Add test case for autosave association with nested attributes.

activerecord/test/cases/autosave_association_test.rb

@@ -17,6 +17,8 @@
 require 'models/tagging'
 require 'models/treasure'
 require 'models/eye'
+require 'models/electron'
+require 'models/molecule'
 
 class TestAutosaveAssociationsInGeneral < ActiveRecord::TestCase
   def test_should_not_add_the_same_callbacks_multiple_times_for_has_one
@@ -343,6 +345,33 @@ def test_validation_does_not_validate_stale_association_target
   end
 end
 
+class TestDefaultAutosaveAssociationOnAHasManyAssociationWithAcceptsNestedAttributes < ActiveRecord::TestCase
+  def test_invalid_adding_with_nested_attributes
+    molecule = Molecule.new
+    valid_electron = Electron.new(name: 'electron')
+    invalid_electron = Electron.new
+
+    molecule.electrons = [valid_electron, invalid_electron]
+    molecule.save
+
+    assert_not invalid_electron.valid?
+    assert valid_electron.valid?
+    assert_not molecule.persisted?, 'Molecule should not be persisted when its electrons are invalid'
+  end
+
+  def test_valid_adding_with_nested_attributes
+    molecule = Molecule.new
+    valid_electron = Electron.new(name: 'electron')
+
+    molecule.electrons = [valid_electron]
+    molecule.save
+
+    assert valid_electron.valid?
+    assert molecule.persisted?
+    assert_equal 1, molecule.electrons.count
+  end
+end
+
 class TestDefaultAutosaveAssociationOnAHasManyAssociation < ActiveRecord::TestCase
   fixtures :companies, :people
 

activerecord/test/models/electron.rb

@@ -1,3 +1,5 @@
 class Electron < ActiveRecord::Base
   belongs_to :molecule
+
+  validates_presence_of :name
 end

activerecord/test/models/molecule.rb

@@ -1,4 +1,6 @@
 class Molecule < ActiveRecord::Base
   belongs_to :liquid
   has_many :electrons
+
+  accepts_nested_attributes_for :electrons
 end