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Streaming & messaging

Kafka-style pub/sub, event consumers, async pipelines, and message-driven workflows.

5 matches

How to Implement Publish-Subscribe Fanout with Multiple Subscribers in Python

Create a simple publish-subscribe system in Python that broadcasts messages to multiple subscriber callbacks for a given topic.

pubsub messaging events

Python

import time

class PubSub:
    def __init__(self):
        self.subscribers = {}

    def subscribe(self, topic, callback):
        if topic not in self.subscribers:
            self.subscribers[topic] = []
        self.subscribers[topic].append(callback)

    def publish(self, topic, message):
        if topic in sel…

14 0 Open

Streaming & messaging easy

How to Mock Kafka Topic Partitions with a Python dict of lists

Mocks a Kafka topic and its partitions using a defaultdict of lists to simulate message production, consumption, and per-partition counts.

kafka mock partitions

Python

from collections import defaultdict

class KafkaTopicPartitionMock:
    """A simple mock for Kafka topic-partition assignment using dict of lists."""

    def __init__(self, topic):
        self.topic = topic
        self.partitions = defaultdict(list)  # partition_id -> list of messages

    def produce(self, message…

15 0 Open

Streaming & messaging medium

How to Mock NATS Subject Hierarchies with Wildcards in Python

Build a lightweight NATS-style pub/sub mock that matches subject hierarchies with '*' and '>' wildcards for tests or prototypes.

nats pubsub wildcards

Python

# Mock a simplified NATS subject hierarchy with wildcard matching
# Supports: exact match, '*' (single token), '>' (tail wildcard)

class NATSSubjectMock:
    def __init__(self):
        self.subscriptions = {}  # subject -> list of callbacks

    def subscribe(self, subject, callback):
        self.subscriptions.setd…

13 0 Open

Streaming & messaging medium

How to Mock Offset Commit Auto vs Manual in Python

Demonstrates a Kafka-style offset commit function with auto/manual modes and tests it using unittest.mock.patch.

unittest mocking kafka

Python

from unittest.mock import Mock, patch

def commit_offsets(topic_partition_offsets, auto_commit=False):
    """Manually commit offsets or simulate auto-commit."""
    if auto_commit:
        print(f"Auto-committing offsets: {topic_partition_offsets}")
        return {"status": "auto_committed"}
    
    print(f"Manuall…

15 0 Open

Streaming & messaging easy

Redis Pub/Sub Channel Subscribe Mock in Python

A lightweight in-memory mock of Redis pub/sub that lets you subscribe to channels, publish messages, and verify handler behavior in tests without a real Redis server.

redis pubsub testing

Python

class MockRedisPubSub:
    def __init__(self):
        self.channels = {}

    def subscribe(self, channel):
        if channel not in self.channels:
            self.channels[channel] = []
        return self.channels[channel]

    def publish(self, channel, message):
        if channel in self.channels:
            …

11 0 Open

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