Only apply modules to highest level matching group

For the behaviour when apploying helper modules to existing example
groups to be fully consistent with the behaviour for new groups, we
shouldn't apply the module if any of the example group's parent groups
already have the module applied.

Also refactor how we add hooks to existing groups to use the same code.

Author: eugeneius

lib/rspec/core/configuration.rb

@@ -1749,7 +1749,8 @@ def before(scope=nil, *meta, &block)
         handle_suite_hook(scope, meta) do
           @before_suite_hooks << Hooks::BeforeHook.new(block, {})
         end || begin
-          add_hook_to_existing_groups(:append, :before, scope, *meta, &block)
+          metadata = Metadata.build_hash_from(meta.dup)
+          on_existing_matching_groups(metadata, scope) { |g| g.before(scope, *meta, &block) }
           super(scope, *meta, &block)
         end
       end
@@ -1772,7 +1773,8 @@ def prepend_before(scope=nil, *meta, &block)
         handle_suite_hook(scope, meta) do
           @before_suite_hooks.unshift Hooks::BeforeHook.new(block, {})
         end || begin
-          add_hook_to_existing_groups(:prepend, :before, scope, *meta, &block)
+          metadata = Metadata.build_hash_from(meta.dup)
+          on_existing_matching_groups(metadata, scope) { |g| g.prepend_before(scope, *meta, &block) }
           super(scope, *meta, &block)
         end
       end
@@ -1790,7 +1792,8 @@ def after(scope=nil, *meta, &block)
         handle_suite_hook(scope, meta) do
           @after_suite_hooks.unshift Hooks::AfterHook.new(block, {})
         end || begin
-          add_hook_to_existing_groups(:prepend, :after, scope, *meta, &block)
+          metadata = Metadata.build_hash_from(meta.dup)
+          on_existing_matching_groups(metadata, scope) { |g| g.after(scope, *meta, &block) }
           super(scope, *meta, &block)
         end
       end
@@ -1813,7 +1816,8 @@ def append_after(scope=nil, *meta, &block)
         handle_suite_hook(scope, meta) do
           @after_suite_hooks << Hooks::AfterHook.new(block, {})
         end || begin
-          add_hook_to_existing_groups(:append, :after, scope, *meta, &block)
+          metadata = Metadata.build_hash_from(meta.dup)
+          on_existing_matching_groups(metadata, scope) { |g| g.append_after(scope, *meta, &block) }
           super(scope, *meta, &block)
         end
       end
@@ -1822,7 +1826,8 @@ def append_after(scope=nil, *meta, &block)
       #
       # See {Hooks#around} for full `around` hook docs.
       def around(scope=nil, *meta, &block)
-        add_hook_to_existing_groups(:prepend, :around, scope, *meta, &block)
+        metadata = Metadata.build_hash_from(meta.dup)
+        on_existing_matching_groups(metadata, scope) { |g| g.around(scope, *meta, &block) }
         super(scope, *meta, &block)
       end
 
@@ -2026,15 +2031,18 @@ def configure_group_with(group, module_list, application_method)
         end
       end
 
-      def on_existing_matching_groups(meta)
-        world.all_example_groups.each do |group|
-          yield group if meta.empty? || MetadataFilter.apply?(:any?, meta, group.metadata)
-        end
-      end
+      def on_existing_matching_groups(meta, scope=:ignore)
+        groups = world.example_groups.dup
+
+        until groups.empty?
+          group = groups.shift
 
-      def add_hook_to_existing_groups(prepend_or_append, position, *meta, &block)
-        world.example_groups.each do |group|
-          group.hooks.register_global_hook(prepend_or_append, position, *meta, &block)
+          if scope == :example || scope == :each || scope.nil? ||
+              meta.empty? || MetadataFilter.apply?(:any?, meta, group.metadata)
+            yield group
+          else
+            groups.concat(group.children)
+          end
         end
       end
 

lib/rspec/core/hooks.rb

@@ -438,18 +438,6 @@ def register_global_singleton_context_hooks(example, globals)
           process(example, parent_groups, globals, :after,  :context) { {} }
         end
 
-        def register_global_hook(prepend_or_append, position, *args, &block)
-          scope, options = scope_and_options_from(*args)
-
-          if scope == :example || options.empty? || MetadataFilter.apply?(:all?, options, @owner.metadata)
-            register_hook(prepend_or_append, position, scope, options, &block)
-          else
-            @owner.children.each do |group|
-              group.hooks.register_global_hook(prepend_or_append, position, *args, &block)
-            end
-          end
-        end
-
         def register(prepend_or_append, position, *args, &block)
           scope, options = scope_and_options_from(*args)
 
@@ -463,7 +451,8 @@ def register(prepend_or_append, position, *args, &block)
             return
           end
 
-          register_hook(prepend_or_append, position, scope, options, &block)
+          hook = HOOK_TYPES[position][scope].new(block, options)
+          ensure_hooks_initialized_for(position, scope).__send__(prepend_or_append, hook, options)
         end
 
         # @private
@@ -564,11 +553,6 @@ def ensure_hooks_initialized_for(position, scope)
           end
         end
 
-        def register_hook(prepend_or_append, position, scope, options, &block)
-          hook = HOOK_TYPES[position][scope].new(block, options)
-          ensure_hooks_initialized_for(position, scope).__send__(prepend_or_append, hook, options)
-        end
-
         def process(host, parent_groups, globals, position, scope)
           hooks_to_process = globals.processable_hooks_for(position, scope, host)
           return if hooks_to_process.empty?