Fix document validations specs

app/models/document.rb

@@ -17,8 +17,8 @@ class Document < ActiveRecord::Base
   validate :validate_attachment_size,                 if: -> { attachment.present? }
   validates :title, presence: true
   validates :user_id, presence: true
-  # validates :documentable_id, presence: true
-  # validates :documentable_type, presence: true
+  validates :documentable_id, presence: true,         if: -> { persisted? }
+  validates :documentable_type, presence: true,       if: -> { persisted? }
 
   def validate_attachment_size
     if documentable.present? &&

spec/shared/models/document_validations.rb

@@ -46,12 +46,14 @@ shared_examples "document validations" do |documentable_factory|
   end
 
   it "should not be valid without a documentable_id" do
+    document.save
     document.documentable_id = nil
 
     expect(document).to_not be_valid
   end
 
   it "should not be valid without a documentable_type" do
+    document.save
     document.documentable_type = nil
 
     expect(document).to_not be_valid