12 files changed, 82 insertions, 11 deletions
diff --git a/activerecord/test/cases/collection_cache_key_test.rb b/activerecord/test/cases/collection_cache_key_test.rb
index 53058c5a4a..a2874438c1 100644
--- a/activerecord/test/cases/collection_cache_key_test.rb
+++ b/activerecord/test/cases/collection_cache_key_test.rb
@@ -66,5 +66,24 @@ module ActiveRecord
       developers = projects(:active_record).developers
       assert_match(/\Adevelopers\/query-(\h+)-(\d+)-(\d+)\Z/, developers.cache_key)
     end
+
+    test "cache_key for loaded collection with zero size" do
+      Comment.delete_all
+      posts = Post.includes(:comments)
+      empty_loaded_collection = posts.first.comments
+
+      assert_match(/\Acomments\/query-(\h+)-0\Z/, empty_loaded_collection.cache_key)
+    end
+
+    test "cache_key for queries with offset which return 0 rows" do
+      developers = Developer.offset(20)
+      assert_match(/\Adevelopers\/query-(\h+)-0\Z/, developers.cache_key)
+    end
+
+    test "cache_key with a relation having selected columns" do
+      developers = Developer.select(:salary)
+
+      assert_match(/\Adevelopers\/query-(\h+)-(\d+)-(\d+)\Z/, developers.cache_key)
+    end
   end
 end
diff --git a/activerecord/test/cases/enum_test.rb b/activerecord/test/cases/enum_test.rb
index 7c930de97b..babacd1ee9 100644
--- a/activerecord/test/cases/enum_test.rb
+++ b/activerecord/test/cases/enum_test.rb
@@ -411,4 +411,14 @@ class EnumTest < ActiveRecord::TestCase
     assert book.proposed?, "expected fixture to default to proposed status"
     assert book.in_english?, "expected fixture to default to english language"
   end
+
+  test "uses default value from database on initialization" do
+    book = Book.new
+    assert book.proposed?
+  end
+
+  test "uses default value from database on initialization when using custom mapping" do
+    book = Book.new
+    assert book.hard?
+  end
 end
diff --git a/activerecord/test/cases/migration/compatibility_test.rb b/activerecord/test/cases/migration/compatibility_test.rb
index b1e1d72944..6a9cdd9d29 100644
--- a/activerecord/test/cases/migration/compatibility_test.rb
+++ b/activerecord/test/cases/migration/compatibility_test.rb
@@ -53,6 +53,24 @@ module ActiveRecord
         ActiveRecord::Migrator.new(:up, [migration]).migrate
         assert_not connection.index_exists?(:testings, :bar)
       end
+
+      def test_references_does_not_add_index_by_default
+        migration = Class.new(ActiveRecord::Migration) {
+          def migrate(x)
+            create_table :more_testings do |t|
+              t.references :foo
+              t.belongs_to :bar, index: false
+            end
+          end
+        }.new
+
+        ActiveRecord::Migrator.new(:up, [migration]).migrate
+
+        assert_not connection.index_exists?(:more_testings, :foo_id)
+        assert_not connection.index_exists?(:more_testings, :bar_id)
+      ensure
+        connection.drop_table :more_testings rescue nil
+      end
     end
   end
 end
diff --git a/activerecord/test/cases/migration/references_foreign_key_test.rb b/activerecord/test/cases/migration/references_foreign_key_test.rb
index edbc8abe4d..b01415afb2 100644
--- a/activerecord/test/cases/migration/references_foreign_key_test.rb
+++ b/activerecord/test/cases/migration/references_foreign_key_test.rb
@@ -32,10 +32,10 @@ module ActiveRecord
         assert_equal [], @connection.foreign_keys("testings")
       end
 
-      test "foreign keys can be created in one query" do
+      test "foreign keys can be created in one query when index is not added" do
         assert_queries(1) do
           @connection.create_table :testings do |t|
-            t.references :testing_parent, foreign_key: true
+            t.references :testing_parent, foreign_key: true, index: false
           end
         end
       end
diff --git a/activerecord/test/cases/migration/references_index_test.rb b/activerecord/test/cases/migration/references_index_test.rb
index ad6b828d0b..a9a7f0f4c4 100644
--- a/activerecord/test/cases/migration/references_index_test.rb
+++ b/activerecord/test/cases/migration/references_index_test.rb
@@ -23,12 +23,12 @@ module ActiveRecord
         assert connection.index_exists?(table_name, :foo_id, :name => :index_testings_on_foo_id)
       end
 
-      def test_does_not_create_index
+      def test_creates_index_by_default_even_if_index_option_is_not_passed
         connection.create_table table_name do |t|
           t.references :foo
         end
 
-        assert_not connection.index_exists?(table_name, :foo_id, :name => :index_testings_on_foo_id)
+        assert connection.index_exists?(table_name, :foo_id, :name => :index_testings_on_foo_id)
       end
 
       def test_does_not_create_index_explicit
@@ -68,13 +68,13 @@ module ActiveRecord
         assert connection.index_exists?(table_name, :foo_id, :name => :index_testings_on_foo_id)
       end
 
-      def test_does_not_create_index_for_existing_table
+      def test_creates_index_for_existing_table_even_if_index_option_is_not_passed
         connection.create_table table_name
         connection.change_table table_name do |t|
           t.references :foo
         end
 
-        assert_not connection.index_exists?(table_name, :foo_id, :name => :index_testings_on_foo_id)
+        assert connection.index_exists?(table_name, :foo_id, :name => :index_testings_on_foo_id)
       end
 
       def test_does_not_create_index_for_existing_table_explicit
diff --git a/activerecord/test/cases/migration/references_statements_test.rb b/activerecord/test/cases/migration/references_statements_test.rb
index f613fd66c3..b9ce6bbc55 100644
--- a/activerecord/test/cases/migration/references_statements_test.rb
+++ b/activerecord/test/cases/migration/references_statements_test.rb
@@ -30,14 +30,14 @@ module ActiveRecord
         assert column_exists?(table_name, :taggable_type, :string)
       end
 
-      def test_creates_reference_id_index
-        add_reference table_name, :user, index: true
-        assert index_exists?(table_name, :user_id)
+      def test_does_not_create_reference_id_index_if_index_is_false
+        add_reference table_name, :user, index: false
+        assert_not index_exists?(table_name, :user_id)
       end
 
-      def test_does_not_create_reference_id_index
+      def test_create_reference_id_index_even_if_index_option_is_passed
         add_reference table_name, :user
-        assert_not index_exists?(table_name, :user_id)
+        assert index_exists?(table_name, :user_id)
       end
 
       def test_creates_polymorphic_index
diff --git a/activerecord/test/cases/reflection_test.rb b/activerecord/test/cases/reflection_test.rb
index 9c04a41e69..710c86b151 100644
--- a/activerecord/test/cases/reflection_test.rb
+++ b/activerecord/test/cases/reflection_test.rb
@@ -23,6 +23,7 @@ require 'models/chef'
 require 'models/department'
 require 'models/cake_designer'
 require 'models/drink_designer'
+require 'models/mocktail_designer'
 require 'models/recipe'
 
 class ReflectionTest < ActiveRecord::TestCase
@@ -278,6 +279,15 @@ class ReflectionTest < ActiveRecord::TestCase
     assert_equal 2, @hotel.chefs.size
   end
 
+  def test_scope_chain_does_not_interfere_with_hmt_with_polymorphic_case_and_sti
+    @hotel = Hotel.create!
+    @hotel.mocktail_designers << MocktailDesigner.create!
+
+    assert_equal 1, @hotel.mocktail_designers.size
+    assert_equal 1, @hotel.mocktail_designers.count
+    assert_equal 1, @hotel.chef_lists.size
+  end
+
   def test_scope_chain_of_polymorphic_association_does_not_leak_into_other_hmt_associations
     hotel = Hotel.create!
     department = hotel.departments.create!
diff --git a/activerecord/test/models/book.rb b/activerecord/test/models/book.rb
index 1927191393..e43e5c3901 100644
--- a/activerecord/test/models/book.rb
+++ b/activerecord/test/models/book.rb
@@ -14,6 +14,7 @@ class Book < ActiveRecord::Base
   enum author_visibility: [:visible, :invisible], _prefix: true
   enum illustrator_visibility: [:visible, :invisible], _prefix: true
   enum font_size: [:small, :medium, :large], _prefix: :with, _suffix: true
+  enum cover: { hard: 'hard', soft: 'soft' }
 
   def published!
     super
diff --git a/activerecord/test/models/chef.rb b/activerecord/test/models/chef.rb
index 698a52e045..9d3dd01016 100644
--- a/activerecord/test/models/chef.rb
+++ b/activerecord/test/models/chef.rb
@@ -2,3 +2,7 @@ class Chef < ActiveRecord::Base
   belongs_to :employable, polymorphic: true
   has_many :recipes
 end
+
+class ChefList < Chef
+  belongs_to :employable_list, polymorphic: true
+end
diff --git a/activerecord/test/models/hotel.rb b/activerecord/test/models/hotel.rb
index 491f8dfde3..9c90ffcff4 100644
--- a/activerecord/test/models/hotel.rb
+++ b/activerecord/test/models/hotel.rb
@@ -3,5 +3,9 @@ class Hotel < ActiveRecord::Base
   has_many :chefs, through: :departments
   has_many :cake_designers, source_type: 'CakeDesigner', source: :employable, through: :chefs
   has_many :drink_designers, source_type: 'DrinkDesigner', source: :employable, through: :chefs
+
+  has_many :chef_lists, as: :employable_list
+  has_many :mocktail_designers, through: :chef_lists, source: :employable, :source_type => "MocktailDesigner"
+
   has_many :recipes, through: :chefs
 end
diff --git a/activerecord/test/models/mocktail_designer.rb b/activerecord/test/models/mocktail_designer.rb
new file mode 100644
index 0000000000..77b44651a3
--- /dev/null
+++ b/activerecord/test/models/mocktail_designer.rb
@@ -0,0 +1,2 @@
+class MocktailDesigner < DrinkDesigner
+end
diff --git a/activerecord/test/schema/schema.rb b/activerecord/test/schema/schema.rb
index 025184f63a..fcc4eee79c 100644
--- a/activerecord/test/schema/schema.rb
+++ b/activerecord/test/schema/schema.rb
@@ -104,6 +104,7 @@ ActiveRecord::Schema.define do
     t.column :author_visibility, :integer, default: 0
     t.column :illustrator_visibility, :integer, default: 0
     t.column :font_size, :integer, default: 0
+    t.column :cover, :string, default: 'hard'
   end
 
   create_table :booleans, force: true do |t|
@@ -975,6 +976,8 @@ ActiveRecord::Schema.define do
     t.integer :employable_id
     t.string :employable_type
     t.integer :department_id
+    t.string :employable_list_type
+    t.integer :employable_list_id
   end
   create_table :recipes, force: true do |t|
     t.integer :chef_id