forgot the test, oops!

railties/test/generators/argv_scrubber_test.rb

@@ -0,0 +1,36 @@
+require 'active_support/test_case'
+require 'active_support/testing/autorun'
+require 'rails/generators/rails/app/app_generator'
+
+module Rails
+  module Generators
+    class ARGVScrubberTest < ActiveSupport::TestCase
+      def test_version
+        ['-v', '--version'].each do |str|
+          scrubber = ARGVScrubber.new [str]
+          output    = nil
+          exit_code = nil
+          scrubber.extend(Module.new {
+            define_method(:puts) { |str| output = str }
+            define_method(:exit) { |code| exit_code = code }
+          })
+          scrubber.prepare
+          assert_equal "Rails #{Rails::VERSION::STRING}", output
+          assert_equal 0, exit_code
+        end
+      end
+
+      def test_prepare_returns_args
+        scrubber = ARGVScrubber.new ['hi mom']
+        args = scrubber.prepare
+        assert_equal '--help', args.first
+      end
+
+      def test_no_mutations
+        scrubber = ARGVScrubber.new ['hi mom'].freeze
+        args = scrubber.prepare
+        assert_equal '--help', args.first
+      end
+    end
+  end
+end