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Unit of Work Pattern: Track Changes, Commit, and Rollback in Python
This code defines a UnitOfWork class that tracks operations (add) and supports commit to apply changes and rollback to revert them, using a dataclass-based logger.
from dataclasses import dataclass, field
from typing import Any, Callable, List, Tuple
@dataclass
class UnitOfWork:
log: List[Tuple[str, Callable, tuple, dict]] = field(default_factory=list)
def track(self, operation: str, fn: Callable, *args, **kwargs):
self.log.append((operation, fn, args, kwargs)…Find the Commit That Introduced a String in Git History Using Python
Use git log -S with Python subprocess to find the earliest commit that introduced a specific string across your repository history.
import subprocess
import sys
def find_introducing_commit(repo_path: str, search_string: str, file_glob: str = "*") -> str:
"""Find the first commit that introduced a given string in a git repository."""
result = subprocess.run(
["git", "-C", repo_path, "log", "--all", "--oneline", "-S", search_string…Generate CHANGELOG from Conventional Commits in Python
Parse your git log for conventional commits (feat, fix) and produce a simple Markdown CHANGELOG with grouped features and bug fixes.
import subprocess
import re
import sys
from collections import OrderedDict
CONVENTIONAL_COMMIT = re.compile(
r"^(?P<type>feat|fix|chore|docs|refactor|perf|test|build|ci|style)(?:\((?P<scope>[^)]+)\))?: (?P<description>.+)"
)
def get_git_log():
return subprocess.run(
["git", "log", "--format=%s"],
…Generate Release Notes Markdown from PR Titles in Python
Generate structured Markdown release notes from a list of pull request titles using conventional commit types.
import json
from datetime import datetime, timezone
PRS = [
{"title": "feat: add user login", "number": 12, "merged_at": "2025-01-10"},
{"title": "fix: resolve payment timeout", "number": 13, "merged_at": "2025-01-11"},
{"title": "chore: bump dependencies", "number": 14, "merged_at": "2025-01-12"},
{"…How to Format Git Patch Series as an MBOX File in Python
Generate a patch-series mbox file from commit metadata with numbered [PATCH nnn/nnn] subjects and a Git-style footer.
import re
from pathlib import Path
def format_patch_series_mbox(commits, output_path="series.mbox"):
entries = []
for idx, commit in enumerate(commits, start=1):
subject = commit["subject"]
author = commit["author"]
email = commit["email"]
date = commit["date"]
body = …How to Generate Release Notes from Git Commit Messages in Python
This script fetches recent Git commit messages using conventional commit prefixes (feat, fix, etc.), categorizes them, and prints formatted release notes with today's date.
import subprocess
import re
from datetime import datetime
def get_git_log(since_tag="HEAD~10", format_str="%s"):
"""Retrieve commit messages from git log."""
try:
result = subprocess.run(
["git", "log", f"--since={since_tag}", f"--format={format_str}"],
capture_output=True,
…How to Make a Git Commit Heatmap by Hour in Python
Parse a git log output and count commits by weekday and hour, then print a compact heatmap table.
import re
from collections import Counter
from datetime import datetime
def parse_commits(log_text):
"""Parse git log lines and count commits by (weekday, hour)."""
pattern = re.compile(r"^Date:\s+(.+)$")
counts = Counter()
for line in log_text.splitlines():
match = pattern.match(line)
…How to Mock Git Pre-commit Hooks (black and ruff) in Python
Mock subprocess to test black and ruff pre-commit commands without actually running them, verifying exit codes.
import sys
import subprocess
from unittest.mock import patch
def run_hook(command: list[str]) -> int:
with patch("subprocess.run") as mock_run:
mock_run.return_value.returncode = 0
mock_run.return_value.stdout = f"Mocked: {' '.join(command)}"
result = subprocess.run(command, capture_output…How to generate and parse an interactive rebase TODO list in Python
Generate a Git interactive rebase TODO list from commit data and parse it back into structured records.
import re
from collections import namedtuple
Commit = namedtuple("Commit", ["hash", "subject"])
def generate_rebase_todo(commits, action="pick"):
todo_lines = []
for i, commit in enumerate(commits):
if i == 0 and action == "reword":
todo_lines.append(f"reword {commit.hash} {commit.subject…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):
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