I hate this shit so bad. Apparently, I was still under the impression that I was clever when these tests were written. All of this needs moved to simple test/unit + assert style but I don't have time right now so bacon is going to have to do. This should at least let us run the testsuite under Ruby 1.9.2 which is currently blocking all kinds of progress.
To use GAE's memcache with rack-cache, set the :metastore and :entitystore options as follows: use Rack::Cache, :metastore => 'gae://cache-meta', :entitystore => 'gae://cache-body' The 'cache-meta' and 'cache-body' parts are memcache namespace prefixes and should be set to different values.
You can specify an alternative cache key generator that is either a class that responds to .call() or is just a simple block. Also added the ability to set blocks as options in the configuration language.