PyStateMachine

Python State Machine

Introduction

PyStateMachine is a Framework that support state machines in Python

Requirements

Python3

How to Run

How do we import the framework?

Insure that Python3 is installed:
- https://www.python.org/downloads/
Install the PyStateMachines framework
- pip3 install PyStateMachines

Example

After framework is installed, import and create a small example. Create xml file from sample with the State machine states.

myStateMachine.xml

<?xml version="1.0"?>
<x:States xmlns:x="pystatemachine:sm">
    <State>
        <Name>State1</Name>
        <Event>
            <Name>ToState2</Name>
            <ToState>State2</ToState>
        </Event>
    </State>
    <State>
        <Name>State2</Name>
        <Event>
            <Name>ToState3</Name>
            <ToState>State3</ToState>
        </Event>
    </State>
    <State>
        <Name>State3</Name>
        <Event>
            <Name>ToState1</Name>
            <ToState>State1</ToState>
        </Event>
    </State>
    <Initial_State>State1</Initial_State>
</x:States>

Create Python Script to run state machine pyStateMachine.py

# importing necessary packages
from StateMachine import StateMachine

"""Test StateMachine"""
sm = StateMachine("myStateMachine.xml")
sm.LoadStateMachine()

# print initial state
print(sm.get_current_state())  # current_state == State1

sm.InjectEvent("ToState2")
print(sm.get_current_state())  # current_state == State2

sm.InjectEvent("ToState3")
print(sm.get_current_state())  # current_state == State3

sm.InjectEvent("ToState1")
print(sm.get_current_state())  # current_state == State1

run Python script to execute state machine

python pyStateMachine.py

pyStateMachineUnitTest.py

## Test Suite
#  importing necessary packages
from StateMachine import StateMachine
import unittest

class TestBaseStateMachine(unittest.TestCase):
    """Test state machine using various samples"""

# test all valid state transitions
    def test1(self):
        """Test Statemachine"""
        sm = StateMachine("myStateMachine.xml")
        sm.LoadStateMachine()
        self.assertEqual(sm.get_current_state(), "State1", "Should be State1")
        # OK Event
        sm.InjectEvent("ToState2")
        self.assertEqual(sm.get_current_state(), "State2", "Should be State2")
        # OK Event
        sm.InjectEvent("ToState3")
        self.assertEqual(sm.get_current_state(), "State3", "Should be State3")
        # OK Event
        sm.InjectEvent("ToState1")
        self.assertEqual(sm.get_current_state(), "State1", "Should be State1")

# test invalid State1 transitions
    def test2(self):
        """Test Statemachine"""
        sm = StateMachine("myStateMachine.xml")
        sm.LoadStateMachine()
        self.assertEqual(sm.get_current_state(), "State1", "Should be State1")
        # Invalid transition
        sm.InjectEvent("ToState3")
        self.assertEqual(sm.get_current_state(), "State1", "Should be State1")

# test invalid State2 transitions
    def test3(self):
        """Test Statemachine"""
        sm = StateMachine("myStateMachine.xml")
        sm.LoadStateMachine()
        self.assertEqual(sm.get_current_state(), "State1", "Should be State1")
        # OK Event
        sm.InjectEvent("ToState2")
        self.assertEqual(sm.get_current_state(), "State2", "Should be State2")
        # Invalid transition
        sm.InjectEvent("ToState1")
        self.assertEqual(sm.get_current_state(), "State2", "Should be State2")

# test invalid State3 transitions
    def test4(self):
        """Test Statemachine"""
        sm = StateMachine("myStateMachine.xml")
        sm.LoadStateMachine()
        self.assertEqual(sm.get_current_state(), "State1", "Should be State1")
        # OK Event
        sm.InjectEvent("ToState2")
        self.assertEqual(sm.get_current_state(), "State2", "Should be State2")
        # OK Event
        sm.InjectEvent("ToState3")
        self.assertEqual(sm.get_current_state(), "State3", "Should be State3")
        # Invalid transition
        sm.InjectEvent("ToState2")
        self.assertEqual(sm.get_current_state(), "State3", "Should be State3")

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

run unit tests