view_cache_dependency API

A declarative API for specifying dependencies that affect template
cache digest computation. In your controller, specify any of said
dependencies:

  view_cache_dependency { "phone" if using_phone? }

When the block is evaluated, the resulting value is included in the
cache digest calculation, allowing you to generate different digests
for effectively the same template. (Mostly useful if you're mucking
with template load paths.)

1 files changed, 18 insertions, 0 deletions

diff --git a/actionpack/test/controller/caching_test.rb b/actionpack/test/controller/caching_test.rb
index 2428cd7433..eb5eeb0423 100644
--- a/actionpack/test/controller/caching_test.rb
+++ b/actionpack/test/controller/caching_test.rb
@@ -296,6 +296,24 @@ class CacheHelperOutputBufferTest < ActionController::TestCase
   end
 end
 
+class ViewCacheDependencyTest < ActionController::TestCase
+  class NoDependenciesController < ActionController::Base
+  end
+
+  class HasDependenciesController < ActionController::Base
+    view_cache_dependency { "trombone" }
+    view_cache_dependency { "flute" }
+  end
+
+  def test_view_cache_dependencies_are_empty_by_default
+    assert NoDependenciesController.view_cache_dependencies.empty?
+  end
+
+  def test_view_cache_dependencies_are_listed_in_declaration_order
+    assert_equal %w(trombone flute), HasDependenciesController.view_cache_dependencies
+  end
+end
+
 class DeprecatedPageCacheExtensionTest < ActiveSupport::TestCase
   def test_page_cache_extension_binds_default_static_extension
     deprecation_behavior = ActiveSupport::Deprecation.behavior