Rase when calling `lock!` in a dirty record

activerecord/CHANGELOG.md

@@ -1,3 +1,7 @@
*   Raises when calling `lock!` in a dirty record.

    *Rafael Mendonça França*

*   Remove deprecated support to passing a class to `:class_name` on associations.

    *Rafael Mendonça França*

activerecord/lib/active_record/locking/pessimistic.rb

@@ -63,12 +63,13 @@ module Pessimistic
      def lock!(lock = true)
        if persisted?
          if changed?
            ActiveSupport::Deprecation.warn(<<-MSG.squish)
              Locking a record with unpersisted changes is deprecated and will raise an
              exception in Rails 5.2. Use `save` to persist the changes, or `reload` to
              discard them explicitly.
            raise(<<-MSG.squish)
              Locking a record with unpersisted changes is not supported. Use
              `save` to persist the changes, or `reload` to discard them
              explicitly.
            MSG
          end

          reload(lock: lock)
        end
        self

activerecord/test/cases/locking_test.rb

@@ -565,18 +565,18 @@ def test_eager_find_with_lock
      end
    end

    # Locking a record reloads it.
    def test_sane_lock_method
    def test_lock_does_not_raise_when_the_object_is_not_dirty
      person = Person.find 1
      assert_nothing_raised do
        Person.transaction do
          person = Person.find 1
          old, person.first_name = person.first_name, "fooman"
          # Locking a dirty record is deprecated
          assert_deprecated do
            person.lock!
          end
          assert_equal old, person.first_name
        end
        person.lock!
      end
    end

    def test_lock_raises_when_the_record_is_dirty
      person = Person.find 1
      person.first_name = "fooman"
      assert_raises(RuntimeError) do
        person.lock!
      end
    end