test stack error

 ERROR (0:00:00.175) test_should_create_a_session
          ActiveModel::ForbiddenAttributesError
        @ /home/jeff/.rvm/gems/ruby-2.1.1/gems/activemodel-4.0.3/lib/active_model/forbidden_attributes_protection.rb:21:in `sanitize_for_mass_assignment'
          /home/jeff/.rvm/gems/ruby-2.1.1/gems/activerecord-4.0.3/lib/active_record/attribute_assignment.rb:21:in `assign_attributes'
          /home/jeff/.rvm/gems/ruby-2.1.1/gems/activerecord-4.0.3/lib/active_record/core.rb:460:in `init_attributes'
          /home/jeff/.rvm/gems/ruby-2.1.1/gems/activerecord-4.0.3/lib/active_record/core.rb:185:in `initialize'
          /home/jeff/.rvm/gems/ruby-2.1.1/gems/activerecord-4.0.3/lib/active_record/inheritance.rb:27:in `new'
          /home/jeff/.rvm/gems/ruby-2.1.1/gems/activerecord-4.0.3/lib/active_record/inheritance.rb:27:in `new'
          app/controllers/a_sessions_controller.rb:21:in `create'
          /home/jeff/.rvm/gems/ruby-2.1.1/gems/actionpack-4.0.3/lib/abstract_controller/base.rb:189:in `process_action'
          /home/jeff/.rvm/gems/ruby-2.1.1/gems/actionpack-4.0.3/lib/action_controller/metal/rendering.rb:10:in `process_action'
          /home/jeff/.rvm/gems/ruby-2.1.1/gems/actionpack-4.0.3/lib/abstract_controller/callbacks.rb:18:in `block in process_action'
          /home/jeff/.rvm/gems/ruby-2.1.1/gems/activesupport-4.0.3/lib/active_support/callbacks.rb:373:in `_run__2676339135465314787__process_action__callbacks'
          /home/jeff/.rvm/gems/ruby-2.1.1/gems/activesupport-4.0.3/lib/active_support/callbacks.rb:80:in `run_callbacks'
          /home/jeff/.rvm/gems/ruby-2.1.1/gems/actionpack-4.0.3/lib/abstract_controller/callbacks.rb:17:in `process_action'
          /home/jeff/.rvm/gems/ruby-2.1.1/gems/actionpack-4.0.3/lib/action_controller/metal/rescue.rb:29:in `process_action'
          /home/jeff/.rvm/gems/ruby-2.1.1/gems/actionpack-4.0.3/lib/action_controller/metal/instrumentation.rb:31:in `block in process_action'
          /home/jeff/.rvm/gems/ruby-2.1.1/gems/activesupport-4.0.3/lib/active_support/notifications.rb:159:in `block in instrument'
          /home/jeff/.rvm/gems/ruby-2.1.1/gems/activesupport-4.0.3/lib/active_support/notifications/instrumenter.rb:20:in `instrument'
          /home/jeff/.rvm/gems/ruby-2.1.1/gems/activesupport-4.0.3/lib/active_support/notifications.rb:159:in `instrument'
          /home/jeff/.rvm/gems/ruby-2.1.1/gems/actionpack-4.0.3/lib/action_controller/metal/instrumentation.rb:30:in `process_action'
          /home/jeff/.rvm/gems/ruby-2.1.1/gems/activerecord-4.0.3/lib/active_record/railties/controller_runtime.rb:18:in `process_action'
          /home/jeff/.rvm/gems/ruby-2.1.1/gems/actionpack-4.0.3/lib/abstract_controller/base.rb:136:in `process'
          /home/jeff/.rvm/gems/ruby-2.1.1/gems/actionpack-4.0.3/lib/abstract_controller/rendering.rb:44:in `process'
          /home/jeff/.rvm/gems/ruby-2.1.1/gems/actionpack-4.0.3/lib/action_controller/test_case.rb:569:in `process'
          /home/jeff/.rvm/gems/ruby-2.1.1/gems/actionpack-4.0.3/lib/action_controller/test_case.rb:64:in `process'
          /home/jeff/.rvm/gems/ruby-2.1.1/gems/actionpack-4.0.3/lib/action_controller/test_case.rb:475:in `post'
          test/controllers/a_sessions_controller_test.rb:35:in `block (2 levels) in <class:ASessionsControllerTest>'
          /home/jeff/.rvm/gems/ruby-2.1.1/gems/activesupport-4.0.3/lib/active_support/testing/assertions.rb:71:in `assert_difference'
          test/controllers/a_sessions_controller_test.rb:34:in `block in <class:ASessionsControllerTest>'
          /home/jeff/.rvm/rubies/ruby-2.1.1/lib/ruby/2.1.0/minitest/unit.rb:1265:in `run'
          /home/jeff/.rvm/rubies/ruby-2.1.1/lib/ruby/2.1.0/minitest/unit.rb:884:in `_run_anything'
          /home/jeff/.rvm/rubies/ruby-2.1.1/lib/ruby/2.1.0/minitest/unit.rb:1092:in `run_tests'
          /home/jeff/.rvm/rubies/ruby-2.1.1/lib/ruby/2.1.0/minitest/unit.rb:1079:in `block in _run'
          /home/jeff/.rvm/rubies/ruby-2.1.1/lib/ruby/2.1.0/minitest/unit.rb:1078:in `each'
          /home/jeff/.rvm/rubies/ruby-2.1.1/lib/ruby/2.1.0/minitest/unit.rb:1078:in `_run'
          /home/jeff/.rvm/rubies/ruby-2.1.1/lib/ruby/2.1.0/minitest/unit.rb:1066:in `run'
          /home/jeff/.rvm/rubies/ruby-2.1.1/lib/ruby/2.1.0/minitest/unit.rb:802:in `block in autorun'