Create a installation generator

[Heavily based on the ember.js bootstrap generator]

Running rails generate react:install will append the basic require directives
to application.js

Possible avenues for upgrades:

  - allow for files with arbitrary names ("mycomponents.js" instead of
    "application.js")

  - allow for files with different extensions ("application.js.coffee"
    instead of "application.js")

Author: xionon

lib/generators/react/install_generator.rb

@@ -0,0 +1,47 @@
+module React
+  module Generators
+    class InstallGenerator < ::Rails::Generators::Base
+      source_root File.expand_path '../../templates', __FILE__
+
+      desc 'Create default react.js folder layout and prep application.js'
+
+      class_option :skip_git,
+        type: :boolean,
+        aliases: '-g',
+        default: false,
+        desc: 'Skip Git keeps'
+
+      def create_directory
+        empty_directory 'app/assets/javascripts/components'
+        create_file 'app/assets/javascripts/components/.gitkeep' unless options[:skip_git]
+      end
+
+      def inject_react
+        require_react = "//= require react\n//= require react_ujs\n//= require components\n"
+
+        manifest = Pathname.new(destination_root).join('app/assets/javascripts',
+                                                       'application.js')
+
+        if manifest.exist?
+          manifest_contents = File.read(manifest)
+
+          if manifest_contents.include? 'require turbolinks'
+            inject_into_file manifest, require_react, {after: "//= require turbolinks\n"}
+          elsif manifest_contents.include? 'require_tree'
+            inject_into_file manifest, require_react, {before: '//= require_tree'}
+          else
+            append_file manifest, require_react
+          end
+        else
+          create_file manifest, require_react
+        end
+      end
+
+      def create_components
+        components_js = "//= require_tree ./components\n"
+        components_file = File.join(*%w(app assets javascripts components.js))
+        create_file components_file, components_js
+      end
+    end
+  end
+end

lib/generators/templates/.gitkeep

@@ -0,0 +1,50 @@
+require 'test_helper'
+require 'generators/react/install_generator'
+
+class InstallGeneratorTest < Rails::Generators::TestCase
+  destination File.join(Rails.root, 'tmp', 'generator_test_output')
+  tests React::Generators::InstallGenerator
+
+  def copy_directory(dir)
+    source = Rails.root.join(dir)
+    dest = Rails.root.join(destination_root, File.dirname(dir))
+
+    FileUtils.mkdir_p dest
+    FileUtils.cp_r source, dest
+  end
+
+  test "adds requires to `application.js`" do
+    run_generator
+
+    assert_application_file_modified
+  end
+
+  test "it modifes an existing 'application.js'" do
+    copy_directory('app/assets/javascripts/application.js')
+    run_generator
+    assert_application_file_modified
+  end
+
+  test "creates `application.js` if it doesn't exist" do
+    copy_directory('app/assets/javascripts/application.js')
+    File.delete destination_root + '/app/assets/javascripts/application.js'
+
+    run_generator
+
+    assert_application_file_modified
+  end
+
+  test "modifies `application.js` it's empty" do
+    File.write(destination_root + '/app/assets/javascripts/application.js', '')
+
+    run_generator
+
+    assert_application_file_modified
+  end
+
+  def assert_application_file_modified
+    assert_file 'app/assets/javascripts/application.js', %r{//= require react}
+    assert_file 'app/assets/javascripts/application.js', %r{//= require react_ujs}
+    assert_file 'app/assets/javascripts/application.js', %r{//= require components}
+  end
+end

test/generators/install_generator_test.rb

@@ -3,6 +3,7 @@
 
 require File.expand_path("../dummy/config/environment.rb",  __FILE__)
 require "rails/test_help"
+require "rails/generators"
 require "pathname"
 
 CACHE_PATH = Pathname.new File.expand_path("../dummy/tmp/cache",  __FILE__)