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, 16 insertions, 2 deletions

diff --git a/actionpack/test/template/digestor_test.rb b/actionpack/test/template/digestor_test.rb
index 02b1fd87a8..849e2981a6 100644
--- a/actionpack/test/template/digestor_test.rb
+++ b/actionpack/test/template/digestor_test.rb
@@ -138,6 +138,20 @@ class TemplateDigestorTest < ActionView::TestCase
     end
   end
 
+  def test_dependencies_via_options_results_in_different_digest
+    digest_plain        = digest("comments/_comment")
+    digest_fridge       = digest("comments/_comment", dependencies: ["fridge"])
+    digest_phone        = digest("comments/_comment", dependencies: ["phone"])
+    digest_fridge_phone = digest("comments/_comment", dependencies: ["fridge", "phone"])
+
+    assert_not_equal digest_plain, digest_fridge
+    assert_not_equal digest_plain, digest_phone
+    assert_not_equal digest_plain, digest_fridge_phone
+    assert_not_equal digest_fridge, digest_phone
+    assert_not_equal digest_fridge, digest_fridge_phone
+    assert_not_equal digest_phone, digest_fridge_phone
+  end
+
   private
     def assert_logged(message)
       old_logger = ActionView::Base.logger
@@ -164,8 +178,8 @@ class TemplateDigestorTest < ActionView::TestCase
       ActionView::Digestor.cache.clear
     end
 
-    def digest(template_name)
-      ActionView::Digestor.digest(template_name, :html, FixtureFinder.new)
+    def digest(template_name, options={})
+      ActionView::Digestor.digest(template_name, :html, FixtureFinder.new, options)
     end
 
     def change_template(template_name)