feat(proposals/test)-add test for additional speaker

Add test for additional speaker under uneditable condition.

src/proposals/tests/forms/test_additional_speaker.py

@@ -154,7 +154,13 @@ def test_additional_speaker_update_form_no_instance(form_class):
  'Additional speaker update form must be initialized with an instance.'
  )
 
-
+def test_additional_speaker_update_form_uneditable(additional_speaker):
+ form = AdditionalSpeakerSetStatusForm(additional_speaker)
+ """ 
+ Have to add something determine whether this form is editable
+ """
+ assert not form.is_valid()
+
 def test_additional_speaker_cancel_form(additional_speaker):
  form = AdditionalSpeakerCancelForm(instance=additional_speaker)
  assert list(form.fields) == ['cancelled']