add support for registering runners

[jrluis]

This runs cucumber tests mixed with rspec tests.

To add the cucumber plugin add rrrspec-cucumber to your gemfile

gem 'rrrspec-cucumber'

Then in .rrrspec configure the runner chain to include rrrspec-cucumber

require 'rrrspec/cucumber'

RRRSpec::Registry.register_runner RRRSpec::Cucumber::CucumberRunnerFactory.new, '.feature'

You can checkout the plugin code at https://github.com/Seedrs/rrrspec-cucumber

For the slave to load the .rrrspec configuration the slave command also has to be changed

  conf.slave_command = <<-SLAVE
    bundle exec rrrspec-client slave --config .rrrspec
  SLAVE

Finally, add cucumber to a rails project and in .rrrspec also select the .features

conf.spec_files = lambda do
    Dir.chdir(conf.packaging_dir) do
        Dir['features/**{,/*/**}/*.feature'].uniq
    end
end

[draftcode]

BUG: RSpecRunner has a before_suite_run flag for oneshot suite-wide initialization. New-ing the runner for each task resets this flag and causes multiple initialization.

[jrluis]

I've made a chain of runner factories, to allow plugin the runners.
The RSpecRunnerFactory has the runner as a singleton, that way the bug is gone. I've also added a spec to avoid this bug in the future.

[draftcode]

If the factory implementation can be switched by the file extension, isn't it better to have a registry type plugin structure instead of chaining?

[jrluis]

A registry would be a nice solution, but it would limit how the choice of the runner is made.

Currently the choice is made in the plugin, if we change it to a registry, the choice would be made be rrrspec and not in the plugin.

My doubt is if we can find a general rule that works for all future cases so that the choice can be made in rrrspec code and not in the plugin.

[draftcode]

I think it's really hard to find a "general rule" based on a file extension. It's just a few characters. If there's no usage for that flexibility right now, it's better to keep it simple. Chaining is a good solution if the argument needs to be decorated (e.g. Java's Servlet API), but in this case it seems no use to me. If you should need more flexibility, it's better to let users to specify the factory directly and let them write in a composition style, instead of forcing chaining.

[jrluis]

Added a registry for runner factories

[draftcode]

Please move this to rspec_runner_factory.rb

[jrluis]

done