1 files changed, 17 insertions, 0 deletions
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