Add hoc sequences in create_list

lib/factory_bot/strategy_syntax_method_registrar.rb

@@ -39,7 +39,7 @@ def define_list_strategy_method
 
         Array.new(amount) do |i|
           block_with_index = StrategySyntaxMethodRegistrar.with_index(block, i)
-          send(strategy_name, name, *traits_and_overrides, &block_with_index)
+          send(strategy_name, name, *evaluate_sequence_attributes(traits_and_overrides, i), &block_with_index)
         end
       end
     end

lib/factory_bot/syntax/methods.rb

@@ -129,6 +129,18 @@ def generate_list(name, count)
           Internal.sequence_by_name(name).next
         end
       end
+
+      def build_sequence(&block)
+        block
+      end
+
+      def evaluate_sequence_attributes(traits_and_overrides, i)
+        traits_and_overrides.map do |attribute|
+          next attribute unless attribute.is_a?(Hash)
+
+          attribute.transform_values { |value| value.respond_to?(:call) ? value.call(i) : value }
+        end    
+      end
     end
   end
 end

spec/acceptance/create_list_spec.rb

@@ -38,6 +38,16 @@
     end
   end
 
+  context "with sequencial attributes" do
+    subject { FactoryBot.create_list(:post, 20, title: FactoryBot.build_sequence{|n| "title_#{n}"}) }
+
+    it "create sequencial attribute values" do
+      subject.each_with_index do |record, i|
+        expect(record.title).to eq "title_#{i}"
+      end
+    end
+  end
+
   context "with a block" do
     subject do
       FactoryBot.create_list(:post, 20, title: "The Listing of the Block") do |post|