How to get FakeFS and VCR to play nice.

error.log

DONE Configuring VCR in Rspec for FakeFS
  Loaded fakefs/spec_helpers

ArgumentError: There is already a cassette with the same name (VCR example group metadata/records an http request).  You cannot nest multiple cassettes with the same name.
/src/cio/vendor/ruby/1.9.1/gems/vcr-2.3.0/lib/vcr.rb:116:in `insert_cassette'
/src/cio/vendor/ruby/1.9.1/gems/vcr-2.3.0/lib/vcr.rb:166:in `use_cassette'
/src/cio/vendor/ruby/1.9.1/gems/vcr-2.3.0/lib/vcr/test_frameworks/rspec.rb:83:in `block (2 levels) in configure!'
/src/cio/vendor/ruby/1.9.1/gems/rspec-core-2.12.1/lib/rspec/core/extensions/instance_eval_with_args.rb:16:in `instance_exec'
/src/cio/vendor/ruby/1.9.1/gems/rspec-core-2.12.1/lib/rspec/core/extensions/instance_eval_with_args.rb:16:in `instance_eval_with_args'
/src/cio/vendor/ruby/1.9.1/gems/rspec-core-2.12.1/lib/rspec/core/example.rb:247:in `instance_eval_with_args'
/src/cio/vendor/ruby/1.9.1/gems/rspec-core-2.12.1/lib/rspec/core/hooks.rb:93:in `block (2 levels) in run'
/src/cio/vendor/ruby/1.9.1/gems/vcr-2.3.0/lib/vcr/util/variable_args_block_caller.rb:9:in `call'
/src/cio/vendor/ruby/1.9.1/gems/vcr-2.3.0/lib/vcr/util/variable_args_block_caller.rb:9:in `call_block'
/src/cio/vendor/ruby/1.9.1/gems/vcr-2.3.0/lib/vcr.rb:169:in `use_cassette'
/src/cio/vendor/ruby/1.9.1/gems/vcr-2.3.0/lib/vcr/test_frameworks/rspec.rb:83:in `block (2 levels) in configure!'
/src/cio/vendor/ruby/1.9.1/gems/rspec-core-2.12.1/lib/rspec/core/extensions/instance_eval_with_args.rb:16:in `instance_exec'
/src/cio/vendor/ruby/1.9.1/gems/rspec-core-2.12.1/lib/rspec/core/extensions/instance_eval_with_args.rb:16:in `instance_eval_with_args'
/src/cio/vendor/ruby/1.9.1/gems/rspec-core-2.12.1/lib/rspec/core/example.rb:247:in `instance_eval_with_args'
/src/cio/vendor/ruby/1.9.1/gems/rspec-core-2.12.1/lib/rspec/core/hooks.rb:93:in `block (2 levels) in run'
/src/cio/vendor/ruby/1.9.1/gems/rspec-core-2.12.1/lib/rspec/core/hooks.rb:91:in `call'
/src/cio/vendor/ruby/1.9.1/gems/rspec-core-2.12.1/lib/rspec/core/hooks.rb:91:in `run'
/src/cio/vendor/ruby/1.9.1/gems/rspec-core-2.12.1/lib/rspec/core/hooks.rb:424:in `run_hook'
/src/cio/vendor/ruby/1.9.1/gems/rspec-core-2.12.1/lib/rspec/core/example_group.rb:327:in `run_around_each_hooks'
/src/cio/vendor/ruby/1.9.1/gems/rspec-core-2.12.1/lib/rspec/core/example.rb:256:in `with_around_each_hooks'
/src/cio/vendor/ruby/1.9.1/gems/rspec-core-2.12.1/lib/rspec/core/example.rb:111:in `run'
/src/cio/vendor/ruby/1.9.1/gems/rspec-core-2.12.1/lib/rspec/core/example_group.rb:388:in `block in run_examples'
/src/cio/vendor/ruby/1.9.1/gems/rspec-core-2.12.1/lib/rspec/core/example_group.rb:384:in `map'
/src/cio/vendor/ruby/1.9.1/gems/rspec-core-2.12.1/lib/rspec/core/example_group.rb:384:in `run_examples'
/src/cio/vendor/ruby/1.9.1/gems/rspec-core-2.12.1/lib/rspec/core/example_group.rb:369:in `run'
/src/cio/vendor/ruby/1.9.1/gems/rspec-core-2.12.1/lib/rspec/core/command_line.rb:28:in `block (2 levels) in run'
/src/cio/vendor/ruby/1.9.1/gems/rspec-core-2.12.1/lib/rspec/core/command_line.rb:28:in `map'
/src/cio/vendor/ruby/1.9.1/gems/rspec-core-2.12.1/lib/rspec/core/command_line.rb:28:in `block in run'
/src/cio/vendor/ruby/1.9.1/gems/rspec-core-2.12.1/lib/rspec/core/reporter.rb:34:in `report'
/src/cio/vendor/ruby/1.9.1/gems/rspec-core-2.12.1/lib/rspec/core/command_line.rb:25:in `run'
/src/cio/vendor/ruby/1.9.1/gems/rspec-core-2.12.1/lib/rspec/core/runner.rb:80:in `run'
/src/cio/vendor/ruby/1.9.1/gems/rspec-core-2.12.1/lib/rspec/core/runner.rb:17:in `block in autorun'

fakefs_persister.rb

require 'fileutils'

module Cio
  class Bdd
    # The only built-in cassette persister. Persists cassettes to the file system.
    class FakeFSFileSystem
        #extend self

        # @private
        attr_reader :storage_location

        def initialize(dir)
          @storage_location=dir
        end

        # @private
        def storage_location=(dir)
          puts 'is this called?'
          ::FakeFS.deactivate! if ::FakeFS.activated?
          ::FileUtils.mkdir_p(dir) if dir
          @storage_location = dir ? absolute_path_for(dir) : nil
          ::FakeFS.activate!
          @storage_location
        end

        # Gets the cassette for the given storage key (file name).
        #
        # @param [String] file_name the file name
        # @return [String] the cassette content
        def [](file_name)
          ::FakeFS.deactivate! if ::FakeFS.activated?
          path = absolute_path_to_file(file_name)
          return nil unless ::File.exist?(path)
          result = ::File.read(path)
          ::FakeFS.activate!
          result
        end

        # Sets the cassette for the given storage key (file name).
        #
        # @param [String] file_name the file name
        # @param [String] content the content to store
        def []=(file_name, content)
          ::FakeFS.deactivate! if ::FakeFS.activated?
          path = absolute_path_to_file(file_name)
          directory = File.dirname(path)
          FileUtils.mkdir_p(directory) unless File.exist?(directory)
          result = File.open(path, 'w') { |f| f.write(content) }
          ::FakeFS.activate!
          result
        end

        # @private
        def absolute_path_to_file(file_name)
          ::FakeFS.deactivate! if ::FakeFS.activated?
          return nil unless storage_location
          result = ::File.join(storage_location, sanitized_file_name_from(file_name))
          ::FakeFS.activate!
          result
        end

        private

        def absolute_path_for(path)
          ::FakeFS.deactivate! if ::FakeFS.activated?
          result = ::Dir.chdir(path) { ::Dir.pwd }
          ::FakeFS.activate!
          result
        end

        def sanitized_file_name_from(file_name)
          ::FakeFS.deactivate! if ::FakeFS.activated?
          parts = file_name.to_s.split('.')
          file_extension = '.' + parts.pop if parts.size > 1
          result = parts.join('.').gsub(/[^\w\-\/]+/, '_') + file_extension.to_s
          ::FakeFS.activate!
          result
        end
    end
  end
end

fakefs_vcr_spec.rb

require 'spec_helper'

def make_http_request(url)
  ::Typhoeus.get(url).body
end

def here(fname)
  RealFile.expand_path(File.join(RealFile.dirname(__FILE__), fname))
end

describe "VCR example group metadata",:vcr, :type => :fakefs do
  let(:url){'http://google.com.au/index.html'}
  it 'records an http request' do
    make_http_request(url).should match /The document has moved/
  end

  it 'records another http request' do
    make_http_request(url).should match /The document has moved/
  end

  context 'in a nested example group' do
    it 'records another one' do
      make_http_request(url).should match /The document has moved/
    end
  end
end

describe "VCR example metadata" do
  let(:url){'http://google.com/index.html'}
  it 'records an http request', :vcr do
    make_http_request(url).should match /The document has moved/
  end
end

spec_helper.rb

require 'fakeweb'
require 'typhoeus'
require 'vcr'

module ::FakeFSTrigger
  def self.included(base)
    RSpec.configure do |config|
      config.before(:suite) do
        require 'fakefs/spec_helpers'
        config.include ::FakeFS::SpecHelpers
        config.include ::Cio::Helpers::Shared # utility methods unique to BDD, but shared between rspec and cucumber
        config.include ::Cio::Spec::Support::Helpers::Include # utility methods unique to rspec
        config.extend ::Cio::Spec::Support::Helpers::Extend # utility methods unique to rspec
        ::FakeFS.activate!
        puts '  Loaded fakefs/spec_helpers'
      end
      config.after(:suite) do
        ::FakeFS::FileSystem.clear
        ::FakeFS.deactivate!
      end
    end
    VCR.configure do |c|
      begin
        require 'fakefs/spec_helpers'
        puts 'Configuring VCR in Rspec for FakeFS'
        c.allow_http_connections_when_no_cassette = true
        c.cassette_library_dir = 'bdd/cassettes'
        c.cassette_persisters[:file_system] = ::Cio::Bdd::FakeFSFileSystem.new('bdd/cassettes')
        c.default_cassette_options = { :persist_with => :file_system }
        c.hook_into :fakeweb, :typhoeus
        c.configure_rspec_metadata!
        c.ignore_localhost = true
        c.default_cassette_options = { :record => :new_episodes,
                                       :re_record_interval => 7.days }
        puts 'DONE Configuring VCR in Rspec for FakeFS'
      rescue => e
        puts e.message
        puts e.backtrace.join '\n'

      end
    end
  end
end

RSpec.configure do |c|
  # See http://rubydoc.info/gems/rspec-core/RSpec/Core/Configuration
  c.mock_with :rr #::RR::Adapters::Rspec
  c.backtrace_clean_patterns.push(::RR::Errors::BACKTRACE_IDENTIFIER)
  c.treat_symbols_as_metadata_keys_with_true_values = true
  c.run_all_when_everything_filtered = true
  c.filter_run :focus
  c.alias_it_should_behave_like_to :it_validates, "it validates"
  c.include ::FakeFSTrigger, :type => :fakefs
end