Instead of modifying the environment, run bundle install in a new process

JRuby does not support setting/unsetting environment variables.

Thus, we will launch an entirely new process without the parents env when
we run `bundle install` inside the generated rails apps, forcing them to
use their own Gemfile, instead of the BUNDLE_GEMFILE setting from the main
gem codebase.

features/fixture_replacement_config.feature

@@ -7,11 +7,10 @@ Feature:
     And I cd to "testapp"
     And I add "factory_girl_rails" from this project as a dependency
     And I configure the database connection for the application
-    And I reset Bundler environment variable
 
   Scenario: Using Factory Girl and Factory Girl Rails with Test Unit generates a factory file and does not generate a fixture file
-    And I successfully run `bundle install`
-    And I successfully run `bundle exec rails generate model User name:string`
+    And I run `bundle install` with a clean environment
+    And I run `bundle exec rails generate model User name:string` with a clean environment
     Then the following files should exist:
       | test/factories/users.rb |
     And the following files should not exist:
@@ -19,9 +18,9 @@ Feature:
 
   Scenario: Using Factory Girl and Factory Girl Rails with RSpec should generate a factory file
     When I add "rspec-rails" as a dependency
-    And I successfully run `bundle install`
+    And I run `bundle install` with a clean environment
     Then the output should contain "rspec-rails"
-    And I successfully run `bundle exec rails generate model User name:string`
+    And I run `bundle exec rails generate model User name:string` with a clean environment
     Then the following files should exist:
       | spec/factories/users.rb |
     And the following files should not exist:
@@ -30,9 +29,9 @@ Feature:
   Scenario: Using Factory Girl and Factory Girl Rails does not override a manually-configured factories directory using RSpec
     When I add "rspec-rails" as a dependency
     And I configure the factories directory as "custom/dir"
-    And I successfully run `bundle install`
+    And I run `bundle install` with a clean environment
     Then the output should contain "rspec-rails"
-    And I successfully run `bundle exec rails generate model User name:string`
+    And I run `bundle exec rails generate model User name:string` with a clean environment
     Then the following files should not exist:
       | test/factories/users.rb |
       | spec/factories/users.rb |
@@ -41,8 +40,8 @@ Feature:
 
   Scenario: Using Factory Girl and Factory Girl Rails does not override a manually-configured factories directory using Test::Unit
     When I configure the factories directory as "custom/dir"
-    And I successfully run `bundle install`
-    And I successfully run `bundle exec rails generate model User name:string`
+    And I run `bundle install` with a clean environment
+    And I run `bundle exec rails generate model User name:string` with a clean environment
     Then the following files should not exist:
       | test/factories/users.rb |
       | spec/factories/users.rb |
@@ -52,9 +51,9 @@ Feature:
   Scenario: Using Factory Girl and Factory Girl Rails with MiniTest should generate a factory file
     When I add "minitest" as a dependency
     And I configure the testing framework to use MiniTest
-    And I successfully run `bundle install`
+    And I run `bundle install` with a clean environment
     Then the output should contain "minitest"
-    And I successfully run `bundle exec rails generate model User name:string`
+    And I run `bundle exec rails generate model User name:string` with a clean environment
     Then the following files should exist:
       | test/factories/users.rb |
     But the following files should not exist:
@@ -64,9 +63,9 @@ Feature:
     When I configure the factories directory as "custom/dir"
     And I add "minitest" as a dependency
     And I configure the testing framework to use MiniTest
-    And I successfully run `bundle install`
+    And I run `bundle install` with a clean environment
     Then the output should contain "minitest"
-    And I successfully run `bundle exec rails generate model User name:string`
+    And I run `bundle exec rails generate model User name:string` with a clean environment
     Then the following files should exist:
       | custom/dir/users.rb |
     But the following files should not exist:

features/generators.feature

@@ -8,22 +8,21 @@ Feature:
     And I cd to "testapp"
     And I add "factory_girl_rails" from this project as a dependency
 		And I configure the database connection for the application
-		And I reset Bundler environment variable
 
   Scenario: The factory_girl_rails generators create a factory file for each model that I generate
-    When I successfully run `bundle install`
-    And I successfully run `bundle exec rails generate model User name:string --fixture-replacement=factory_girl`
-    And I successfully run `bundle exec rails generate model Namespaced::User name:string --fixture-replacement=factory_girl`
+    When I run `bundle install` with a clean environment
+    And I run `bundle exec rails generate model User name:string --fixture-replacement=factory_girl` with a clean environment
+    And I run `bundle exec rails generate model Namespaced::User name:string --fixture-replacement=factory_girl` with a clean environment
     Then the output should contain "test/factories/users.rb"
     And the output should contain "test/factories/namespaced_users.rb"
     And the file "test/factories/users.rb" should contain "factory :user do"
     And the file "test/factories/namespaced_users.rb" should contain "factory :namespaced_user, :class => 'Namespaced::User' do"
 
   Scenario: The factory_girl_rails generators create a factory file with a custom name for each model that I generate
-    When I successfully run `bundle install`
+    When I run `bundle install` with a clean environment
     And I set the FactoryGirl :suffix option to "factory"
-    And I successfully run `bundle exec rails generate model User name:string --fixture-replacement=factory_girl`
-    And I successfully run `bundle exec rails generate model Namespaced::User name:string --fixture-replacement=factory_girl`
+    And I run `bundle exec rails generate model User name:string --fixture-replacement=factory_girl` with a clean environment
+    And I run `bundle exec rails generate model Namespaced::User name:string --fixture-replacement=factory_girl` with a clean environment
     Then the output should contain "test/factories/users_factory.rb"
     And the output should contain "test/factories/namespaced_users_factory.rb"
     And the file "test/factories/users_factory.rb" should contain "factory :user do"

features/load_definitions.feature

@@ -5,9 +5,8 @@ Feature: automatically load step definitions
     And I cd to "testapp"
     And I add "factory_girl_rails" from this project as a dependency
     And I configure the database connection for the application
-    And I reset Bundler environment variable
     And I comment out gem "turn" from my Gemfile
-    When I successfully run `bundle install`
+    And I run `bundle install` with a clean environment
     And I write to "db/migrate/1_create_users.rb" with:
       """
       class CreateUsers < ActiveRecord::Migration
@@ -18,7 +17,7 @@ Feature: automatically load step definitions
         end
       end
       """
-    When I successfully run `bundle exec rake db:migrate --trace`
+    When I run `bundle exec rake db:migrate --trace` with a clean environment
     And I write to "app/models/user.rb" with:
       """
       class User < ActiveRecord::Base
@@ -45,7 +44,7 @@ Feature: automatically load step definitions
         end
       end
       """
-    When I successfully run `bundle exec rake test --trace`
+    When I run `bundle exec rake test --trace` with a clean environment
     Then the output should contain "1 tests, 1 assertions, 0 failures, 0 errors"
 
   Scenario: use factories advertised by railties/engines/3rd-party gems
@@ -83,5 +82,5 @@ Feature: automatically load step definitions
         end
       end
       """
-    When I successfully run `bundle exec rake test --trace`
+    When I run `bundle exec rake test --trace` with a clean environment
     Then the output should contain "1 tests, 1 assertions, 0 failures, 0 errors"

features/step_definitions/appraisal.rb

@@ -1,3 +1,5 @@
-When /^I reset Bundler environment variable$/ do
-  unset_bundler_env_vars
+When /^I run `([^"]+)` with a clean environment$/ do |command|
+  step %{I successfully run `ruby -e 'system({"BUNDLE_GEMFILE" => nil}, "#{command}")'`}
 end
+
+# system({'BUNDLE_GEMFILE' => nil}, "cd tmp/aruba/testapp && #{command} && cd -")

features/step_definitions/rails_steps.rb

@@ -31,7 +31,7 @@ end
 
 When /^I configure the testing framework to use MiniTest$/ do
   append_to_file('Gemfile', %{gem "minitest-rails", :group => [:development, :test]\n})
-  step %{I successfully run `rails generate mini_test:install`}
+  step %{I run `rails generate mini_test:install` with a clean environment}
 
   append_to_file File.join('config', 'application.rb'), <<-END
 class Testapp::Application