This code does not work the same way as it did in 2.x:
render :partial => "things", :object => ['foo', 'bar', 'baz']
In 2.x, the "things" partial would be rendered once with a local variable called "things" storing the given array.
In 3.0.0 (and edge), the Action View assumes that you really meant :collection => ['foo', 'bar', 'baz'], so it iterates through the array and renders the partial once with each element. It will do this for any object which responds to to_ary.
I really think this is a case of Rails being too clever for its own good. The difference in behaviour between the :object and :collection options is large enough that this makes for a big break in expectations. If someone wants the :collection behaviour, they should use :collection.
(FWIW, an easy workaround is to pass the array into :locals, which people should probably be doing for arrays 99% of the time anyway, but silently assuming they meant :collection is not the way to encourage that behaviour.)
The relevant change to the code is more than a year old now (commit d0301e1) but I couldn't find any discussion about the change and the tests don't seem to assert anything about it either way. If it's really the behaviour we want, then it should be tested and documented. I can make a patch in either case.
-James
