Extract rails gem loading into shared Gemfile.

When the example app is generated it puts a Rails version that is
defined by currently installed version. This works great in most
situtations, except `master` or other edge branches. The version listed
is the current version of Rails, so they diverge.

Move how we load rails into a custom Gemfile, which we eval ourselves.
We then remove the rails version put into the gemfile and share our
custom version. Due to when `rake` and other shell processes fork, the
RAILS_VERSION environment variable is properly passed through.

Author: cupakromer

Gemfile

@@ -36,25 +36,5 @@ end
 custom_gemfile = File.expand_path("../Gemfile-custom", __FILE__)
 eval_gemfile custom_gemfile if File.exist?(custom_gemfile)
 
-version_file = File.expand_path("../.rails-version", __FILE__)
-case version = ENV['RAILS_VERSION'] || (File.exist?(version_file) && File.read(version_file).chomp)
-when /master/
-  gem "rails", :git => "git://github.com/rails/rails.git"
-  gem "arel", :git => "git://github.com/rails/arel.git"
-  gem "journey", :git => "git://github.com/rails/journey.git"
-  gem "activerecord-deprecated_finders", :git => "git://github.com/rails/activerecord-deprecated_finders.git"
-  gem "rails-observers", :git => "git://github.com/rails/rails-observers"
-  gem 'sass-rails', :git => "git://github.com/rails/sass-rails.git"
-  gem 'coffee-rails', :git => "git://github.com/rails/coffee-rails.git"
-when /stable$/
-  gem "rails", :git => "git://github.com/rails/rails.git", :branch => version
-when nil, false, ""
-  if RUBY_VERSION < '1.9.3'
-    # Rails 4+ requires 1.9.3+, so on earlier versions default to the last 3.x release.
-    gem "rails", "~> 3.2.17"
-  else
-    gem "rails", "~> 4.0.4"
-  end
-else
-  gem "rails", version
-end
+rails_dependencies_gemfile = File.expand_path("../Gemfile-rails-dependencies", __FILE__)
+eval_gemfile rails_dependencies_gemfile

Gemfile-rails-dependencies

@@ -0,0 +1,22 @@
+version_file = File.expand_path("../.rails-version", __FILE__)
+case version = ENV['RAILS_VERSION'] || (File.exist?(version_file) && File.read(version_file).chomp)
+when /master/
+  gem "rails", :git => "git://github.com/rails/rails.git"
+  gem "arel", :git => "git://github.com/rails/arel.git"
+  gem "journey", :git => "git://github.com/rails/journey.git"
+  gem "activerecord-deprecated_finders", :git => "git://github.com/rails/activerecord-deprecated_finders.git"
+  gem "rails-observers", :git => "git://github.com/rails/rails-observers"
+  gem 'sass-rails', :git => "git://github.com/rails/sass-rails.git"
+  gem 'coffee-rails', :git => "git://github.com/rails/coffee-rails.git"
+when /stable$/
+  gem "rails", :git => "git://github.com/rails/rails.git", :branch => version
+when nil, false, ""
+  if RUBY_VERSION < '1.9.3'
+    # Rails 4+ requires 1.9.3+, so on earlier versions default to the last 3.x release.
+    gem "rails", "~> 3.2.17"
+  else
+    gem "rails", "~> 4.0.4"
+  end
+else
+  gem "rails", version
+end

templates/generate_app.rb

@@ -1,10 +1,17 @@
 rspec_rails_repo_path = File.expand_path("../../", __FILE__)
 rspec_dependencies_gemfile = File.join(rspec_rails_repo_path, 'Gemfile-rspec-dependencies')
+rails_dependencies_gemfile = File.join(rspec_rails_repo_path, 'Gemfile-rails-dependencies')
 in_root do
+  # Remove the existing rails version so we can properly use master or other
+  # edge branches
+  gsub_file 'Gemfile', /^.*\bgem 'rails.*$/, ''
+
+  # Use our version of RSpec and Rails
   append_to_file 'Gemfile', <<-EOT.gsub(/^ +\|/, '')
     |gem 'rspec-rails',
     |    :path => '#{rspec_rails_repo_path}',
     |    :groups => [:development, :test]
     |eval_gemfile '#{rspec_dependencies_gemfile}'
+    |eval_gemfile '#{rails_dependencies_gemfile}'
   EOT
 end