2 files changed, 22 insertions, 3 deletions
diff --git a/railties/lib/rails/generators/testing/assertions.rb b/railties/lib/rails/generators/testing/assertions.rb
index 6267b2f2ee..bd069e4bd0 100644
--- a/railties/lib/rails/generators/testing/assertions.rb
+++ b/railties/lib/rails/generators/testing/assertions.rb
@@ -1,3 +1,5 @@
+require 'shellwords'
+
 module Rails
   module Generators
     module Testing
@@ -21,8 +23,8 @@ module Rails
         #     end
         #   end
         def assert_file(relative, *contents)
-          absolute = File.expand_path(relative, destination_root)
-          assert File.exists?(absolute), "Expected file #{relative.inspect} to exist, but does not"
+          absolute = File.expand_path(relative, destination_root).shellescape
+          assert File.exist?(absolute), "Expected file #{relative.inspect} to exist, but does not"
 
           read = File.read(absolute) if block_given? || !contents.empty?
           yield read if block_given?
@@ -44,7 +46,7 @@ module Rails
         #   assert_no_file "config/random.rb"
         def assert_no_file(relative)
           absolute = File.expand_path(relative, destination_root)
-          assert !File.exists?(absolute), "Expected file #{relative.inspect} to not exist, but does"
+          assert !File.exist?(absolute), "Expected file #{relative.inspect} to not exist, but does"
         end
         alias :assert_no_directory :assert_no_file
 
diff --git a/railties/lib/rails/generators/testing/behaviour.rb b/railties/lib/rails/generators/testing/behaviour.rb
index 7576eba6e0..e0600d0b59 100644
--- a/railties/lib/rails/generators/testing/behaviour.rb
+++ b/railties/lib/rails/generators/testing/behaviour.rb
@@ -100,6 +100,23 @@ module Rails
             dirname, file_name = File.dirname(absolute), File.basename(absolute).sub(/\.rb$/, '')
             Dir.glob("#{dirname}/[0-9]*_*.rb").grep(/\d+_#{file_name}.rb$/).first
           end
+
+          def capture(stream)
+            stream = stream.to_s
+            captured_stream = Tempfile.new(stream)
+            stream_io = eval("$#{stream}")
+            origin_stream = stream_io.dup
+            stream_io.reopen(captured_stream)
+
+            yield
+
+            stream_io.rewind
+            return captured_stream.read
+          ensure
+            captured_stream.close
+            captured_stream.unlink
+            stream_io.reopen(origin_stream)
+          end
       end
     end
   end