cannot run 'rake test' from jruby-complete.jar

Ok, now the obvious question I should have asked you first: have you tried against JRuby 1.5 dev snapshots?

Check out http://ci.jruby.org/snapshots

Yes - same error using jruby-complete-1.5.0.dev.jar

Could it be related to this: http://jira.codehaus.org/browse/JRUBY-4249

Will take a look. I was pretty sure that this is fixed on master branch, but maybe there is some other place that breaks for test, but works for spec.

OK, can reproduce the problem with the latest JRuby from master branch.

The problem is that Rake on Windows uses a rather weird way to launch ruby to execute tests, specifically: "call path_to_ruby ...". In this special case, when the first entry is 'call', JRuby's in-process launching magic doesn't work, since it works only when the first parameter is some kind of ruby, not 'call'.

Not sure how to proceed here. We probably could hack-up some solution to add 'call' case to in-process detection magic, but this feels really hacky solution... Any opinions?

Alternatively, one could submit some patch to Rake itself, but again, not clear what that could be. Running rake in such a weird envirenment like from within jruby-complete.jar on Windows won't probably be significant enough to change Rake...

The only workaround on Windows at the moment is to use proper JRuby, not jruby-complete.jar....

Special-casing "call" does seem pretty hacky. Is "call" a standard windows thing? I don't remember ever using it.

We don't have any patches for Rake at all right now...so I'd prefer we try to get this patched in Rake itself. I think Jim Weirich would be open to any fix that seems appropriate, but I have not looked closely enough at the problem to know what to suggest...

I think we need to involve the Rake folks on this. Rake needs a better way to launch whatever Ruby it's running in, probably by calling into a core method of some kind like Kernel.launch_ruby, which would allow us to do the right thing depending on how we're being run. This is a systemic problem with a lot of Ruby programs that launch "sub rubies", since they won't ever work with anything that isn't called "ruby" or doesn't have a normal executable on disk.

Homer: I'm bumping this off JRuby 1.5, since it's obviously not something we're going to be able to work out with the Rake guys. If you're really interested in making this work, we will help coordinate with the Rake folks on how to make this work. I have a picture in my head of how it should look, but we need someone like you to own the task of making this move forward.

Here's our 'patch' for this problem:

# put this in RAILS_ROOT/lib/rake/tasks or rakelib
$ cat lib/tasks/rake_patch.rake

# http://jira.codehaus.org/browse/JRUBY-4530
# when using jruby-complete.jar, FileUtils::RUBY is the <bindir inside the jar>/jruby.exe
# we 'fix' this by overwriting the path here
if defined?(JRUBY_VERSION)
  module FileUtils
    RUBY = "#{Rails.root}/jruby#{'.bat' if Config::CONFIG['host_os'] =~ /mswin/}"
  end
end

I believe this was fixed along with JRUBY-5576.