Deal with circular relationship between world and config

lib/rspec/core.rb

@@ -83,7 +83,6 @@ def self.clear_examples
   def self.configuration
     @configuration ||= RSpec::Core::Configuration.new
   end
-  configuration.expose_dsl_globally = true
 
   # Yields the global configuration to a block.
   # @yield [Configuration] global configuration
@@ -178,4 +177,7 @@ def self.const_missing(name)
     require MODULES_TO_AUTOLOAD.fetch(name) { return super }
     ::RSpec.const_get(name)
   end
+
+  Core::DSL.expose_globally!
+  Core::SharedExampleGroup::TopLevelDSL.expose_globally!
 end

lib/rspec/core/configuration.rb

@@ -343,12 +343,13 @@ def treat_symbols_as_metadata_keys_with_true_values=(_value)
       # @private
       attr_writer :files_to_run
       # @private
-      attr_accessor :filter_manager
+      attr_accessor :filter_manager, :world
       # @private
       attr_accessor :static_config_filter_manager
       # @private
       attr_reader :backtrace_formatter, :ordering_manager, :loaded_spec_files
 
+      # rubocop:disable Metrics/AbcSize
       def initialize
         # rubocop:disable Style/GlobalVars
         @start_time = $_rspec_core_load_started_at || ::RSpec::Core::Time.now
@@ -394,9 +395,11 @@ def initialize
         @derived_metadata_blocks = FilterableItemRepository::QueryOptimized.new(:any?)
         @threadsafe = true
         @max_displayed_failure_line_count = 10
+        @world = World::Null
 
         define_built_in_hooks
       end
+      # rubocop:enable Metrics/AbcSize
 
       # @private
       #
@@ -1256,7 +1259,7 @@ def configure_group_with(group, module_list, application_method)
 
       # @private
       def configure_existing_groups(mod, meta, application_method)
-        RSpec.world.all_example_groups.each do |group|
+        world.all_example_groups.each do |group|
           next unless meta.empty? || MetadataFilter.apply?(:any?, meta, group.metadata)
           __send__(application_method, mod, group)
         end
@@ -1352,7 +1355,7 @@ def load_spec_files
         # in that case, the spec file was loaded by `ruby` and
         # isn't loaded by us here so we only know about it because
         # of an example group being registered in it.
-        RSpec.world.registered_example_group_files.each do |f|
+        world.registered_example_group_files.each do |f|
           loaded_spec_files << f # the registered files are already expended absolute paths
         end
 
@@ -1814,7 +1817,7 @@ def define_built_in_hooks
       end
 
       def assert_no_example_groups_defined(config_option)
-        return unless RSpec.world.example_groups.any?
+        return unless world.example_groups.any?
 
         raise MustBeConfiguredBeforeExampleGroupsError.new(
           "RSpec's #{config_option} configuration option must be configured before " \

lib/rspec/core/world.rb

@@ -12,6 +12,7 @@ class World
 
       def initialize(configuration=RSpec.configuration)
         @configuration = configuration
+        configuration.world = self
         @example_groups = []
         @example_group_counts_by_spec_file = Hash.new(0)
         @filtered_examples = Hash.new do |hash, group|
@@ -208,6 +209,24 @@ def fail_if_config_and_cli_options_invalid
           1 # exit code
         )
       end
+
+      # @private
+      # Provides a null implementation for initial use by configuration.
+      module Null
+        def self.registered_example_group_files
+          []
+        end
+
+        # :nocov:
+        def self.example_groups
+          []
+        end
+
+        def self.all_example_groups
+          []
+        end
+        # :nocov:
+      end
     end
   end
 end

spec/rspec/core/configuration_spec.rb

@@ -10,6 +10,8 @@ module RSpec::Core
     let(:exclusion_filter) { config.exclusion_filter.rules }
     let(:inclusion_filter) { config.inclusion_filter.rules }
 
+    before { config.world = RSpec.world }
+
     shared_examples_for "warning of deprecated `:example_group` during filtering configuration" do |method, *args|
       it "issues a deprecation warning when filtering by `:example_group`" do
         args << { :example_group => { :file_location => /spec\/unit/ } }