Merge branch 'master' into laurocaetano-fix_send_file

* master: (536 commits)
  doc, API example on how to use `Model#exists?` with multiple IDs. [ci skip]
  Restore DATABASE_URL even if it's nil in connection_handler test
  [ci skip] - error_messages_for has been deprecated since 2.3.8 - lets reduce any confusion for users
  Ensure Active Record connection consistency
  Revert "ask the fixture set for the sql statements"
  Check `respond_to` before delegation due to: https://github.com/ruby/ruby/commit/d781caaf313b8649948c107bba277e5ad7307314
  Adding Hash#compact and Hash#compact! methods
  MySQL version 4.1 was EOL on December 31, 2009 We should at least recommend modern versions of MySQL to users.
  clear cache on body close so that cache remains during rendering
  add a more restricted codepath for templates fixes #13390
  refactor generator tests to use block form of Tempfile
  Fix typo [ci skip]
  Move finish_template as the last public method in the generator
  Minor typos fix [ci skip]
  make `change_column_null` reversible. Closes #13576.
  create/drop test and development databases only if RAILS_ENV is nil
  Revert "Speedup String#to"
  typo fix in test name. [ci skip].
  `core_ext/string/access.rb` test what we are documenting.
  Fix typo in image_tag documentation
  ...

Conflicts:
	actionpack/CHANGELOG.md

1 files changed, 21 insertions, 0 deletions

diff --git a/activerecord/test/cases/associations/belongs_to_associations_test.rb b/activerecord/test/cases/associations/belongs_to_associations_test.rb
index 7c913bc78b..3205d0c28b 100644
--- a/activerecord/test/cases/associations/belongs_to_associations_test.rb
+++ b/activerecord/test/cases/associations/belongs_to_associations_test.rb
@@ -356,6 +356,14 @@ class BelongsToAssociationsTest < ActiveRecord::TestCase
     assert_queries(2) { line_item.destroy }
   end
 
+  def test_belongs_to_with_touch_option_on_destroy_with_destroyed_parent
+    line_item = LineItem.create!
+    invoice   = Invoice.create!(line_items: [line_item])
+    invoice.destroy
+
+    assert_queries(1) { line_item.destroy }
+  end
+
   def test_belongs_to_with_touch_option_on_touch_and_reassigned_parent
     line_item = LineItem.create!
     Invoice.create!(line_items: [line_item])
@@ -578,6 +586,19 @@ class BelongsToAssociationsTest < ActiveRecord::TestCase
     assert_nil essay.writer_id
   end
 
+  def test_polymorphic_assignment_with_nil
+    essay = Essay.new
+    assert_nil essay.writer_id
+    assert_nil essay.writer_type
+
+    essay.writer_id = 1
+    essay.writer_type = 'Author'
+
+    essay.writer = nil
+    assert_nil essay.writer_id
+    assert_nil essay.writer_type
+  end
+
   def test_belongs_to_proxy_should_not_respond_to_private_methods
     assert_raise(NoMethodError) { companies(:first_firm).private_method }
     assert_raise(NoMethodError) { companies(:second_client).firm.private_method }