Add an extra layer to test passing down warn_about_add_children_to_leaf.

lib/i18n/tasks/data/tree/node.rb

@@ -10,12 +10,13 @@ class Node # rubocop:disable Metrics/ClassLength
     attr_accessor :value
     attr_reader :key, :children, :parent
 
-    def initialize(key:, value: nil, data: nil, parent: nil, children: nil)
+    def initialize(key:, value: nil, data: nil, parent: nil, children: nil, warn_about_add_children_to_leaf: true)
       @key = key
       @key = @key.to_s.freeze if @key
       @value = value
       @data = data
       @parent = parent
+      @warn_about_add_children_to_leaf = warn_about_add_children_to_leaf
       self.children = (children if children)
     end
 
@@ -34,7 +35,7 @@ def children=(children)
                   when NilClass
                     nil
                   else
-                    Siblings.new(nodes: children, parent: self)
+                    Siblings.new(nodes: children, parent: self, warn_about_add_children_to_leaf: @warn_about_add_children_to_leaf)
                   end
       dirty!
     end

lib/i18n/tasks/data/tree/siblings.rb

@@ -105,7 +105,7 @@ def set(full_key, node)
 
       if rest
         unless child
-          child = Node.new(key: key_part, parent: parent, children: [])
+          child = Node.new(key: key_part, parent: parent, children: [], warn_about_add_children_to_leaf: @warn_add_children_to_leaf)
           append! child
         end
         unless child.children

spec/used_keys_spec.rb

@@ -9,8 +9,8 @@
 div = t 'a'
   p = t 'a'
 h1 = t 'b'
-h2 = t 'c'
-h3 = t 'c.underneath_c'
+h2 = t 'c.layer'
+h3 = t 'c.layer.underneath_c'
     SLIM
   end