Add deprecation for doing `attribute_method_suffix ''`

1 files changed, 11 insertions, 6 deletions

diff --git a/activemodel/test/cases/attribute_methods_test.rb b/activemodel/test/cases/attribute_methods_test.rb
index 95a7098ba4..61ff5fca7a 100644
--- a/activemodel/test/cases/attribute_methods_test.rb
+++ b/activemodel/test/cases/attribute_methods_test.rb
@@ -3,8 +3,6 @@ require 'cases/helper'
 class ModelWithAttributes
   include ActiveModel::AttributeMethods
 
-  attribute_method_suffix ''
-
   class << self
     define_method(:bar) do
       'original bar'
@@ -39,8 +37,6 @@ end
 class ModelWithAttributesWithSpaces
   include ActiveModel::AttributeMethods
 
-  attribute_method_suffix ''
-
   def attributes
     { :'foo bar' => 'value of foo bar'}
   end
@@ -54,8 +50,6 @@ end
 class ModelWithWeirdNamesAttributes
   include ActiveModel::AttributeMethods
 
-  attribute_method_suffix ''
-
   class << self
     define_method(:'c?d') do
       'original c?d'
@@ -146,4 +140,15 @@ class AttributeMethodsTest < ActiveModel::TestCase
     assert_equal 'bar', m.foo
     assert_equal 'bar', m.foo_test
   end
+
+  test 'explicitly specifying an empty prefix/suffix is deprecated' do
+    klass = Class.new(ModelWithAttributes)
+
+    assert_deprecated { klass.attribute_method_suffix '' }
+    assert_deprecated { klass.attribute_method_prefix '' }
+
+    klass.define_attribute_methods([:foo])
+
+    assert_equal 'value of foo', klass.new.foo
+  end
 end