Added test for obj.errors.as_json

activemodel/test/cases/errors_test.rb

@@ -102,4 +102,15 @@ class ErrorsTest < ActiveModel::TestCase
     assert_equal "name can not be blank", person.errors.full_message(:name, "can not be blank")
   end
 
+  test 'should return a JSON hash representation of the errors' do
+    person = Person.new
+    person.errors.add(:name, "can not be blank")
+    person.errors.add(:name, "can not be nil")
+    person.errors.add(:email, "is invalid")
+    hash = person.errors.as_json
+    assert_equal ["can not be blank", "can not be nil"], hash[:name]
+    assert_equal ["is invalid"], hash[:email]
+  end
+
 end
+