add index_errors association matcher

lib/shoulda/matchers/active_record/association_matcher.rb

@@ -524,6 +524,25 @@ module Shoulda
       #       should have_many(:games).autosave(true)
       #     end
       #
+      # ##### index_errors
+      #
+      # Use `index_errors` to assert that the `:index_errors` option was
+      # specified.
+      #
+      #     class Player < ActiveRecord::Base
+      #       has_many :games, index_errors: true
+      #     end
+      #
+      #     # RSpec
+      #     RSpec.describe Player, type: :model do
+      #       it { should have_many(:games).index_errors(true) }
+      #     end
+      #
+      #     # Minitest (Shoulda)
+      #     class PlayerTest < ActiveSupport::TestCase
+      #       should have_many(:games).index_errors(true)
+      #     end
+      #
       # ##### inverse_of
       #
       # Use `inverse_of` to assert that the `:inverse_of` option was specified.
@@ -1022,6 +1041,11 @@ module Shoulda
           self
         end
 
+        def index_errors(index_errors)
+          @options[:index_errors] = index_errors
+          self
+        end
+
         def class_name(class_name)
           @options[:class_name] = class_name
           self
@@ -1096,6 +1120,7 @@ module Shoulda
             class_name_correct? &&
             join_table_correct? &&
             autosave_correct? &&
+            index_errors_correct? &&
             conditions_correct? &&
             validate_correct? &&
             touch_correct? &&
@@ -1257,6 +1282,22 @@ module Shoulda
           end
         end
 
+        def index_errors_correct?
+          return true unless options.key?(:index_errors)
+
+          if option_verifier.correct_for_boolean?(
+            :index_errors,
+            options[:index_errors]
+          )
+            true
+          else
+            @missing =
+              "#{name} should have index_errors set to " +
+              "#{options[:index_errors]}"
+            false
+          end
+        end
+
         def conditions_correct?
           if options.key?(:conditions)
             if option_verifier.correct_for_relation_clause?(:conditions, options[:conditions])

spec/support/unit/helpers/rails_versions.rb

@@ -34,5 +34,9 @@ module UnitTests
     def rails_lt_5?
       rails_version < 5
     end
+
+    def rails_5_x?
+      rails_version =~ '~> 5.0'
+    end
   end
 end

spec/unit/shoulda/matchers/active_record/association_matcher_spec.rb

@@ -801,6 +801,33 @@ describe Shoulda::Matchers::ActiveRecord::AssociationMatcher, type: :model do
       }.to fail_with_message(message)
     end
 
+    if rails_5_x?
+      context 'index_errors' do
+        it 'accepts an association with a matching :index_errors option' do
+          define_model :child, parent_id: :integer
+          define_model :parent do
+            has_many :children, index_errors: true
+          end
+          expect(Parent.new).to have_many(:children).index_errors(true)
+        end
+
+        it 'rejects an association with a non-matching :index_errors option and returns the correct message' do
+          define_model :child, parent_id: :integer
+          define_model :parent do
+            has_many :children, autosave: false
+          end
+
+          message =
+            'Expected Parent to have a has_many association called children ' +
+            '(children should have index_errors set to true)'
+
+          expect {
+            expect(Parent.new).to have_many(:children).index_errors(true)
+          }.to fail_with_message(message)
+        end
+      end
+    end
+
     context 'validate' do
       it 'accepts when the :validate option matches' do
         expect(having_many_children(validate: false)).to have_many(:children).validate(false)