Add undo integration spec

lib/undo/storage/rails_cache.rb

@@ -17,6 +17,7 @@ def store(uuid, object, options = {})
       end
 
       def fetch(uuid, options = {})
+        raise KeyError, "key #{uuid} not found" unless cache.exist? uuid
         unpack cache.read uuid, adapter_options(options)
       end
 

spec/undo/storage/rails_cache_integration_spec.rb

@@ -9,7 +9,7 @@
   it "deletes stored data" do
     subject.store 123, "hello" => "world"
     subject.delete 123
-    expect(subject.fetch 123).to be_nil
+    expect { subject.fetch 123 }.to raise_error(KeyError)
   end
 
   it "uses Rails.cache by default" do

spec/undo/storage/rails_cache_spec.rb

@@ -3,11 +3,7 @@
 
 describe Undo::Storage::RailsCache do
   subject { described_class.new cache }
-  let(:cache) { double :cache }
-
-  it "does not raise when created without arguments" do
-    expect { described_class.new }.not_to raise_error
-  end
+  let(:cache) { double :cache, exist?: true }
 
   it "uses provided cache storage" do
     subject = described_class.new cache
@@ -16,6 +12,10 @@
     subject.store "foo", "bar"
   end
 
+  it "does not raise when created without arguments" do
+    expect { described_class.new }.not_to raise_error
+  end
+
   describe "default options" do
     subject { described_class.new cache, options }
     let(:options) { { additional: :option } }

spec/undo/undo_integration_spec.rb

@@ -0,0 +1,10 @@
+require "spec_helper_rails"
+require_relative '../../../undo/integration/shared_undo_integration_examples.rb'
+
+Undo.configure do |config|
+  config.storage = Undo::Storage::RailsCache.new
+end
+
+describe Undo do
+  include_examples "undo integration"
+end