fix: Gotcha with validation order (#50)

lib/has_state_machine/state.rb

@@ -20,11 +20,6 @@ class State < String
     # transactional? - Determines whether or not the transition should happen with a transactional block.
     delegate :possible_transitions, :transactional?, :state, to: "self.class"
 
-    ##
-    # Add errors to the ActiveRecord object rather than the HasStateMachine::State
-    # class.
-    delegate :errors, to: :object
-
     ##
     # Initializes the HasStateMachine::State instance.
     #

lib/has_state_machine/state_helpers.rb

@@ -114,7 +114,12 @@ def state_class_defined?
       def state_instance_validations
         return unless state_class.present?
 
-        public_send(state_attribute.to_s).valid?
+        state_instance = public_send(state_attribute.to_s)
+        return if state_instance.valid?
+
+        state_instance.errors.each do |error|
+          errors.add(error.attribute, error.type)
+        end
       end
     end
 

test/has_state_machine/state_helpers_test.rb

@@ -11,6 +11,10 @@
   t.string :status
 end
 
+ActiveRecord::Migration.create_table :animals, force: true do |t|
+  t.string :status
+end
+
 class Mountain < ActiveRecord::Base
   has_state_machine states: %i[foo bar baz]
   has_many :trees
@@ -21,6 +25,16 @@ class Tree < ActiveRecord::Base
   belongs_to :mountain
 end
 
+class Animal < ActiveRecord::Base
+  validate :failing_validation
+
+  has_state_machine states: %i[foo bar baz]
+
+  def failing_validation
+    errors.add(:fail, "animal is not valid")
+  end
+end
+
 module Workflow
   module Mountain
     class Foo < HasStateMachine::State
@@ -39,6 +53,16 @@ module Tree
     class Foo < HasStateMachine::State
     end
   end
+
+  module Animal
+    class Baz < HasStateMachine::State
+      validate :failing_validation
+
+      def failing_validation
+        errors.add(:base, "dummy validation failed")
+      end
+    end
+  end
 end
 
 class HasStateMachine::StateHelpersTest < ActiveSupport::TestCase
@@ -82,6 +106,17 @@ class HasStateMachine::StateHelpersTest < ActiveSupport::TestCase
 
       assert subject.valid?
     end
+
+    describe "object also contains errors" do
+      subject { Animal.new }
+
+      it "does not remove already existing errors from the object if state also has errors" do
+        subject.status = "baz"
+        refute subject.valid?
+
+        assert subject.errors.to_a.length == 2
+      end
+    end
   end
 
   describe "state attribute method" do

test/has_state_machine/state_test.rb

@@ -79,14 +79,6 @@ class HasStateMachine::StateTest < ActiveSupport::TestCase
     it { assert_equal %w[swimming floating tanning tubing lotioning], subject.possible_transitions }
   end
 
-  describe "#errors" do
-    it "delegates to the object" do
-      object.errors.add(:base, "foobar")
-
-      assert_equal({base: %w[foobar]}, subject.errors.messages)
-    end
-  end
-
   describe "#transition_to" do
     describe "callbacks" do
       it "runs before_transition callbacks" do