2 files changed, 14 insertions, 28 deletions
diff --git a/activerecord/test/cases/associations/eager_test.rb b/activerecord/test/cases/associations/eager_test.rb
index 39034746c9..b37e59038e 100644
--- a/activerecord/test/cases/associations/eager_test.rb
+++ b/activerecord/test/cases/associations/eager_test.rb
@@ -34,7 +34,7 @@ class EagerLoadingTooManyIdsTest < ActiveRecord::TestCase
   fixtures :citations
 
   def test_preloading_too_many_ids
-    assert_equal Citation.count, Citation.preload(:citations).to_a.size
+    assert_equal Citation.count, Citation.preload(:reference_of).to_a.size
   end
 
   def test_eager_loading_too_may_ids
@@ -1618,32 +1618,6 @@ class EagerAssociationTest < ActiveRecord::TestCase
     end
   end
 
-  # Associations::Preloader#preloaders_on works with hash-like objects
-  test "preloading works with an object that responds to :to_hash" do
-    CustomHash = Class.new(Hash)
-
-    assert_nothing_raised do
-      Post.preload(CustomHash.new(comments: [{ author: :essays }])).first
-    end
-  end
-
-  # Associations::Preloader#preloaders_on works with string-like objects
-  test "preloading works with an object that responds to :to_str" do
-    CustomString = Class.new(String)
-
-    assert_nothing_raised do
-      Post.preload(CustomString.new("comments")).first
-    end
-  end
-
-  # Associations::Preloader#preloaders_on does not work with ranges
-  test "preloading fails when Range is passed" do
-    exception = assert_raises(ArgumentError) do
-      Post.preload(1..10).first
-    end
-    assert_equal("1..10 was not recognized for preload", exception.message)
-  end
-
   private
     def find_all_ordered(klass, include = nil)
       klass.order("#{klass.table_name}.#{klass.primary_key}").includes(include).to_a
diff --git a/activerecord/test/cases/associations/has_and_belongs_to_many_associations_test.rb b/activerecord/test/cases/associations/has_and_belongs_to_many_associations_test.rb
index 38b121d37b..515eb65d37 100644
--- a/activerecord/test/cases/associations/has_and_belongs_to_many_associations_test.rb
+++ b/activerecord/test/cases/associations/has_and_belongs_to_many_associations_test.rb
@@ -25,6 +25,8 @@ require "models/user"
 require "models/member"
 require "models/membership"
 require "models/sponsor"
+require "models/lesson"
+require "models/student"
 require "models/country"
 require "models/treaty"
 require "models/vertex"
@@ -275,7 +277,7 @@ class HasAndBelongsToManyAssociationsTest < ActiveRecord::TestCase
   def test_habtm_saving_multiple_relationships
     new_project = Project.new("name" => "Grimetime")
     amount_of_developers = 4
-    developers = (0...amount_of_developers).collect { |i| Developer.create(name: "JME #{i}") }.reverse
+    developers = (0...amount_of_developers).reverse_each.map { |i| Developer.create(name: "JME #{i}") }
 
     new_project.developer_ids = [developers[0].id, developers[1].id]
     new_project.developers_with_callback_ids = [developers[2].id, developers[3].id]
@@ -780,6 +782,16 @@ class HasAndBelongsToManyAssociationsTest < ActiveRecord::TestCase
     assert_equal [projects(:active_record), projects(:action_controller)].map(&:id).sort, developer.project_ids.sort
   end
 
+  def test_singular_ids_are_reloaded_after_collection_concat
+    student = Student.create(name: "Alberto Almagro")
+    student.lesson_ids
+
+    lesson = Lesson.create(name: "DSI")
+    student.lessons << lesson
+
+    assert_includes student.lesson_ids, lesson.id
+  end
+
   def test_scoped_find_on_through_association_doesnt_return_read_only_records
     tag = Post.find(1).tags.find_by_name("General")