Refactor: always create module for shared example groups.

This simplifies things, makes things more consistent,
and prepares us to be able to better handle metadata
as per discussion in #1790.

Author: myronmarston

lib/rspec/core/configuration.rb

@@ -1219,8 +1219,8 @@ def include(mod, *filters)
       #
       # @see #include
       def include_context(shared_group_name, *filters)
-        block = world.shared_example_group_registry.find([:main], shared_group_name)
-        include SharedExampleGroupModule.new(shared_group_name, block), *filters
+        shared_module = world.shared_example_group_registry.find([:main], shared_group_name)
+        include shared_module, *filters
       end
 
       # Tells RSpec to extend example groups with `mod`. Methods defined in

lib/rspec/core/example_group.rb

@@ -364,16 +364,16 @@ def self.remove_example(example)
 
       # @private
       def self.find_and_eval_shared(label, name, inclusion_location, *args, &customization_block)
-        shared_block = RSpec.world.shared_example_group_registry.find(parent_groups, name)
+        shared_module = RSpec.world.shared_example_group_registry.find(parent_groups, name)
 
-        unless shared_block
+        unless shared_module
           raise ArgumentError, "Could not find shared #{label} #{name.inspect}"
         end
 
-        SharedExampleGroupInclusionStackFrame.with_frame(name, Metadata.relative_path(inclusion_location)) do
-          module_exec(*args, &shared_block)
-          module_exec(&customization_block) if customization_block
-        end
+        shared_module.include_in(
+          self, Metadata.relative_path(inclusion_location),
+          args, customization_block
+        )
       end
 
       # @!endgroup

lib/rspec/core/shared_example_group.rb

@@ -5,6 +5,9 @@ module Core
     # eval'd when the `SharedExampleGroupModule` instance is included in an example
     # group.
     class SharedExampleGroupModule < Module
+      # @private
+      attr_reader :definition
+
       def initialize(description, definition)
         @description = description
         @definition  = definition
@@ -21,8 +24,14 @@ def inspect
       # including example group.
       def included(klass)
         inclusion_line = klass.metadata[:location]
+        include_in klass, inclusion_line, [], nil
+      end
+
+      # @private
+      def include_in(klass, inclusion_line, args, customization_block)
         SharedExampleGroupInclusionStackFrame.with_frame(@description, inclusion_line) do
-          klass.class_exec(&@definition)
+          klass.class_exec(*args, &@definition)
+          klass.class_exec(&customization_block) if customization_block
         end
       end
     end
@@ -142,16 +151,17 @@ def self.remove_globally!
       class Registry
         def add(context, name, *metadata_args, &block)
           ensure_block_has_source_location(block) { CallerFilter.first_non_rspec_line }
+          shared_module = SharedExampleGroupModule.new(name, block)
 
           if valid_name?(name)
             warn_if_key_taken context, name, block
-            shared_example_groups[context][name] = block
+            shared_example_groups[context][name] = shared_module
           else
             metadata_args.unshift name
           end
 
           return if metadata_args.empty?
-          RSpec.configuration.include SharedExampleGroupModule.new(name, block), *metadata_args
+          RSpec.configuration.include shared_module, *metadata_args
         end
 
         def find(lookup_contexts, name)
@@ -177,13 +187,13 @@ def valid_name?(candidate)
         end
 
         def warn_if_key_taken(context, key, new_block)
-          existing_block = shared_example_groups[context][key]
+          existing_module = shared_example_groups[context][key]
 
-          return unless existing_block
+          return unless existing_module
 
           RSpec.warn_with <<-WARNING.gsub(/^ +\|/, ''), :call_site => nil
             |WARNING: Shared example group '#{key}' has been previously defined at:
-            |  #{formatted_location existing_block}
+            |  #{formatted_location existing_module.definition}
             |...and you are now defining it at:
             |  #{formatted_location new_block}
             |The new definition will overwrite the original one.

spec/rspec/core/shared_example_group_spec.rb

@@ -44,6 +44,10 @@ module Core
             group.send(shared_method_name, *args, &block)
           end
 
+          def find_implementation_block(registry, scope, name)
+            registry.find([scope], name).definition
+          end
+
           it "is exposed to the global namespace when expose_dsl_globally is enabled" do
             in_sub_process do
               RSpec.configuration.expose_dsl_globally = true
@@ -98,7 +102,7 @@ module Core
               it "captures the given #{type} and block in the collection of shared example groups" do
                 implementation = lambda { }
                 define_shared_group(object, &implementation)
-                expect(registry.find([group], object)).to eq implementation
+                expect(find_implementation_block(registry, group, object)).to eq implementation
               end
             end
           end
@@ -120,7 +124,7 @@ module Core
             it "captures the given string and block in the World's collection of shared example groups" do
               implementation = lambda { }
               define_shared_group("name", :foo => :bar, &implementation)
-              expect(registry.find([group], "name")).to eq implementation
+              expect(find_implementation_block(registry, group, "name")).to eq implementation
             end
 
             it "delegates include on configuration" do