Add mutation Hash#values_at -> Hash#fetch_values

Fixes #482

Changelog.md

@@ -3,6 +3,7 @@
 * Add mutation from `Hash#[]` to `Hash#key?` (#511)
 * Add mutation from `Hash#fetch` to `Hash#key?` (#511)
 * Add mutation from `#at` to `#key?` (#511)
+* Add mutation from `Hash#values_at` to `Hash#fetch_values` (#510)
 
 # v0.8.8 2015-xx-xx
 

lib/mutant/mutator/node/send.rb

@@ -28,6 +28,7 @@ module Mutant
           to_h:          %i[to_hash],
           at:            %i[fetch key?],
           fetch:         %i[key?],
+          values_at:     %i[fetch_values],
           :[] =>         %i[at fetch key?],
           :== =>         %i[eql? equal?],
           :>= =>         %i[> == eql? equal?],

meta/send.rb

@@ -223,6 +223,22 @@ Mutant::Meta::Example.add do
   mutation 'self.gsub(a, b)'
 end
 
+Mutant::Meta::Example.add do
+  source 'foo.values_at(a, b)'
+
+  singleton_mutations
+  mutation 'foo.fetch_values(a, b)'
+  mutation 'foo'
+  mutation 'self.values_at(a, b)'
+  mutation 'foo.values_at(a)'
+  mutation 'foo.values_at(b)'
+  mutation 'foo.values_at(nil, b)'
+  mutation 'foo.values_at(self, b)'
+  mutation 'foo.values_at(a, nil)'
+  mutation 'foo.values_at(a, self)'
+  mutation 'foo.values_at'
+end
+
 Mutant::Meta::Example.add do
   source 'foo.__send__(bar)'