Oh look, there's the ruby call I was looking for (exit!)

features/env.rb

@@ -1,35 +0,0 @@
-require 'cucumber/ast/step_invocation'
-
-module Cucumber
-  module Ast
-    class StepInvocation #:nodoc:
-      def invoke(step_mother, options)
-        find_step_match!(step_mother)
-        unless @skip_invoke || options[:dry_run] || @exception || @step_collection.exception
-          @skip_invoke = true
-          begin
-            @step_match.invoke(@multiline_arg)
-            step_mother.after_step
-            status!(:passed)
-          rescue Pending => e
-            failed(options, e, false)
-            status!(:pending)
-          rescue Undefined => e
-            failed(options, e, false)
-            status!(:undefined)
-          rescue Cucumber::Ast::Table::Different => e
-            @different_table = e.table
-            failed(options, e, false)
-            status!(:failed)
-          rescue SystemExit => e
-            raise
-          rescue Exception => e
-            failed(options, e, false)
-            status!(:failed)
-          end
-        end
-      end
-    end
-  end
-end
-

features/step_definitions/command_line_steps.rb

@@ -53,14 +53,14 @@ When /^I run in a separate process: compass ([^\s]+) ?(.+)?$/ do |command, args|
       open('/tmp/last_error.compass_test.txt', 'w') do |file|
         file.puts @stderr.string
       end
-      exit # This doesn't exit
+      exit!
     end
     # this command will run forever
     # we kill it with a HUP signal from the parent process.
     args = (args || '').split
     args << { :wait => 5 }
     compass command, *args
-    exit
+    exit!
   end
 end
 

test/rails_helper.rb

@@ -0,0 +1,40 @@
+module Compass
+  module RailsHelper
+    def generate_rails_app_directories(name)
+      Dir.mkdir name
+      Dir.mkdir File.join(name, "config")
+      Dir.mkdir File.join(name, "config", "initializers")
+    end
+
+    # Generate a rails application without polluting our current set of requires
+    # with the rails libraries. This will allow testing against multiple versions of rails
+    # by manipulating the load path.
+    def generate_rails_app(name)
+      if pid = fork
+        Process.wait(pid)
+        if $?.exitstatus == 2
+          raise LoadError, "Couldn't load rails"
+        elsif $?.exitstatus != 0
+          raise "Failed to generate rails application."
+        end
+      else
+        begin
+          require 'rails/version'
+          require 'rails_generator'
+          require 'rails_generator/scripts/generate'
+          Rails::Generator::Base.use_application_sources!
+          capture_output do
+            Rails::Generator::Base.logger = Rails::Generator::SimpleLogger.new $stdout
+            Rails::Generator::Scripts::Generate.new.run([name], :generator => 'app')
+          end
+        rescue LoadError
+          Kernel.exit(2)
+        rescue => e
+          $stderr.puts e
+          Kernel.exit!(1)
+        end
+        Kernel.exit!(0)
+      end
+    end
+  end
+end