Collections automatically cache and fetch partials.

Collections can take advantage of `multi_read` if they render one template
and their partials begin with a cache call.

The cache call must correspond to either what the collections elements are
rendered as, or match the inferred name of the partial.

So with a notifications/_notification.html.erb template like:

```ruby
<% cache notification %>
  <%# ... %>
<% end %>
```

A collection would be able to use `multi_read` if rendered like:

```ruby
<%= render @notifications %>
<%= render partial: 'notifications/notification', collection: @notifications, as: :notification %>
```

2 files changed, 6 insertions, 0 deletions

diff --git a/actionview/test/fixtures/test/_cached_customer.erb b/actionview/test/fixtures/test/_cached_customer.erb
new file mode 100644
index 0000000000..52f35a3497
--- /dev/null
+++ b/actionview/test/fixtures/test/_cached_customer.erb
@@ -0,0 +1,3 @@
+<% cache cached_customer do %>
+  Hello: <%= cached_customer.name %>
+<% end %>
\ No newline at end of file
diff --git a/actionview/test/fixtures/test/_cached_customer_as.erb b/actionview/test/fixtures/test/_cached_customer_as.erb
new file mode 100644
index 0000000000..fca8d19e34
--- /dev/null
+++ b/actionview/test/fixtures/test/_cached_customer_as.erb
@@ -0,0 +1,3 @@
+<% cache buyer do %>
+  <%= greeting %>: <%= customer.name %>
+<% end %>
\ No newline at end of file