test_hsm.py

#!/usr/bin/env python
from hsm import HierachicalStateMachine, UnsupportedMessageType,\
    UnsupportedState, UnsupportedTransition, Active, Standby, Suspect, Failed
from sys import version_info

if version_info < (2, 7):  # pragma: no cover
    import unittest2 as unittest
else:
    import unittest

try:
    from unittest.mock import patch
except ImportError:
    from mock import patch


class HsmMethodTest(unittest.TestCase):

    @classmethod
    def setUpClass(cls):
        cls.hsm = HierachicalStateMachine()

    def test_initial_state_shall_be_standby(cls):
        cls.assertEqual(isinstance(cls.hsm._current_state, Standby), True)

    def test_unsupported_state_shall_raise_exception(cls):
        with cls.assertRaises(UnsupportedState) as context:
            cls.hsm._next_state('missing')

    def test_unsupported_message_type_shall_raise_exception(cls):
        with cls.assertRaises(UnsupportedMessageType) as context:
            cls.hsm.on_message('trigger')

    def test_calling_next_state_shall_change_current_state(cls):
        cls.hsm._current_state = Standby  # initial state
        cls.hsm._next_state('active')
        cls.assertEqual(isinstance(cls.hsm._current_state, Active), True)
        cls.hsm._current_state = Standby(cls.hsm)  # initial state

    def test_method_perform_switchover_shall_return_specifically(cls):
        """ Exemplary HierachicalStateMachine method test.
        (here: _perform_switchover()). Add additional test cases... """
        return_value = cls.hsm._perform_switchover()
        expected_return_value = 'perform switchover'
        cls.assertEqual(return_value, expected_return_value)


class StandbyStateTest(unittest.TestCase):
    """ Exemplary 2nd level state test class (here: Standby state). Add missing
    state test classes... """

    @classmethod
    def setUpClass(cls):
        cls.hsm = HierachicalStateMachine()

    def setUp(cls):
        cls.hsm._current_state = Standby(cls.hsm)

    def test_given_standby_on_message_switchover_shall_set_active(cls):
        cls.hsm.on_message('switchover')
        cls.assertEqual(isinstance(cls.hsm._current_state, Active), True)

    def test_given_standby_on_message_switchover_shall_call_hsm_methods(cls):
        with patch.object(cls.hsm, '_perform_switchover') as mock_perform_switchover,\
             patch.object(cls.hsm, '_check_mate_status') as mock_check_mate_status,\
             patch.object(cls.hsm, '_send_switchover_response') as mock_send_switchover_response,\
             patch.object(cls.hsm, '_next_state') as mock_next_state:
            cls.hsm.on_message('switchover')
            cls.assertEqual(mock_perform_switchover.call_count, 1)
            cls.assertEqual(mock_check_mate_status.call_count, 1)
            cls.assertEqual(mock_send_switchover_response.call_count, 1)
            cls.assertEqual(mock_next_state.call_count, 1)

    def test_given_standby_on_message_fault_trigger_shall_set_suspect(cls):
        cls.hsm.on_message('fault trigger')
        cls.assertEqual(isinstance(cls.hsm._current_state, Suspect), True)

    def test_given_standby_on_message_diagnostics_failed_shall_raise_exception_and_keep_in_state(cls):
        with cls.assertRaises(UnsupportedTransition) as context:
            cls.hsm.on_message('diagnostics failed')
        cls.assertEqual(isinstance(cls.hsm._current_state, Standby), True)

    def test_given_standby_on_message_diagnostics_passed_shall_raise_exception_and_keep_in_state(cls):
        with cls.assertRaises(UnsupportedTransition) as context:
            cls.hsm.on_message('diagnostics passed')
        cls.assertEqual(isinstance(cls.hsm._current_state, Standby), True)

    def test_given_standby_on_message_operator_inservice_shall_raise_exception_and_keep_in_state(cls):
        with cls.assertRaises(UnsupportedTransition) as context:
            cls.hsm.on_message('operator inservice')
        cls.assertEqual(isinstance(cls.hsm._current_state, Standby), True)


if __name__ == "__main__":
    unittest.main()