RSpec/NestedGroups Optimize #on_top_level_describe callback

lib/rubocop/cop/rspec/nested_groups.rb

@@ -98,6 +98,7 @@ class NestedGroups < Cop
           'deprecated in favor of `Max`. Please use that instead.'
 
         def_node_search :find_contexts, ExampleGroups::ALL.block_pattern
+        def_node_matcher :context?, ExampleGroups::ALL.block_pattern
 
         def on_top_level_describe(node, _args)
           find_nested_contexts(node.parent) do |context, nesting|
@@ -111,16 +112,19 @@ def on_top_level_describe(node, _args)
 
         private
 
-        def find_nested_contexts(node, nesting: 1, &block)
+        def find_nested_contexts(node)
           find_contexts(node) do |nested_context|
-            yield(nested_context, nesting) if nesting > max_nesting
+            nesting = context_nesting_count(nested_context)
 
-            nested_context.each_child_node do |child|
-              find_nested_contexts(child, nesting: nesting + 1, &block)
-            end
+            yield(nested_context, nesting) if nesting > max_nesting
           end
         end
 
+        def context_nesting_count(node)
+          parents = node.ancestors.select { |a| context?(a) }
+          parents.count + 1
+        end
+
         def message(nesting)
           format(MSG, total: nesting, max: max_nesting)
         end