1 files changed, 7 insertions, 0 deletions
diff --git a/activemodel/test/cases/errors_test.rb b/activemodel/test/cases/errors_test.rb
index a5ac055033..26ba6ba4fb 100644
--- a/activemodel/test/cases/errors_test.rb
+++ b/activemodel/test/cases/errors_test.rb
@@ -128,6 +128,13 @@ class ErrorsTest < ActiveModel::TestCase
     assert !person.errors.include?(:foo)
   end
 
+  test "include? does not add a key to messages hash" do
+    person = Person.new
+    person.errors.include?(:foo)
+
+    assert_not person.errors.messages.key?(:foo)
+  end
+
   test "adding errors using conditionals with Person#validate!" do
     person = Person.new
     person.validate!