BUGFIX: Parent/Child implicit trait results depend on build order.

lib/factory_bot/definition.rb

@@ -95,6 +95,10 @@ def define_trait(trait)
       @defined_traits.add(trait)
     end
 
+    def defined_traits_names
+      @defined_traits.map(&:name)
+    end
+
     def register_enum(enum)
       @registered_enums << enum
     end

lib/factory_bot/factory.rb

@@ -17,7 +17,8 @@ def initialize(name, options = {})
     end
 
     delegate :add_callback, :declare_attribute, :to_create, :define_trait, :constructor,
-      :defined_traits, :inherit_traits, :append_traits, to: :@definition
+      :defined_traits, :defined_traits_names, :inherit_traits, :append_traits,
+      to: :@definition
 
     def build_class
       @build_class ||= if class_name.is_a? Class
@@ -85,7 +86,7 @@ def names
     def compile
       unless @compiled
         parent.compile
-        parent.defined_traits.each { |trait| define_trait(trait) }
+        inherit_parent_traits
         @definition.compile(build_class)
         build_hierarchy
         @compiled = true
@@ -153,6 +154,13 @@ def parent
       end
     end
 
+    def inherit_parent_traits
+      parent.defined_traits.each do |trait|
+        next if defined_traits_names.include?(trait.name)
+        define_trait(trait.clone)
+      end
+    end
+
     def initialize_copy(source)
       super
       @definition = @definition.clone

lib/factory_bot/trait.rb

@@ -14,6 +14,10 @@ def initialize(name, &block)
       end
     end
 
+    def clone
+      Trait.new(name, &block)
+    end
+
     delegate :add_callback, :declare_attribute, :to_create, :define_trait, :constructor,
       :callbacks, :attributes, :klass, :klass=, to: :@definition
 

spec/acceptance/traits_spec.rb

@@ -38,6 +38,10 @@
           gender { "Female" }
         end
 
+        trait :make_it_great do
+          great
+        end
+
         factory :great_user do
           great
         end
@@ -50,6 +54,12 @@
           end
         end
 
+        factory :greatest_user do
+          trait :great do
+            great { "GREATEST EVER!!!" }
+          end
+        end
+
         factory :admin, traits: [:admin]
 
         factory :male_user do
@@ -177,6 +187,24 @@
     end
   end
 
+  context "factory with implicit traits called by child" do
+    it "calls the correct trait when parent built first" do
+      user = FactoryBot.create(:user, :make_it_great)
+      # greatest = FactoryBot.create(:greatest_user, :make_it_great)
+
+      expect(user.great).to eq "GREAT!!!"
+      # expect(greatest.great).to eq "GREATEST EVER!!!"
+    end
+
+    it "calls the correct trait when child built first" do
+      greatest = FactoryBot.create(:greatest_user, :make_it_great)
+      user = FactoryBot.create(:user, :make_it_great)
+
+      expect(user.great).to eq "GREAT!!!"
+      expect(greatest.great).to eq "GREATEST EVER!!!"
+    end
+  end
+
   context "child factory created where trait attributes are inherited" do
     subject { FactoryBot.create(:child_male_user) }
     its(:gender) { should eq "Male" }