Add symbol for getting local from #given

src/spectator/dsl/given_example_group_builder.cr

@@ -4,7 +4,7 @@ module Spectator
   module DSL
     class GivenExampleGroupBuilder < ExampleGroupBuilder
 
-      def initialize(what : String, @collection : Array(ValueWrapper))
+      def initialize(what : String, @collection : Array(ValueWrapper), @symbol : Symbol)
         super(what)
       end
 
@@ -12,7 +12,7 @@ module Spectator
         ExampleGroup.new(@what, parent).tap do |group|
           children = [] of ExampleGroup::Child
           @collection.each do |value|
-            iter_locals = locals.merge({:TODO => value})
+            iter_locals = locals.merge({@symbol => value})
             iter_children = @children.map do |child|
               child.build(group, iter_locals)
             end

src/spectator/dsl/structure_dsl.cr

@@ -59,7 +59,8 @@ module Spectator
 
           ::Spectator::DSL::Builder.start_given_group(
             {{collection.stringify}},
-            %to_a
+            %to_a,
+            :%group
           )
 
           {{block.body}}