openstack
/
automaton
Code Issues Proposed changes

Disallow adding transitions from terminal states 

Terminal states are by there very nature terminal and can not
have transitions to other states on any kind of event so on add
make sure we disallow those types of transitions to even be
created in the first place.

Change-Id: I70321e9482a0d053a8cb0bc89a766b5fbc82f69e
This commit is contained in:
Joshua Harlow 2015-06-24 14:23:11 -07:00
parent 59d34fa3ed
commit 89656ae907
2 changed files with 10 additions and 0 deletions
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4
automaton/machines.py
View File

@ -190,6 +190,10 @@ class FiniteMachine(object):
raise excp.NotFound("Can not add a transition on event '%s' that"
" ends in a undefined state '%s'"
% (event, end))
if self._states[start]['terminal']:
raise excp.InvalidState("Can not add a transition on event '%s'"
" that starts in the terminal state '%s'"
% (event, start))
self._transitions[start][event] = _Jump(end,
self._states[end]['on_enter'],
self._states[start]['on_exit'])

6
automaton/tests/test_fsm.py
View File

@ -60,6 +60,12 @@ class FSMTest(testcase.TestCase):
m.add_state('unknown')
self.assertIn('unknown', m)
def test_no_add_transition_terminal(self):
m = self._create_fsm('up')
m.add_state('down', terminal=True)
self.assertRaises(excp.InvalidState,
m.add_transition, 'down', 'up', 'jump')
def test_duplicate_state(self):
m = self._create_fsm('unknown')
self.assertRaises(excp.Duplicate, m.add_state, 'unknown')