Ensure groups and examples are registered before invoking config definition hooks.

This is important so that if you load any support files that
define hooks from within a definition hook, it can apply the
hooks to the already-defined example groups (as is now
supported via #2189). Without this change, the current group
being defined is not eligible to have newly loaded hooks
applied to it.

Author: myronmarston

lib/rspec/core/dsl.rb

@@ -40,7 +40,9 @@ def self.expose_example_group_alias(name)
         example_group_aliases << name
 
         (class << RSpec; self; end).__send__(:define_method, name) do |*args, &example_group_block|
-          RSpec.world.register RSpec::Core::ExampleGroup.__send__(name, *args, &example_group_block)
+          group = RSpec::Core::ExampleGroup.__send__(name, *args, &example_group_block)
+          RSpec.world.record(group)
+          group
         end
 
         expose_example_group_alias_globally(name) if exposed_globally?

lib/rspec/core/example.rb

@@ -178,6 +178,8 @@ def initialize(example_group_class, description, user_metadata, example_block=ni
         @example_group_class = example_group_class
         @example_block       = example_block
 
+        example_group_class.examples << self
+
         @metadata = Metadata::ExampleHash.create(
           @example_group_class.metadata, user_metadata,
           example_group_class.method(:next_runnable_index_for),

lib/rspec/core/example_group.rb

@@ -143,9 +143,7 @@ def self.define_example_method(name, extra_options={})
           options.update(:skip => RSpec::Core::Pending::NOT_YET_IMPLEMENTED) unless block
           options.update(extra_options)
 
-          example = RSpec::Core::Example.new(self, desc, options, block)
-          examples << example
-          example
+          RSpec::Core::Example.new(self, desc, options, block)
         end
       end
 
@@ -235,27 +233,27 @@ def self.define_example_group_method(name, metadata={})
           thread_data = RSpec::Support.thread_local_data
           top_level   = self == ExampleGroup
 
-          if top_level
-            if thread_data[:in_example_group]
-              raise "Creating an isolated context from within a context is " \
-                    "not allowed. Change `RSpec.#{name}` to `#{name}` or " \
-                    "move this to a top-level scope."
+          registration_collection =
+            if top_level
+              if thread_data[:in_example_group]
+                raise "Creating an isolated context from within a context is " \
+                      "not allowed. Change `RSpec.#{name}` to `#{name}` or " \
+                      "move this to a top-level scope."
+              end
+
+              thread_data[:in_example_group] = true
+              RSpec.world.example_groups
+            else
+              children
             end
 
-            thread_data[:in_example_group] = true
-          end
-
           begin
-
             description = args.shift
             combined_metadata = metadata.dup
             combined_metadata.merge!(args.pop) if args.last.is_a? Hash
             args << combined_metadata
 
-            subclass(self, description, args, &example_group_block).tap do |child|
-              children << child
-            end
-
+            subclass(self, description, args, registration_collection, &example_group_block)
           ensure
             thread_data.delete(:in_example_group) if top_level
           end
@@ -379,9 +377,9 @@ def self.find_and_eval_shared(label, name, inclusion_location, *args, &customiza
       # @!endgroup
 
       # @private
-      def self.subclass(parent, description, args, &example_group_block)
+      def self.subclass(parent, description, args, registration_collection, &example_group_block)
         subclass = Class.new(parent)
-        subclass.set_it_up(description, *args, &example_group_block)
+        subclass.set_it_up(description, args, registration_collection, &example_group_block)
         subclass.module_exec(&example_group_block) if example_group_block
 
         # The LetDefinitions module must be included _after_ other modules
@@ -394,7 +392,7 @@ def self.subclass(parent, description, args, &example_group_block)
       end
 
       # @private
-      def self.set_it_up(description, *args, &example_group_block)
+      def self.set_it_up(description, args, registration_collection, &example_group_block)
         # Ruby 1.9 has a bug that can lead to infinite recursion and a
         # SystemStackError if you include a module in a superclass after
         # including it in a subclass: https://gist.github.com/845896
@@ -405,6 +403,8 @@ def self.set_it_up(description, *args, &example_group_block)
         # here.
         ensure_example_groups_are_configured
 
+        registration_collection << self
+
         user_metadata = Metadata.build_hash_from(args)
 
         @metadata = Metadata::ExampleGroupHash.create(
@@ -444,10 +444,10 @@ def self.children
       # @private
       def self.next_runnable_index_for(file)
         if self == ExampleGroup
-          RSpec.world.num_example_groups_defined_in(file)
+          RSpec.world.num_example_groups_defined_in(file) + 1
         else
           children.count + examples.count
-        end + 1
+        end
       end
 
       # @private

lib/rspec/core/world.rb

@@ -48,12 +48,10 @@ def registered_example_group_files
 
       # @api private
       #
-      # Register an example group.
-      def register(example_group)
+      # Records an example group.
+      def record(example_group)
         @configuration.on_example_group_definition_callbacks.each { |block| block.call(example_group) }
-        example_groups << example_group
         @example_group_counts_by_spec_file[example_group.metadata[:absolute_file_path]] += 1
-        example_group
       end
 
       # @private

spec/rspec/core/configuration_spec.rb

@@ -30,8 +30,7 @@ module RSpec::Core
       end
 
       it 'successfully invokes the block' do
-        example_group = RSpec.describe("group") { it "example 1" do; end}
-        RSpec.world.register(example_group)
+        RSpec.describe("group") { it "example 1" do; end}
         example = RSpec.world.example_groups.first.examples.first
         expect(example.metadata[:new_key]).to eq(:new_value)
       end
@@ -1501,6 +1500,50 @@ def exclude?(line)
         expect(example_bar_value).to eq("bar")
       end
 
+      it 'registers top-level groups before invoking the callback so the logic can configure already registered groups' do
+        registered_groups = nil
+
+        RSpec.configuration.define_derived_metadata do |_meta|
+          registered_groups = RSpec.world.example_groups
+        end
+
+        group = RSpec.describe("My group") do
+        end
+
+        expect(registered_groups).to eq [group]
+      end
+
+      it 'registers nested groups before invoking the callback so the logic can configure already registered groups' do
+        registered_groups = nil
+
+        RSpec.configuration.define_derived_metadata(:inner) do |_meta|
+          registered_groups = RSpec.world.all_example_groups
+        end
+
+        inner = nil
+        outer = RSpec.describe("Outer") do
+          inner = context "Inner", :inner do
+          end
+        end
+
+        expect(registered_groups).to contain_exactly(outer, inner)
+      end
+
+      it 'registers examples before invoking the callback so the logic can configure already registered groups' do
+        registered_examples = nil
+
+        RSpec.configuration.define_derived_metadata(:ex) do |_meta|
+          registered_examples = FlatMap.flat_map(RSpec.world.all_example_groups, &:examples)
+        end
+
+        example = nil
+        RSpec.describe("Outer") do
+          example = example("ex", :ex)
+        end
+
+        expect(registered_examples).to contain_exactly(example)
+      end
+
       context "when passed a metadata filter" do
         it 'only applies to the groups and examples that match that filter' do
           RSpec.configure do |c|

spec/rspec/core/world_spec.rb

@@ -18,7 +18,6 @@ module RSpec::Core
     describe "#example_groups" do
       it "contains all registered example groups" do
         example_group = RSpec.describe("group") {}
-        world.register(example_group)
         expect(world.example_groups).to include(example_group)
       end
     end
@@ -96,8 +95,6 @@ def preceding_declaration_line(line_num)
       end
 
       context "with one example" do
-        before { world.register(group) }
-
         it "returns nil if no example or group precedes the line" do
           expect(preceding_declaration_line(group_declaration_line - 1)).to be_nil
         end
@@ -123,8 +120,8 @@ def preceding_declaration_line(line_num)
         let(:second_group_declaration_line) { second_group.metadata[:line_number] }
 
         before do
-          world.register(second_group)
-          world.register(group)
+          world.record(second_group)
+          world.record(group)
         end
 
         it 'return line number of group if a group start on that line' do
@@ -146,8 +143,8 @@ def preceding_declaration_line(line_num)
         end
 
         before do
-          world.register(group)
-          world.register(group_from_another_file)
+          world.record(group)
+          world.record(group_from_another_file)
         end
 
         it "returns nil if given a file name with no declarations" do