Only write to collection cache if we have a callable cache key.

A callable cache key writes to the collection cache under a certain namespace.
Which means if we don't have scoped cache key we can just rely on the
`cache model_name do` in the templates to cache them.

Less writes, more sharing.

Add `assert_customer_cached` to better illustrate this in tests, and remove
tests which then don't communicate as much.

1 files changed, 5 insertions, 1 deletions

diff --git a/actionview/lib/action_view/renderer/partial_renderer/collection_caching.rb b/actionview/lib/action_view/renderer/partial_renderer/collection_caching.rb
index 4bc4147e1b..c353eb0b31 100644
--- a/actionview/lib/action_view/renderer/partial_renderer/collection_caching.rb
+++ b/actionview/lib/action_view/renderer/partial_renderer/collection_caching.rb
@@ -51,10 +51,14 @@ module ActionView
       end
 
       def fetch_or_cache_partial(cached_partials, order_by:)
+        rely_on_individual_cache_call = !callable_cache_key?
+
         order_by.map do |key|
           cached_partials.fetch(key) do
             yield.tap do |rendered_partial|
-              collection_cache.write(key, rendered_partial, @options[:cache_options])
+              unless rely_on_individual_cache_call
+                collection_cache.write(key, rendered_partial, @options[:cache_options])
+              end
             end
           end
         end