Move the `ActiveModel:Errors#full_message` method to the `Error` class:

- One regression introduced by the "AM errors as object" features is
  about the `full_messages` method.

  It's currently impossible to call that method if the `base` object
  passed in the constructor of `AM::Errors` doesn't respond to the
  `errors` method.
  That's because `full_messages` now makes a weird back and forth trip

  `AM::Errors#full_messages` -> `AM::Error#full_message` -> `AM::Errors#full_message`

  Since `full_message` (singular) isn't needed by AM::Errors, I moved
  it to the `AM::Error` (singular) class. This way we don't need to
  grab the `AM::Errors` object from the base.

1 files changed, 2 insertions, 2 deletions

diff --git a/activerecord/test/cases/validations/i18n_validation_test.rb b/activerecord/test/cases/validations/i18n_validation_test.rb
index 2645776ab7..4dd8a4a82b 100644
--- a/activerecord/test/cases/validations/i18n_validation_test.rb
+++ b/activerecord/test/cases/validations/i18n_validation_test.rb
@@ -51,7 +51,7 @@ class I18nValidationTest < ActiveRecord::TestCase
     test "validates_uniqueness_of on generated message #{name}" do
       Topic.validates_uniqueness_of :title, validation_options
       @topic.title = unique_topic.title
-      assert_called_with(@topic.errors, :generate_message, [:title, :taken, generate_message_options.merge(value: "unique!")]) do
+      assert_called_with(ActiveModel::Error, :generate_message, [:title, :taken, @topic, generate_message_options.merge(value: "unique!")]) do
         @topic.valid?
         @topic.errors.messages
       end
@@ -61,7 +61,7 @@ class I18nValidationTest < ActiveRecord::TestCase
   COMMON_CASES.each do |name, validation_options, generate_message_options|
     test "validates_associated on generated message #{name}" do
       Topic.validates_associated :replies, validation_options
-      assert_called_with(replied_topic.errors, :generate_message, [:replies, :invalid, generate_message_options.merge(value: replied_topic.replies)]) do
+      assert_called_with(ActiveModel::Error, :generate_message, [:replies, :invalid, replied_topic, generate_message_options.merge(value: replied_topic.replies)]) do
         replied_topic.save
         replied_topic.errors.messages
       end