run.out

$ rspec xx_spec.rb 
....

Finished in 0.00287 seconds
4 examples, 0 failures

shared_spec.rb

# require 'spec_helper'
# require 'branch_cache'
# require 'changeset_cache'

# Fake out stuff I don'e have

require 'rspec/given'

CacheMissException = Class.new(StandardError)

class Cache
  def initialize
    @hash = {}
  end
  def store(key, data)
    @hash[key] = data
  end
  def fetch(key)
    @hash[key] or fail(CacheMissException)
  end
end
class BranchCache < Cache
end
class ChangesetCache < Cache
end

# Shared Examples

shared_examples "cached data" do
  Given(:cache) { described_class.new }

  context "can store and retreive changeset data by branch as a set" do
    Given(:data) { %w(data fake some) }
    When { cache.store("Big Branch", data) }
    Then { cache.fetch("Big Branch").sort.should eq(data) }
  end

  context "returns CacheMissException if lookup value with no data" do
    When(:result) { cache.fetch("Fake Branch") }
    Then { result.should have_failed(CacheMissException) }
  end
end

describe BranchCache do
  it_behaves_like "cached data"
end

describe ChangesetCache do
  it_behaves_like "cached data"
end

Ah, you're right. I had the block level of the describes wrong. Thanks for the quick check!