Add ActiveSupport::Cache::NullStore to expose caching interface without actually caching for development and test environments.

activerecord/CHANGELOG.md

@@ -146,6 +146,10 @@
     during :reject_if => :all_blank (fixes #2937)
 
     *Aaron Christy*
+    
+*   Add ActiveSupport::Cache::NullStore for use in development and testing.
+
+    *Brian Durand*
 
 ## Rails 3.1.3 (unreleased) ##
 

activesupport/lib/active_support/cache.rb

@@ -16,6 +16,7 @@ module ActiveSupport
     autoload :FileStore, 'active_support/cache/file_store'
     autoload :MemoryStore, 'active_support/cache/memory_store'
     autoload :MemCacheStore, 'active_support/cache/mem_cache_store'
+    autoload :NullStore, 'active_support/cache/null_store'
 
     # These options mean something to all cache implementations. Individual cache
     # implementations may support additional options.

activesupport/lib/active_support/cache/null_store.rb

@@ -0,0 +1,44 @@
+module ActiveSupport
+  module Cache
+    # A cache store implementation which doesn't actually store anything. Useful in
+    # development and test environments where you don't want caching turned on but
+    # need to go through the caching interface.
+    #
+    # This cache does implement the local cache strategy, so values will actually
+    # be cached inside blocks that utilize this strategy. See
+    # ActiveSupport::Cache::Strategy::LocalCache for more details.
+    class NullStore < Store
+      def initialize(options = nil)
+        super(options)
+        extend Strategy::LocalCache
+      end
+
+      def clear(options = nil)
+      end
+
+      def cleanup(options = nil)
+      end
+
+      def increment(name, amount = 1, options = nil)
+      end
+
+      def decrement(name, amount = 1, options = nil)
+      end
+
+      def delete_matched(matcher, options = nil)
+      end
+
+      protected
+        def read_entry(key, options) # :nodoc:
+        end
+
+        def write_entry(key, entry, options) # :nodoc:
+          true
+        end
+
+        def delete_entry(key, options) # :nodoc:
+          false
+        end
+    end
+  end
+end

activesupport/test/caching_test.rb

@@ -218,7 +218,7 @@ module CacheStoreBehavior
     @cache.write('fud', 'biz')
     assert_equal({"foo" => "bar", "fu" => "baz"}, @cache.read_multi('foo', 'fu'))
   end
-  
+
   def test_read_multi_with_expires
     @cache.write('foo', 'bar', :expires_in => 0.001)
     @cache.write('fu', 'baz')
@@ -576,12 +576,12 @@ class FileStoreTest < ActiveSupport::TestCase
     key = @cache_with_pathname.send(:key_file_path, "views/index?id=1")
     assert_equal "views/index?id=1", @cache_with_pathname.send(:file_path_key, key)
   end
-  
+
   # Because file systems have a maximum filename size, filenames > max size should be split in to directories
   # If filename is 'AAAAB', where max size is 4, the returned path should be AAAA/B
   def test_key_transformation_max_filename_size
     key = "#{'A' * ActiveSupport::Cache::FileStore::FILENAME_MAX_SIZE}B"
-    path = @cache.send(:key_file_path, key)    
+    path = @cache.send(:key_file_path, key)
     assert path.split('/').all? { |dir_name| dir_name.size <= ActiveSupport::Cache::FileStore::FILENAME_MAX_SIZE}
     assert_equal 'B', File.basename(path)
   end
@@ -689,14 +689,14 @@ uses_memcached 'memcached backed store' do
       cache.write("foo", 2)
       assert_equal "2", cache.read("foo")
     end
-    
+
     def test_raw_values_with_marshal
       cache = ActiveSupport::Cache.lookup_store(:mem_cache_store, :raw => true)
       cache.clear
       cache.write("foo", Marshal.dump([]))
-      assert_equal [], cache.read("foo")      
+      assert_equal [], cache.read("foo")
     end
-    
+
     def test_local_cache_raw_values
       cache = ActiveSupport::Cache.lookup_store(:mem_cache_store, :raw => true)
       cache.clear
@@ -717,6 +717,64 @@ uses_memcached 'memcached backed store' do
   end
 end
 
+class NullStoreTest < ActiveSupport::TestCase
+  def setup
+    @cache = ActiveSupport::Cache.lookup_store(:null_store)
+  end
+
+  def test_clear
+    @cache.clear
+  end
+
+  def test_cleanup
+    @cache.cleanup
+  end
+
+  def test_write
+    assert_equal true, @cache.write("name", "value")
+  end
+
+  def test_read
+    @cache.write("name", "value")
+    assert_nil @cache.read("name")
+  end
+
+  def test_delete
+    @cache.write("name", "value")
+    assert_equal false, @cache.delete("name")
+  end
+
+  def test_increment
+    @cache.write("name", 1, :raw => true)
+    assert_nil @cache.increment("name")
+  end
+
+  def test_decrement
+    @cache.write("name", 1, :raw => true)
+    assert_nil @cache.increment("name")
+  end
+
+  def test_delete_matched
+    @cache.write("name", "value")
+    @cache.delete_matched(/name/)
+  end
+
+  def test_local_store_strategy
+    @cache.with_local_cache do
+      @cache.write("name", "value")
+      assert_equal "value", @cache.read("name")
+      @cache.delete("name")
+      assert_nil @cache.read("name")
+      @cache.write("name", "value")
+    end
+    assert_nil @cache.read("name")
+  end
+
+  def test_setting_nil_cache_store
+    assert ActiveSupport::Cache.lookup_store.class.name, ActiveSupport::Cache::NullStore.name
+  end
+end
+
 class CacheStoreLoggerTest < ActiveSupport::TestCase
   def setup
     @cache = ActiveSupport::Cache.lookup_store(:memory_store)

railties/guides/source/caching_with_rails.textile

@@ -332,6 +332,14 @@ caches_action :index, :expires_in => 60.seconds, :unless_exist => true
 For more information about Ehcache, see "http://ehcache.org/":http://ehcache.org/ .
 For more information about Ehcache for JRuby and Rails, see "http://ehcache.org/documentation/jruby.html":http://ehcache.org/documentation/jruby.html
 
+h4. ActiveSupport::Cache::NullStore
+
+This cache store implementation is meant to be used only in development or test environments and it never stores anything. This can be very useful in development when you have code that interacts directly with +Rails.cache+, but caching may interfere with being able to see the results of code changes. With this cache store, all +fetch+ and +read+ operations will result in a miss.
+
+<ruby>
+ActionController::Base.cache_store = :null
+</ruby>
+
 h4. Custom Cache Stores
 
 You can create your own custom cache store by simply extending +ActiveSupport::Cache::Store+ and implementing the appropriate methods. In this way, you can swap in any number of caching technologies into your Rails application.

railties/test/application/middleware/cache_test.rb

@@ -54,9 +54,9 @@ module ApplicationTests
     def test_cache_keeps_if_modified_since
       simple_controller
       expected = "Wed, 30 May 1984 19:43:31 GMT"
-      
+
       get "/expires/keeps_if_modified_since", {}, "HTTP_IF_MODIFIED_SINCE" => expected
-      
+
       assert_equal 200, last_response.status
       assert_equal expected, last_response.body, "cache should have kept If-Modified-Since"
     end