Multi fetch needs the array of keys splatted. (#29)

* Multi fetch needs the array of keys splatted.

* Fix tests to match rails multi_cache

Author: rovermicrover

lib/jsonapi/renderer/cached_resources_processor.rb

@@ -17,7 +17,7 @@ def initialize(cache)
       def process_resources
         [@primary, @included].each do |resources|
           cache_hash = cache_key_map(resources)
-          processed_resources = @cache.fetch_multi(cache_hash.keys) do |key|
+          processed_resources = @cache.fetch_multi(*cache_hash.keys) do |key|
             res, include, fields = cache_hash[key]
             json = res.as_jsonapi(include: include, fields: fields).to_json
 

spec/caching_spec.rb

@@ -5,7 +5,7 @@ def initialize
     @cache = {}
   end
 
-  def fetch_multi(keys)
+  def fetch_multi(*keys)
     keys.each_with_object({}) do |k, h|
       @cache[k] = yield(k) unless @cache.key?(k)
       h[k] = @cache[k]