2 files changed, 79 insertions, 0 deletions
diff --git a/activemodel/test/cases/railtie_test.rb b/activemodel/test/cases/railtie_test.rb
index ff5022e960..ab60285e2a 100644
--- a/activemodel/test/cases/railtie_test.rb
+++ b/activemodel/test/cases/railtie_test.rb
@@ -31,4 +31,24 @@ class RailtieTest < ActiveModel::TestCase
 
     assert_equal true, ActiveModel::SecurePassword.min_cost
   end
+
+  test "i18n full message defaults to false" do
+    @app.initialize!
+
+    assert_equal false, ActiveModel::Errors.i18n_full_message
+  end
+
+  test "i18n full message can be disabled" do
+    @app.config.active_model.i18n_full_message = false
+    @app.initialize!
+
+    assert_equal false, ActiveModel::Errors.i18n_full_message
+  end
+
+  test "i18n full message can be enabled" do
+    @app.config.active_model.i18n_full_message = true
+    @app.initialize!
+
+    assert_equal true, ActiveModel::Errors.i18n_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 9cfe189d0e..1c62e750de 100644
--- a/activemodel/test/cases/validations/i18n_validation_test.rb
+++ b/activemodel/test/cases/validations/i18n_validation_test.rb
@@ -12,6 +12,9 @@ class I18nValidationTest < ActiveModel::TestCase
     I18n.load_path.clear
     I18n.backend = I18n::Backend::Simple.new
     I18n.backend.store_translations("en", errors: { messages: { custom: nil } })
+
+    @original_i18n_full_message = ActiveModel::Errors.i18n_full_message
+    ActiveModel::Errors.i18n_full_message = true
   end
 
   def teardown
@@ -19,6 +22,7 @@ class I18nValidationTest < ActiveModel::TestCase
     I18n.load_path.replace @old_load_path
     I18n.backend = @old_backend
     I18n.backend.reload!
+    ActiveModel::Errors.i18n_full_message = @original_i18n_full_message
   end
 
   def test_full_message_encoding
@@ -42,6 +46,61 @@ class I18nValidationTest < ActiveModel::TestCase
     assert_equal ["Field Name empty"], @person.errors.full_messages
   end
 
+  def test_errors_full_messages_doesnt_use_attribute_format_without_config
+    ActiveModel::Errors.i18n_full_message = false
+
+    I18n.backend.store_translations("en", activemodel: {
+      errors: { models: { person: { attributes: { name: { format: "%{message}" } } } } } })
+
+    person = Person.new
+    assert_equal "Name cannot be blank", person.errors.full_message(:name, "cannot be blank")
+    assert_equal "Name test cannot be blank", person.errors.full_message(:name_test, "cannot be blank")
+  end
+
+  def test_errors_full_messages_uses_attribute_format
+    ActiveModel::Errors.i18n_full_message = true
+
+    I18n.backend.store_translations("en", activemodel: {
+      errors: { models: { person: { attributes: { name: { format: "%{message}" } } } } } })
+
+    person = Person.new
+    assert_equal "cannot be blank", person.errors.full_message(:name, "cannot be blank")
+    assert_equal "Name test cannot be blank", person.errors.full_message(:name_test, "cannot be blank")
+  end
+
+  def test_errors_full_messages_uses_model_format
+    ActiveModel::Errors.i18n_full_message = true
+
+    I18n.backend.store_translations("en", activemodel: {
+      errors: { models: { person: { format: "%{message}" } } } })
+
+    person = Person.new
+    assert_equal "cannot be blank", person.errors.full_message(:name, "cannot be blank")
+    assert_equal "cannot be blank", person.errors.full_message(:name_test, "cannot be blank")
+  end
+
+  def test_errors_full_messages_uses_deeply_nested_model_attributes_format
+    ActiveModel::Errors.i18n_full_message = true
+
+    I18n.backend.store_translations("en", activemodel: {
+      errors: { models: { 'person/contacts/addresses': { attributes: { street: { format: "%{message}" } } } } } })
+
+    person = Person.new
+    assert_equal "cannot be blank", person.errors.full_message(:'contacts/addresses.street', "cannot be blank")
+    assert_equal "Contacts/addresses country cannot be blank", person.errors.full_message(:'contacts/addresses.country', "cannot be blank")
+  end
+
+  def test_errors_full_messages_uses_deeply_nested_model_model_format
+    ActiveModel::Errors.i18n_full_message = true
+
+    I18n.backend.store_translations("en", activemodel: {
+      errors: { models: { 'person/contacts/addresses': { format: "%{message}" } } } })
+
+    person = Person.new
+    assert_equal "cannot be blank", person.errors.full_message(:'contacts/addresses.street', "cannot be blank")
+    assert_equal "cannot be blank", person.errors.full_message(:'contacts/addresses.country', "cannot be blank")
+  end
+
   # ActiveModel::Validations
 
   # A set of common cases for ActiveModel::Validations message generation that