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.

7 files changed, 159 insertions, 129 deletions

diff --git a/activemodel/lib/active_model.rb b/activemodel/lib/active_model.rb
index c9140dc582..756473e38d 100644
--- a/activemodel/lib/active_model.rb
+++ b/activemodel/lib/active_model.rb
@@ -53,6 +53,7 @@ module ActiveModel
 
   eager_autoload do
     autoload :Errors
+    autoload :Error
     autoload :RangeError, "active_model/errors"
     autoload :StrictValidationFailed, "active_model/errors"
     autoload :UnknownAttributeError, "active_model/errors"
diff --git a/activemodel/lib/active_model/error.rb b/activemodel/lib/active_model/error.rb
index ea141fe107..aef28b5af0 100644
--- a/activemodel/lib/active_model/error.rb
+++ b/activemodel/lib/active_model/error.rb
@@ -8,6 +8,92 @@ module ActiveModel
     CALLBACKS_OPTIONS = [:if, :unless, :on, :allow_nil, :allow_blank, :strict]
     MESSAGE_OPTIONS = [:message]
 
+    class << self
+      attr_accessor :i18n_customize_full_message # :nodoc:
+    end
+    self.i18n_customize_full_message = false
+
+    def self.full_message(attribute, message, base_class) # :nodoc:
+      return message if attribute == :base
+      attribute = attribute.to_s
+
+      if i18n_customize_full_message && base_class.respond_to?(:i18n_scope)
+        attribute = attribute.remove(/\[\d\]/)
+        parts = attribute.split(".")
+        attribute_name = parts.pop
+        namespace = parts.join("/") unless parts.empty?
+        attributes_scope = "#{base_class.i18n_scope}.errors.models"
+
+        if namespace
+          defaults = base_class.lookup_ancestors.map do |klass|
+            [
+              :"#{attributes_scope}.#{klass.model_name.i18n_key}/#{namespace}.attributes.#{attribute_name}.format",
+              :"#{attributes_scope}.#{klass.model_name.i18n_key}/#{namespace}.format",
+            ]
+          end
+        else
+          defaults = base_class.lookup_ancestors.map do |klass|
+            [
+              :"#{attributes_scope}.#{klass.model_name.i18n_key}.attributes.#{attribute_name}.format",
+              :"#{attributes_scope}.#{klass.model_name.i18n_key}.format",
+            ]
+          end
+        end
+
+        defaults.flatten!
+      else
+        defaults = []
+      end
+
+      defaults << :"errors.format"
+      defaults << "%{attribute} %{message}"
+
+      attr_name = attribute.tr(".", "_").humanize
+      attr_name = base_class.human_attribute_name(attribute, default: attr_name)
+
+      I18n.t(defaults.shift,
+        default:  defaults,
+        attribute: attr_name,
+        message:   message)
+    end
+
+    def self.generate_message(attribute, type, base, options) # :nodoc:
+      type = options.delete(:message) if options[:message].is_a?(Symbol)
+      value = (attribute != :base ? base.send(:read_attribute_for_validation, attribute) : nil)
+
+      options = {
+        model: base.model_name.human,
+        attribute: base.class.human_attribute_name(attribute),
+        value: value,
+        object: base
+      }.merge!(options)
+
+      if base.class.respond_to?(:i18n_scope)
+        i18n_scope = base.class.i18n_scope.to_s
+        defaults = base.class.lookup_ancestors.flat_map do |klass|
+          [ :"#{i18n_scope}.errors.models.#{klass.model_name.i18n_key}.attributes.#{attribute}.#{type}",
+            :"#{i18n_scope}.errors.models.#{klass.model_name.i18n_key}.#{type}" ]
+        end
+        defaults << :"#{i18n_scope}.errors.messages.#{type}"
+
+        catch(:exception) do
+          translation = I18n.translate(defaults.first, options.merge(default: defaults.drop(1), throw: true))
+          return translation unless translation.nil?
+        end unless options[:message]
+      else
+        defaults = []
+      end
+
+      defaults << :"errors.attributes.#{attribute}.#{type}"
+      defaults << :"errors.messages.#{type}"
+
+      key = defaults.shift
+      defaults = options.delete(:message) if options[:message]
+      options[:default] = defaults
+
+      I18n.translate(key, options)
+    end
+
     def initialize(base, attribute, type = :invalid, **options)
       @base = base
       @attribute = attribute
@@ -28,7 +114,7 @@ module ActiveModel
     def message
       case raw_type
       when Symbol
-        base.errors.generate_message(attribute, raw_type, options.except(*CALLBACKS_OPTIONS))
+        self.class.generate_message(attribute, raw_type, @base, options.except(*CALLBACKS_OPTIONS))
       else
         raw_type
       end
@@ -39,7 +125,7 @@ module ActiveModel
     end
 
     def full_message
-      base.errors.full_message(attribute, message)
+      self.class.full_message(attribute, message, @base.class)
     end
 
     # See if error matches provided +attribute+, +type+ and +options+.
diff --git a/activemodel/lib/active_model/errors.rb b/activemodel/lib/active_model/errors.rb
index e9f92dba82..22839bd9fb 100644
--- a/activemodel/lib/active_model/errors.rb
+++ b/activemodel/lib/active_model/errors.rb
@@ -69,11 +69,6 @@ module ActiveModel
 
     LEGACY_ATTRIBUTES = [:messages, :details].freeze
 
-    class << self
-      attr_accessor :i18n_customize_full_message # :nodoc:
-    end
-    self.i18n_customize_full_message = false
-
     attr_reader :errors
     alias :objects :errors
 
@@ -467,47 +462,7 @@ module ActiveModel
     #
     #   person.errors.full_message(:name, 'is invalid') # => "Name is invalid"
     def full_message(attribute, message)
-      return message if attribute == :base
-      attribute = attribute.to_s
-
-      if self.class.i18n_customize_full_message && @base.class.respond_to?(:i18n_scope)
-        attribute = attribute.remove(/\[\d\]/)
-        parts = attribute.split(".")
-        attribute_name = parts.pop
-        namespace = parts.join("/") unless parts.empty?
-        attributes_scope = "#{@base.class.i18n_scope}.errors.models"
-
-        if namespace
-          defaults = @base.class.lookup_ancestors.map do |klass|
-            [
-              :"#{attributes_scope}.#{klass.model_name.i18n_key}/#{namespace}.attributes.#{attribute_name}.format",
-              :"#{attributes_scope}.#{klass.model_name.i18n_key}/#{namespace}.format",
-            ]
-          end
-        else
-          defaults = @base.class.lookup_ancestors.map do |klass|
-            [
-              :"#{attributes_scope}.#{klass.model_name.i18n_key}.attributes.#{attribute_name}.format",
-              :"#{attributes_scope}.#{klass.model_name.i18n_key}.format",
-            ]
-          end
-        end
-
-        defaults.flatten!
-      else
-        defaults = []
-      end
-
-      defaults << :"errors.format"
-      defaults << "%{attribute} %{message}"
-
-      attr_name = attribute.tr(".", "_").humanize
-      attr_name = @base.class.human_attribute_name(attribute, default: attr_name)
-
-      I18n.t(defaults.shift,
-        default:  defaults,
-        attribute: attr_name,
-        message:   message)
+      Error.full_message(attribute, message, @base.class)
     end
 
     # Translates an error message in its default scope
@@ -535,40 +490,7 @@ module ActiveModel
     # * <tt>errors.attributes.title.blank</tt>
     # * <tt>errors.messages.blank</tt>
     def generate_message(attribute, type = :invalid, options = {})
-      type = options.delete(:message) if options[:message].is_a?(Symbol)
-      value = (attribute != :base ? @base.send(:read_attribute_for_validation, attribute) : nil)
-
-      options = {
-        model: @base.model_name.human,
-        attribute: @base.class.human_attribute_name(attribute),
-        value: value,
-        object: @base
-      }.merge!(options)
-
-      if @base.class.respond_to?(:i18n_scope)
-        i18n_scope = @base.class.i18n_scope.to_s
-        defaults = @base.class.lookup_ancestors.flat_map do |klass|
-          [ :"#{i18n_scope}.errors.models.#{klass.model_name.i18n_key}.attributes.#{attribute}.#{type}",
-            :"#{i18n_scope}.errors.models.#{klass.model_name.i18n_key}.#{type}" ]
-        end
-        defaults << :"#{i18n_scope}.errors.messages.#{type}"
-
-        catch(:exception) do
-          translation = I18n.translate(defaults.first, options.merge(default: defaults.drop(1), throw: true))
-          return translation unless translation.nil?
-        end unless options[:message]
-      else
-        defaults = []
-      end
-
-      defaults << :"errors.attributes.#{attribute}.#{type}"
-      defaults << :"errors.messages.#{type}"
-
-      key = defaults.shift
-      defaults = options.delete(:message) if options[:message]
-      options[:default] = defaults
-
-      I18n.translate(key, options)
+      Error.generate_message(attribute, type, @base, options)
     end
 
     def marshal_load(array) # :nodoc:
diff --git a/activemodel/lib/active_model/railtie.rb b/activemodel/lib/active_model/railtie.rb
index eb7901c7e9..65e20b9791 100644
--- a/activemodel/lib/active_model/railtie.rb
+++ b/activemodel/lib/active_model/railtie.rb
@@ -14,7 +14,7 @@ module ActiveModel
     end
 
     initializer "active_model.i18n_customize_full_message" do
-      ActiveModel::Errors.i18n_customize_full_message = config.active_model.delete(:i18n_customize_full_message) || false
+      ActiveModel::Error.i18n_customize_full_message = config.active_model.delete(:i18n_customize_full_message) || false
     end
   end
 end
diff --git a/activemodel/test/cases/errors_test.rb b/activemodel/test/cases/errors_test.rb
index 9d31ed0a99..d66d6ceff0 100644
--- a/activemodel/test/cases/errors_test.rb
+++ b/activemodel/test/cases/errors_test.rb
@@ -482,6 +482,27 @@ class ErrorsTest < ActiveModel::TestCase
     assert_nil person.errors.as_json.default_proc
   end
 
+  test "full_messages doesn't require the base object to respond to `:errors" do
+    model = Class.new do
+      def initialize
+        @errors = ActiveModel::Errors.new(self)
+        @errors.add(:name, "bar")
+      end
+
+      def self.human_attribute_name(attr, options = {})
+        "foo"
+      end
+
+      def call
+        error_wrapper = Struct.new(:model_errors)
+
+        error_wrapper.new(@errors)
+      end
+    end
+
+    assert_equal(["foo bar"], model.new.call.model_errors.full_messages)
+  end
+
   test "full_messages creates a list of error messages with the attribute name included" do
     person = Person.new
     person.errors.add(:name, "cannot be blank")
diff --git a/activemodel/test/cases/railtie_test.rb b/activemodel/test/cases/railtie_test.rb
index 95ee7cace3..f5ff1a3fd7 100644
--- a/activemodel/test/cases/railtie_test.rb
+++ b/activemodel/test/cases/railtie_test.rb
@@ -35,20 +35,20 @@ class RailtieTest < ActiveModel::TestCase
   test "i18n customize full message defaults to false" do
     @app.initialize!
 
-    assert_equal false, ActiveModel::Errors.i18n_customize_full_message
+    assert_equal false, ActiveModel::Error.i18n_customize_full_message
   end
 
   test "i18n customize full message can be disabled" do
     @app.config.active_model.i18n_customize_full_message = false
     @app.initialize!
 
-    assert_equal false, ActiveModel::Errors.i18n_customize_full_message
+    assert_equal false, ActiveModel::Error.i18n_customize_full_message
   end
 
   test "i18n customize full message can be enabled" do
     @app.config.active_model.i18n_customize_full_message = true
     @app.initialize!
 
-    assert_equal true, ActiveModel::Errors.i18n_customize_full_message
+    assert_equal true, ActiveModel::Error.i18n_customize_full_message
   end
 end
diff --git a/activemodel/test/cases/validations/i18n_validation_test.rb b/activemodel/test/cases/validations/i18n_validation_test.rb
index b7ee50832c..ea5b335f44 100644
--- a/activemodel/test/cases/validations/i18n_validation_test.rb
+++ b/activemodel/test/cases/validations/i18n_validation_test.rb
@@ -13,8 +13,8 @@ class I18nValidationTest < ActiveModel::TestCase
     I18n.backend = I18n::Backend::Simple.new
     I18n.backend.store_translations("en", errors: { messages: { custom: nil } })
 
-    @original_i18n_customize_full_message = ActiveModel::Errors.i18n_customize_full_message
-    ActiveModel::Errors.i18n_customize_full_message = true
+    @original_i18n_customize_full_message = ActiveModel::Error.i18n_customize_full_message
+    ActiveModel::Error.i18n_customize_full_message = true
   end
 
   def teardown
@@ -24,7 +24,7 @@ class I18nValidationTest < ActiveModel::TestCase
     I18n.load_path.replace @old_load_path
     I18n.backend = @old_backend
     I18n.backend.reload!
-    ActiveModel::Errors.i18n_customize_full_message = @original_i18n_customize_full_message
+    ActiveModel::Error.i18n_customize_full_message = @original_i18n_customize_full_message
   end
 
   def test_full_message_encoding
@@ -49,7 +49,7 @@ class I18nValidationTest < ActiveModel::TestCase
   end
 
   def test_errors_full_messages_doesnt_use_attribute_format_without_config
-    ActiveModel::Errors.i18n_customize_full_message = false
+    ActiveModel::Error.i18n_customize_full_message = false
 
     I18n.backend.store_translations("en", activemodel: {
       errors: { models: { person: { attributes: { name: { format: "%{message}" } } } } } })
@@ -60,7 +60,7 @@ class I18nValidationTest < ActiveModel::TestCase
   end
 
   def test_errors_full_messages_uses_attribute_format
-    ActiveModel::Errors.i18n_customize_full_message = true
+    ActiveModel::Error.i18n_customize_full_message = true
 
     I18n.backend.store_translations("en", activemodel: {
       errors: { models: { person: { attributes: { name: { format: "%{message}" } } } } } })
@@ -71,7 +71,7 @@ class I18nValidationTest < ActiveModel::TestCase
   end
 
   def test_errors_full_messages_uses_model_format
-    ActiveModel::Errors.i18n_customize_full_message = true
+    ActiveModel::Error.i18n_customize_full_message = true
 
     I18n.backend.store_translations("en", activemodel: {
       errors: { models: { person: { format: "%{message}" } } } })
@@ -82,7 +82,7 @@ class I18nValidationTest < ActiveModel::TestCase
   end
 
   def test_errors_full_messages_uses_deeply_nested_model_attributes_format
-    ActiveModel::Errors.i18n_customize_full_message = true
+    ActiveModel::Error.i18n_customize_full_message = true
 
     I18n.backend.store_translations("en", activemodel: {
       errors: { models: { 'person/contacts/addresses': { attributes: { street: { format: "%{message}" } } } } } })
@@ -93,7 +93,7 @@ class I18nValidationTest < ActiveModel::TestCase
   end
 
   def test_errors_full_messages_uses_deeply_nested_model_model_format
-    ActiveModel::Errors.i18n_customize_full_message = true
+    ActiveModel::Error.i18n_customize_full_message = true
 
     I18n.backend.store_translations("en", activemodel: {
       errors: { models: { 'person/contacts/addresses': { format: "%{message}" } } } })
@@ -104,7 +104,7 @@ class I18nValidationTest < ActiveModel::TestCase
   end
 
   def test_errors_full_messages_with_indexed_deeply_nested_attributes_and_attributes_format
-    ActiveModel::Errors.i18n_customize_full_message = true
+    ActiveModel::Error.i18n_customize_full_message = true
 
     I18n.backend.store_translations("en", activemodel: {
       errors: { models: { 'person/contacts/addresses': { attributes: { street: { format: "%{message}" } } } } } })
@@ -115,7 +115,7 @@ class I18nValidationTest < ActiveModel::TestCase
   end
 
   def test_errors_full_messages_with_indexed_deeply_nested_attributes_and_model_format
-    ActiveModel::Errors.i18n_customize_full_message = true
+    ActiveModel::Error.i18n_customize_full_message = true
 
     I18n.backend.store_translations("en", activemodel: {
       errors: { models: { 'person/contacts/addresses': { format: "%{message}" } } } })
@@ -126,7 +126,7 @@ class I18nValidationTest < ActiveModel::TestCase
   end
 
   def test_errors_full_messages_with_indexed_deeply_nested_attributes_and_i18n_attribute_name
-    ActiveModel::Errors.i18n_customize_full_message = true
+    ActiveModel::Error.i18n_customize_full_message = true
 
     I18n.backend.store_translations("en", activemodel: {
       attributes: { 'person/contacts/addresses': { country: "Country" } }
@@ -138,7 +138,7 @@ class I18nValidationTest < ActiveModel::TestCase
   end
 
   def test_errors_full_messages_with_indexed_deeply_nested_attributes_without_i18n_config
-    ActiveModel::Errors.i18n_customize_full_message = false
+    ActiveModel::Error.i18n_customize_full_message = false
 
     I18n.backend.store_translations("en", activemodel: {
       errors: { models: { 'person/contacts/addresses': { attributes: { street: { format: "%{message}" } } } } } })
@@ -149,7 +149,7 @@ class I18nValidationTest < ActiveModel::TestCase
   end
 
   def test_errors_full_messages_with_i18n_attribute_name_without_i18n_config
-    ActiveModel::Errors.i18n_customize_full_message = false
+    ActiveModel::Error.i18n_customize_full_message = false
 
     I18n.backend.store_translations("en", activemodel: {
       attributes: { 'person/contacts[0]/addresses[0]': { country: "Country" } }
@@ -178,8 +178,8 @@ class I18nValidationTest < ActiveModel::TestCase
     test "validates_confirmation_of on generated message #{name}" do
       person_class.validates_confirmation_of :title, validation_options
       @person.title_confirmation = "foo"
-      call = [:title_confirmation, :confirmation, generate_message_options.merge(attribute: "Title")]
-      assert_called_with(@person.errors, :generate_message, call) do
+      call = [:title_confirmation, :confirmation, @person, generate_message_options.merge(attribute: "Title")]
+      assert_called_with(ActiveModel::Error, :generate_message, call) do
         @person.valid?
         @person.errors.messages
       end
@@ -189,8 +189,8 @@ class I18nValidationTest < ActiveModel::TestCase
   COMMON_CASES.each do |name, validation_options, generate_message_options|
     test "validates_acceptance_of on generated message #{name}" do
       person_class.validates_acceptance_of :title, validation_options.merge(allow_nil: false)
-      call = [:title, :accepted, generate_message_options]
-      assert_called_with(@person.errors, :generate_message, call) do
+      call = [:title, :accepted, @person, generate_message_options]
+      assert_called_with(ActiveModel::Error, :generate_message, call) do
         @person.valid?
         @person.errors.messages
       end
@@ -200,8 +200,8 @@ class I18nValidationTest < ActiveModel::TestCase
   COMMON_CASES.each do |name, validation_options, generate_message_options|
     test "validates_presence_of on generated message #{name}" do
       person_class.validates_presence_of :title, validation_options
-      call = [:title, :blank, generate_message_options]
-      assert_called_with(@person.errors, :generate_message, call) do
+      call = [:title, :blank, @person, generate_message_options]
+      assert_called_with(ActiveModel::Error, :generate_message, call) do
         @person.valid?
         @person.errors.messages
       end
@@ -211,8 +211,8 @@ class I18nValidationTest < ActiveModel::TestCase
   COMMON_CASES.each do |name, validation_options, generate_message_options|
     test "validates_length_of for :within on generated message when too short #{name}" do
       person_class.validates_length_of :title, validation_options.merge(within: 3..5)
-      call = [:title, :too_short, generate_message_options.merge(count: 3)]
-      assert_called_with(@person.errors, :generate_message, call) do
+      call = [:title, :too_short, @person, generate_message_options.merge(count: 3)]
+      assert_called_with(ActiveModel::Error, :generate_message, call) do
         @person.valid?
         @person.errors.messages
       end
@@ -223,8 +223,8 @@ class I18nValidationTest < ActiveModel::TestCase
     test "validates_length_of for :too_long generated message #{name}" do
       person_class.validates_length_of :title, validation_options.merge(within: 3..5)
       @person.title = "this title is too long"
-      call = [:title, :too_long, generate_message_options.merge(count: 5)]
-      assert_called_with(@person.errors, :generate_message, call) do
+      call = [:title, :too_long, @person, generate_message_options.merge(count: 5)]
+      assert_called_with(ActiveModel::Error, :generate_message, call) do
         @person.valid?
         @person.errors.messages
       end
@@ -234,8 +234,8 @@ class I18nValidationTest < ActiveModel::TestCase
   COMMON_CASES.each do |name, validation_options, generate_message_options|
     test "validates_length_of for :is on generated message #{name}" do
       person_class.validates_length_of :title, validation_options.merge(is: 5)
-      call = [:title, :wrong_length, generate_message_options.merge(count: 5)]
-      assert_called_with(@person.errors, :generate_message, call) do
+      call = [:title, :wrong_length, @person, generate_message_options.merge(count: 5)]
+      assert_called_with(ActiveModel::Error, :generate_message, call) do
         @person.valid?
         @person.errors.messages
       end
@@ -246,8 +246,8 @@ class I18nValidationTest < ActiveModel::TestCase
     test "validates_format_of on generated message #{name}" do
       person_class.validates_format_of :title, validation_options.merge(with: /\A[1-9][0-9]*\z/)
       @person.title = "72x"
-      call = [:title, :invalid, generate_message_options.merge(value: "72x")]
-      assert_called_with(@person.errors, :generate_message, call) do
+      call = [:title, :invalid, @person, generate_message_options.merge(value: "72x")]
+      assert_called_with(ActiveModel::Error, :generate_message, call) do
         @person.valid?
         @person.errors.messages
       end
@@ -258,8 +258,8 @@ class I18nValidationTest < ActiveModel::TestCase
     test "validates_inclusion_of on generated message #{name}" do
       person_class.validates_inclusion_of :title, validation_options.merge(in: %w(a b c))
       @person.title = "z"
-      call = [:title, :inclusion, generate_message_options.merge(value: "z")]
-      assert_called_with(@person.errors, :generate_message, call) do
+      call = [:title, :inclusion, @person, generate_message_options.merge(value: "z")]
+      assert_called_with(ActiveModel::Error, :generate_message, call) do
         @person.valid?
         @person.errors.messages
       end
@@ -270,8 +270,8 @@ class I18nValidationTest < ActiveModel::TestCase
     test "validates_inclusion_of using :within on generated message #{name}" do
       person_class.validates_inclusion_of :title, validation_options.merge(within: %w(a b c))
       @person.title = "z"
-      call = [:title, :inclusion, generate_message_options.merge(value: "z")]
-      assert_called_with(@person.errors, :generate_message, call) do
+      call = [:title, :inclusion, @person, generate_message_options.merge(value: "z")]
+      assert_called_with(ActiveModel::Error, :generate_message, call) do
         @person.valid?
         @person.errors.messages
       end
@@ -282,8 +282,8 @@ class I18nValidationTest < ActiveModel::TestCase
     test "validates_exclusion_of generated message #{name}" do
       person_class.validates_exclusion_of :title, validation_options.merge(in: %w(a b c))
       @person.title = "a"
-      call = [:title, :exclusion, generate_message_options.merge(value: "a")]
-      assert_called_with(@person.errors, :generate_message, call) do
+      call = [:title, :exclusion, @person, generate_message_options.merge(value: "a")]
+      assert_called_with(ActiveModel::Error, :generate_message, call) do
         @person.valid?
         @person.errors.messages
       end
@@ -294,8 +294,8 @@ class I18nValidationTest < ActiveModel::TestCase
     test "validates_exclusion_of using :within generated message #{name}" do
       person_class.validates_exclusion_of :title, validation_options.merge(within: %w(a b c))
       @person.title = "a"
-      call = [:title, :exclusion, generate_message_options.merge(value: "a")]
-      assert_called_with(@person.errors, :generate_message, call) do
+      call = [:title, :exclusion, @person, generate_message_options.merge(value: "a")]
+      assert_called_with(ActiveModel::Error, :generate_message, call) do
         @person.valid?
         @person.errors.messages
       end
@@ -306,8 +306,8 @@ class I18nValidationTest < ActiveModel::TestCase
     test "validates_numericality_of generated message #{name}" do
       person_class.validates_numericality_of :title, validation_options
       @person.title = "a"
-      call = [:title, :not_a_number, generate_message_options.merge(value: "a")]
-      assert_called_with(@person.errors, :generate_message, call) do
+      call = [:title, :not_a_number, @person, generate_message_options.merge(value: "a")]
+      assert_called_with(ActiveModel::Error, :generate_message, call) do
         @person.valid?
         @person.errors.messages
       end
@@ -318,8 +318,8 @@ class I18nValidationTest < ActiveModel::TestCase
     test "validates_numericality_of for :only_integer on generated message #{name}" do
       person_class.validates_numericality_of :title, validation_options.merge(only_integer: true)
       @person.title = "0.0"
-      call = [:title, :not_an_integer, generate_message_options.merge(value: "0.0")]
-      assert_called_with(@person.errors, :generate_message, call) do
+      call = [:title, :not_an_integer, @person, generate_message_options.merge(value: "0.0")]
+      assert_called_with(ActiveModel::Error, :generate_message, call) do
         @person.valid?
         @person.errors.messages
       end
@@ -330,8 +330,8 @@ class I18nValidationTest < ActiveModel::TestCase
     test "validates_numericality_of for :odd on generated message #{name}" do
       person_class.validates_numericality_of :title, validation_options.merge(only_integer: true, odd: true)
       @person.title = 0
-      call = [:title, :odd, generate_message_options.merge(value: 0)]
-      assert_called_with(@person.errors, :generate_message, call) do
+      call = [:title, :odd, @person, generate_message_options.merge(value: 0)]
+      assert_called_with(ActiveModel::Error, :generate_message, call) do
         @person.valid?
         @person.errors.messages
       end
@@ -342,8 +342,8 @@ class I18nValidationTest < ActiveModel::TestCase
     test "validates_numericality_of for :less_than on generated message #{name}" do
       person_class.validates_numericality_of :title, validation_options.merge(only_integer: true, less_than: 0)
       @person.title = 1
-      call = [:title, :less_than, generate_message_options.merge(value: 1, count: 0)]
-      assert_called_with(@person.errors, :generate_message, call) do
+      call = [:title, :less_than, @person, generate_message_options.merge(value: 1, count: 0)]
+      assert_called_with(ActiveModel::Error, :generate_message, call) do
         @person.valid?
         @person.errors.messages
       end