Group builder needs "what" as first arg

src/spectator/dsl/builder.cr

@@ -3,7 +3,7 @@ module Spectator
     module Builder
       extend self
 
-      @group_stack = [::Spectator::DSL::ExampleGroupBuilder.new]
+      @group_stack = [::Spectator::DSL::ExampleGroupBuilder.new("ROOT")]
 
       private def current_group
         @group_stack.last

src/spectator/dsl/example_group_builder.cr

@@ -8,6 +8,9 @@ module Spectator
       @after_each_hooks = [] of ->
       @around_each_hooks = [] of Proc(Nil) ->
 
+      def initialize(@what : String)
+      end
+
       def add_child(child : ExampleFactory | ExampleGroupBuilder) : Nil
         @children << child
       end