ensure_state_may_transition_to! to actually check if attribute can tr…

…ansition

lib/state_machine_enum.rb

@@ -114,6 +114,7 @@ def state_machine_enum(attribute_name, **options_for_enum)
         define_method(:"ensure_#{attribute_name}_may_transition_to!") do |next_state|
           val = self[attribute_name]
           raise InvalidState, "#{attribute_name} already is #{val.inspect}" if next_state.to_s == val
+          raise InvalidState, "#{attribute_name} may not transition from #{val.inspect} to #{next_state.inspect}" unless collector.may_transition?(val, next_state)
         end
 
         define_method(:"#{attribute_name}_may_transition_to?") do |next_state|

test/test_state_machine_enum.rb

@@ -40,10 +40,11 @@ def test_ensure_state_may_transition_to!
     assert_nil u.ensure_state_may_transition_to!(:banned)
 
     assert_raises(StateMachineEnum::InvalidState) { u.ensure_state_may_transition_to!("active") }
-    assert_raises(StateMachineEnum::InvalidState) { u.ensure_state_may_transition_to!(:active) }
+    error = assert_raises(StateMachineEnum::InvalidState) { u.ensure_state_may_transition_to!(:active) }
+    assert_equal("state already is \"active\"", error.message)
 
-    # TODO: This method will not actually check if state can transition to the target state, it only verifies that this is not a current state.
-    # assert_raises(StateMachineEnum::InvalidState) { u.ensure_state_may_transition_to!(:registered) }
+    error = assert_raises(StateMachineEnum::InvalidState) { u.ensure_state_may_transition_to!(:registered) }
+    assert_equal("state may not transition from \"active\" to :registered", error.message)
   end
 
   def test_ensure_state_one_of!