[close #1202] Add support for Rails 7 & jsbundling (#1212)

* [close #1202] Add support for Rails 7 & jsbundling

Rails 7 introduced the gem:

```
gem "jsbundling-rails", "~> 0.1.0"
```

Which no longer relies on `webpacker`. 

Issue #1202 was opened since developers using jsbundling would expect `yarn` to be available but won't have the `webpacker` gem which we use to gate detection for yarn installation.

With this change we now install nodejs when a `package.json` is detected and yarn when `yarn.lock` is detected.

* [close #1202] Add support for Rails 7 & jsbundling

Rails 7 introduced the gem:

```
gem "jsbundling-rails", "~> 0.1.0"
```

Which no longer relies on `webpacker`. 

Issue #1202 was opened since developers using jsbundling would expect `yarn` to be available but won't have the `webpacker` gem which we use to gate detection for yarn installation.

With this change we now install nodejs when a `package.json` is detected and yarn when `yarn.lock` is detected.

.rspec

@@ -0,0 +1 @@
+--require dead_end

CHANGELOG.md

@@ -2,6 +2,9 @@
 
 ## Main (unreleased)
 
+* Applications with `package.json` now get `nodejs` installed (https://github.com/heroku/heroku-buildpack-ruby/pull/1212)
+* Applications with `yarn.lock` now get `yarn` installed (https://github.com/heroku/heroku-buildpack-ruby/pull/1212)
+
 ## v230 (10/5/2021)
 
 * Default Ruby version is now 2.7.4 (https://github.com/heroku/heroku-buildpack-ruby/pull/1193)

Gemfile

@@ -15,4 +15,5 @@ group :development, :test do
   gem 'json'
   gem 'ci-queue'
   gem 'redis'
+  gem 'dead_end'
 end

Gemfile.lock

@@ -3,6 +3,7 @@ GEM
   specs:
     ci-queue (0.21.0)
     citrus (3.0.2)
+    dead_end (2.0.0)
     diff-lcs (1.4.4)
     erubis (2.7.0)
     excon (0.85.0)
@@ -51,6 +52,7 @@ PLATFORMS
 
 DEPENDENCIES
   ci-queue
+  dead_end
   excon
   heroku_hatchet
   json

changelogs/unreleased/jsbundling_packagejson.md

@@ -0,0 +1,10 @@
+## Nodejs will now be installed for Ruby applications that have a `package.json` file
+
+Ruby applications using the `heroku/ruby` buildpack now receive a default version of `node` installed if they have a `package.json` file in the root directory of their application.
+
+Prior to this change, only applications using the `webpacker` or `execjs` gem would trigger node installation logic. This change is intended to facilitate Rails 7 applications using `jsbundling-rails` without `webpacker`.
+
+>Note
+>Applications using the `heroku/nodejs` buildpack before the `heroku/ruby` buildpack will not see a change in behavior
+
+For more information, see [Heroku Ruby support documentation](https://devcenter.heroku.com/articles/ruby-support#installed-binaries).

changelogs/unreleased/jsbundling_yarnlock.md

@@ -0,0 +1,10 @@
+## Yarn will now be installed for Ruby applications that have a `yarn.lock` file
+
+Ruby applications using the `heroku/ruby` buildpack now receive a default version of `yarn` installed if they have a `yarn.lock` file in the root directory of their application.
+
+Prior to this change, only applications using the `webpacker` gem would trigger node installation logic. This change is intended to facilitate Rails 7 applications using `jsbundling-rails` without `webpacker`.
+
+>Note
+>Applications using the `heroku/nodejs` buildpack before the `heroku/ruby` buildpack will not see a change in behavior
+
+For more information, see [Heroku Ruby support documentation](https://devcenter.heroku.com/articles/ruby-support#installed-binaries).

hatchet.json

@@ -48,7 +48,8 @@
     "sharpstone/active_storage_non_local",
     "sharpstone/active_storage_local",
     "sharpstone/sprockets_asset_compile_true",
-    "sharpstone/rails6-basic"
+    "sharpstone/rails6-basic",
+    "sharpstone/rails-jsbundling"
   ],
   "heroku": [
     "heroku/ruby-getting-started"

hatchet.lock

@@ -45,16 +45,14 @@
   - 18853ba7dda61745995740b4ca6f5f90bbd8afba
 - - "./repos/rails_versions/active_storage_non_local"
   - 86dddf0127043abba1cb2890590a1d38f111edbd
+- - "./repos/rails_versions/rails-jsbundling"
+  - 6b60a3aa7eb9507865ebba6afcca150017ab66b4
 - - "./repos/rails_versions/rails3_default_ruby"
   - a6b44db674c0d3538633989295e2cfd5e8e1ba0d
 - - "./repos/rails_versions/rails42_default_ruby"
   - dfa0f0133dafa62064968ea2efb6432f54350138
 - - "./repos/rails_versions/rails4_windows_mri193"
   - f4c7b6209835050468bbb87827acf652b8f4d8ce
-- - "./repos/rails_versions/rails5"
-  - 1680c5da829e03ffb9345187971a13e5109d86a6
-- - "./repos/rails_versions/rails51_webpacker"
-  - 75c5c4f21b1d88fc3b8edf60b3f871df3ad70208
 - - "./repos/rails_versions/rails6-basic"
   - 6b81e0246c64c332181c22ace4ac96b57309cb85
 - - "./repos/rails_versions/rails_lts_23_default_ruby"
@@ -69,8 +67,6 @@
   - ce976c727d9f477957c499f39f4cf9603c378103
 - - "./repos/rake/bad_rakefile"
   - 3cb9c7bf6494c59bd25fa74c2aa4531119e12a46
-- - "./repos/rake/connect_to_database_on_first_push"
-  - 635e002cb5a0400092dd5e80b88c6ffb740fda02
 - - "./repos/rake/default_with_rakefile"
   - c6e0c4db8dcccb47e11d496e17adbc2dafc80dd8
 - - "./repos/rake/no_rakefile"

lib/language_pack.rb

@@ -13,7 +13,7 @@ def self.detect(*args)
     Instrument.instrument 'detect' do
       Dir.chdir(args.first)
 
-      pack = [ NoLockfile, Rails6, Rails5, Rails42, Rails41, Rails4, Rails3, Rails2, Rack, Ruby ].detect do |klass|
+      pack = [ NoLockfile, Rails7, Rails6, Rails5, Rails42, Rails41, Rails4, Rails3, Rails2, Rack, Ruby ].detect do |klass|
         klass.use?
       end
 
@@ -50,4 +50,5 @@ def self.detect(*args)
 require "language_pack/rails42"
 require "language_pack/rails5"
 require "language_pack/rails6"
+require "language_pack/rails7"
 require "language_pack/no_lockfile"

lib/language_pack/rails6.rb

@@ -9,7 +9,7 @@ def self.use?
       rails_version = bundler.gem_version('railties')
       return false unless rails_version
       is_rails = rails_version >= Gem::Version.new('6.x') &&
-        rails_version < Gem::Version.new('7.0.0')
+        rails_version < Gem::Version.new('7.a')
       return is_rails
     end
   end

lib/language_pack/rails7.rb

@@ -0,0 +1,17 @@
+require 'securerandom'
+require "language_pack"
+require "language_pack/rails6"
+
+class LanguagePack::Rails7 < LanguagePack::Rails6
+  # @return [Boolean] true if it's a Rails 7.x app
+  def self.use?
+    instrument "rails6.use" do
+      rails_version = bundler.gem_version('railties')
+      return false unless rails_version
+      is_rails = rails_version >= Gem::Version.new('7.a') &&
+        rails_version < Gem::Version.new('8.0.0')
+      return is_rails
+    end
+  end
+end
+

lib/language_pack/ruby.rb

@@ -1053,15 +1053,25 @@ def pg_adapters
   # @note execjs will blow up if no JS RUNTIME is detected and is loaded.
   # @return [Array] the node.js binary path if we need it or an empty Array
   def add_node_js_binary
-    if (bundler.has_gem?('execjs') || bundler.has_gem?('webpacker')) && node_not_preinstalled?
+    return [] if node_js_preinstalled?
+
+    if Pathname(build_path).join("package.json").exist? ||
+         bundler.has_gem?('execjs') ||
+         bundler.has_gem?('webpacker')
       [@node_installer.binary_path]
     else
       []
     end
   end
 
   def add_yarn_binary
-    bundler.has_gem?('webpacker') && yarn_not_preinstalled? ? [@yarn_installer.name] : []
+    return [] if yarn_preinstalled?
+
+    if Pathname(build_path).join("yarn.lock").exist? || bundler.has_gem?('webpacker')
+      [@yarn_installer.name]
+    else
+      []
+    end
   end
 
   def has_yarn_binary?

spec/cnb/basic_local_pack_spec.rb

@@ -115,7 +115,7 @@ def run!(cmd)
       expect(app.output).to match("Compiling Ruby/Rails")
 
       run_out = app.run!("ruby -v")
-      expect(run_out).to match("2.6.6")
+      expect(run_out).to match("2.7.4")
     end
   end
 end

spec/hatchet/rails7_spec.rb

@@ -0,0 +1,19 @@
+require_relative '../spec_helper'
+
+describe "Rails 6" do
+  it "should detect successfully" do
+    Hatchet::App.new('rails-jsbundling').in_directory_fork do
+      expect(LanguagePack::Rails6.use?).to eq(false)
+      expect(LanguagePack::Rails7.use?).to eq(true)
+    end
+  end
+
+  it "works with jsbundling" do
+    Hatchet::Runner.new("rails-jsbundling").tap do |app|
+      app.deploy do
+        expect(app.output).to include("yarn install")
+        expect(app.output).to include("Asset precompilation completed")
+      end
+    end
+  end
+end