How to Mock MQTT Topic Subscriptions with QoS in Python

import time
from collections import defaultdict

class MockMQTTClient:
    def __init__(self):
        self.subscriptions = defaultdict(list)
        self.messages = []
    
    def subscribe(self, topic, qos=0):
        self.subscriptions[topic].append(qos)
        print(f"Subscribed to '{topic}' with QoS {qos}")
    
    def publish(self, topic, payload):
        print(f"Publishing '{payload}' to '{topic}'")
        for sub_topic, qos_list in self.subscriptions.items():
            if sub_topic == topic or topic.startswith(sub_topic.rstrip('/') + '/'):
                for qos in qos_list:
                    delivery = f"QoS {qos}: {payload}"
                    self.messages.append((topic, delivery))
                    print(f"  Delivered: {delivery}")

def main():
    client = MockMQTTClient()
    
    # Subscribe to various topics with different QoS levels
    client.subscribe("sensors/temperature", qos=1)
    client.subscribe("sensors/humidity", qos=2)
    client.subscribe("sensors/#", qos=0)  # wildcard subscription
    
    print("\n--- Publishing messages ---")
    client.publish("sensors/temperature", "23.5°C")
    client.publish("sensors/humidity", "45%")
    client.publish("sensors/pressure", "1013 hPa")
    
    print("\n--- Message log ---")
    for idx, (topic, msg) in enumerate(client.messages, 1):
        print(f"{idx}. Topic: {topic} | {msg}")

if __name__ == "__main__":
    main()