Python Code
Samples
Copy-ready Python snippets by topic and difficulty — short, focused, and runnable in the browser editor.
How to Mock a semantic-release Changelog in Python
This Python code simulates a semantic-release changelog generator, grouping commits by type and formatting them into a markdown changelog.
import json
from datetime import datetime
class SemanticReleaseChangelog:
def __init__(self, version, commits):
self.version = version
self.commits = commits
self.release_date = datetime.now().isoformat()
def generate_changelog(self):
grouped = {}
for commit in self.c…Mock Unit of Work commit and rollback in Python
Verify that a Unit of Work pattern commits on success and rolls back on failure using unittest.mock in Python.
from unittest import mock
class UnitOfWork:
def __init__(self):
self.committed = False
self.rolled_back = False
def commit(self):
self.committed = True
print("Commit executed")
def rollback(self):
self.rolled_back = True
print("Rollback executed")
def b…Batch Consume Process Commit Pattern in Python
A mock batch processor that accumulates items in a queue, processes full batches, commits successful or failed results, and flushes remaining items.
import random
import threading
import time
from collections import deque
class MockBatchProcessor:
def __init__(self, process_func, commit_func, batch_size=5):
self.queue = deque()
self.batch_size = batch_size
self.process_func = process_func
self.commit_func = commit_func
de…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.
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…Kafka Consumer Poll Loop Mock in Python
Simulate a Kafka consumer poll loop with a mock class, process messages in batches, and commit offsets to understand streaming consumption patterns.
import time
class MockKafkaConsumer:
def __init__(self, topic, messages):
self.topic = topic
self.messages = list(messages)
self.position = 0
def poll(self, timeout_ms=100):
if self.position >= len(self.messages):
time.sleep(timeout_ms / 1000)
return []…Python Redis WATCH optimistic lock mock
A MockRedis class that simulates WATCH/MULTI/EXEC transactions with optimistic locking to detect concurrent modifications before committing.
import time
import threading
class MockRedis:
def __init__(self):
self.data = {}
self.watched = {}
self.lock = threading.Lock()
def get(self, key):
return self.data.get(key)
def set(self, key, value):
self.data[key] = value
def watch(self, *keys):
wi…Mock a Two-Phase Commit Coordinator in Python
Simulates a two-phase commit protocol where a coordinator asks participants to prepare, then commits or aborts based on unanimous readiness.
import random
import time
from typing import Dict, List
class TwoPhaseCommitCoordinator:
def __init__(self, participants: List[str]):
self.participants = participants
self.participant_state: Dict[str, bool] = {}
def prepare(self) -> bool:
print("[Coordinator] Phase 1: Prepare")
…How to Implement a Two-Phase Commit Mock in Python
Simulate a distributed two-phase commit with prepare, commit, and abort phases, including deterministic failure injection for testing.
import random
from dataclasses import dataclass
from typing import Dict, List, Optional
@dataclass
class Transaction:
tx_id: int
data: Dict[str, str]
class TwoPhaseCommitMock:
"""Simple two-phase commit mock with prepare and commit phases."""
def __init__(self) -> None:
self.prepared: List…Delta Lake ACID Transaction Log Mock in Python
Simulates Delta Lake's transactional log with JSON files for atomic commits, versioned operations, and crash recovery
import json
import time
from pathlib import Path
class DeltaLog:
def __init__(self, path):
self.log_dir = Path(path)
self.log_dir.mkdir(parents=True, exist_ok=True)
self.version = 0
def _write_txn(self, action, payload):
txn = {
"version": self.version,
…How to Simulate Distributed Transactions in Python with a Mock
Model distributed transaction behavior with a mock Transaction class that supports commit, rollback, and failure simulation.
class Transaction:
def __init__(self, id):
self.id = id
self.operations = []
self.committed = False
def add_operation(self, op, data):
self.operations.append((op, data))
def commit(self):
if not self.operations:
raise ValueError("No operations to commit…How to mock batch commit of transactions in Python
Simulate a transaction batch writer with commit, rollback, and summary logic to test database write patterns without a real database.
import json
from datetime import datetime, timezone
class TransactionBatch:
def __init__(self):
self.pending = []
self.committed = []
self._log = []
def add(self, operation):
self.pending.append(operation)
def commit(self):
if not self.pending:
return …Two Phase Commit Cross Shard Mock in Python
Simulates a two-phase commit across shards with failure handling to demonstrate distributed transaction coordination in Python.
"""Mock cross-shard two-phase commit with caution handling."""
class Shard:
def __init__(self, name):
self.name = name
self.prepared = False
self.committed = False
self.aborted = False
def prepare(self):
# Simulate potential failure (1 in 3 chance on third shard)
…Automate Semantic Versioning with Conventional Commits in Python
Automatically bump a semantic version based on conventional commit messages (feat, fix, BREAKING CHANGE) and write the new version to a file.
import re
from pathlib import Path
def get_next_version(current: str, commit_messages: list[str]) -> str:
"""Return the next semantic version based on conventional commit messages."""
major, minor, patch = map(int, current.split("."))
if any(msg.startswith("BREAKING CHANGE") for msg in commit_messages):
…Browse by section
Each section groups closely related Python snippets.
Guide: free Python code samples library
Copy-ready Python snippets for learners and developers
PythonSkillset code samples are short, focused examples organised by topic and difficulty. Every snippet is server-rendered HTML — readable by search engines and easy to copy. Open any sample, read the notes, copy the code, then press Try in editor to run it in the browser with Pyodide.
How to use this library
- Pick a topic section — strings, lists, files, functions, and more
- Open a sample, read How it works, and copy the code block
- Run it in the IDE, tweak values, then take a related quiz or tutorial lesson
Samples vs tutorials and challenges
Samples are quick reference — one concept per page. For step-by-step teaching, use our Python tutorials. To test yourself, try quizzes or coding challenges. Clean up style with the Python formatter.