yarnpkg/yarn/issues/4964
-  Dir.chdir(app_template_path) { `yarn add webpack@4.17.1 --tilde` }
-  Dir.chdir(app_template_path) { `yarn add webpack-cli` }
+  assets_path = "#{RAILS_FRAMEWORK_ROOT}/railties/test/isolation/assets"
+  FileUtils.cp("#{assets_path}/package.json", "#{app_template_path}/package.json")
+  FileUtils.cp("#{assets_path}/config/webpacker.yml", "#{app_template_path}/config/webpacker.yml")
+  FileUtils.cp_r("#{assets_path}/config/webpack", "#{app_template_path}/config/webpack")
+  FileUtils.ln_s("#{assets_path}/node_modules", "#{app_template_path}/node_modules")
+  FileUtils.chdir(app_template_path) { `bin/rails webpacker:binstubs` }
 
   # Fake 'Bundler.require' -- we run using the repo's Gemfile, not an
   # app-specific one: we don't want to require every gem that lists.
diff --git a/railties/test/isolation/assets/config/webpack/development.js b/railties/test/isolation/assets/config/webpack/development.js
new file mode 100644
index 0000000000..395290f431
--- /dev/null
+++ b/railties/test/isolation/assets/config/webpack/development.js
@@ -0,0 +1,3 @@
+process.env.NODE_ENV = process.env.NODE_ENV || 'development'
+const { environment } = require('@rails/webpacker')
+module.exports = environment.toWebpackConfig()
diff --git a/railties/test/isolation/assets/config/webpack/production.js b/railties/test/isolation/assets/config/webpack/production.js
new file mode 100644
index 0000000000..d064a6a7fb
--- /dev/null
+++ b/railties/test/isolation/assets/config/webpack/production.js
@@ -0,0 +1,3 @@
+process.env.NODE_ENV = process.env.NODE_ENV || 'production'
+const { environment } = require('@rails/webpacker')
+module.exports = environment.toWebpackConfig()
diff --git a/railties/test/isolation/assets/config/webpack/test.js b/railties/test/isolation/assets/config/webpack/test.js
new file mode 100644
index 0000000000..395290f431
--- /dev/null
+++ b/railties/test/isolation/assets/config/webpack/test.js
@@ -0,0 +1,3 @@
+process.env.NODE_ENV = process.env.NODE_ENV || 'development'
+const { environment } = require('@rails/webpacker')
+module.exports = environment.toWebpackConfig()
diff --git a/railties/test/isolation/assets/config/webpacker.yml b/railties/test/isolation/assets/config/webpacker.yml
new file mode 100644
index 0000000000..0b1f43a407
--- /dev/null
+++ b/railties/test/isolation/assets/config/webpacker.yml
@@ -0,0 +1,8 @@
+default: &default
+  check_yarn_integrity: false
+development:
+  <<: *default
+test:
+  <<: *default
+production:
+  <<: *default
diff --git a/railties/test/isolation/assets/package.json b/railties/test/isolation/assets/package.json
new file mode 100644
index 0000000000..106b1029f0
--- /dev/null
+++ b/railties/test/isolation/assets/package.json
@@ -0,0 +1,9 @@
+{
+  "name": "dummy",
+  "private": true,
+  "dependencies": {
+    "@rails/ujs": "file:../../../../actionview",
+    "@rails/webpacker": "https://github.com/rails/webpacker.git",
+    "turbolinks": "^5.2.0"
+  }
+}