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Copy-ready Python snippets by topic and difficulty — short, focused, and runnable in the browser editor.
How to Test X-Content-Type-Options nosniff in Python with Mocks
Mock httpx responses and verify that a server's X-Content-Type-Options header includes nosniff to prevent MIME sniffing.
import httpx
from unittest.mock import Mock, patch
def fetch_headers(url: str) -> dict:
response = httpx.get(url)
return dict(response.headers)
def mock_nosniff_check(response) -> bool:
content_type = response.headers.get("content-type", "")
x_content_type_options = response.headers.get("x-content-ty…How to Verify Passwords in Constant Time in Python
Use hmac.compare_digest to verify passwords in constant time, preventing timing attacks that could reveal password length or character positions.
import hmac
import time
# Mock of a constant-time password comparison (prevents timing attacks)
def verify_password(stored_password: str, supplied_password: str) -> bool:
# hmac.compare_digest runs in constant time (for a given length)
return hmac.compare_digest(stored_password.encode(), supplied_password.enc…How to implement OCSP stapling mock in Python
Simulate OCSP stapling with a caching mechanism that mocks certificate status lookups for TLS handshake validation.
import hashlib
import time
class OCSPStapler:
def __init__(self, cert_serial: str, issuer_hash: str):
self.cert_serial = cert_serial
self.issuer_hash = issuer_hash
self.cache = {}
def _mock_query_ocsp(self, serial: str) -> dict:
"""Simulate OCSP responder lookup."""
di…How to mock Argon2 password hashing in Python
This code demonstrates a mock Argon2 password hasher using HMAC-SHA256 iterations, providing hash and verify methods that mimic Argon2's salted, iterated derivation.
import hashlib
import hmac
import os
class Argon2Mock:
def __init__(self, salt_size=16, hash_len=32):
self.salt_size = salt_size
self.hash_len = hash_len
def hash(self, password: str, salt: bytes = None) -> str:
if salt is None:
salt = os.urandom(self.salt_size)
…How to mock DNS CAA record lookups in Python
Parse and filter DNS CAA records with a mock lookup function, demonstrating how certificate authorities validate domain authorization.
import dnslib
def parse_caa_record(record_string):
"""Parse a DNS CAA record string into its components."""
parts = record_string.split()
flags = int(parts[0])
tag = parts[1]
value = parts[2]
return flags, tag, value
def mock_caa_lookup(domain, caa_records):
"""Mock DNS CAA lookup that re…How to mock short TTL access tokens in Python
Simulate short-lived access tokens with a TTL, issue and validate them, and watch expiry behavior.
import time
import uuid
from datetime import datetime, timedelta
class AccessTokenManager:
def __init__(self, ttl_seconds=30):
self.ttl_seconds = ttl_seconds
self.tokens = {}
def issue_token(self):
token_id = uuid.uuid4().hex
expiry = datetime.now() + timedelta(seconds=self.t…How to redact secrets from log messages in Python
This code defines a logging.Filter subclass that automatically redacts sensitive keys like password, token, and API key from any dict logged.
import logging
from dataclasses import dataclass
@dataclass
class ApiResponse:
status: int
body: dict
class SecretRedactor(logging.Filter):
SENSITIVE_KEYS = {"password", "token", "secret", "api_key"}
def filter(self, record: logging.LogRecord) -> bool:
if isinstance(record.msg, dict):
…Implement RSA OAEP Padding in Python
Implements OAEP-style padding with MGF1 using SHA-256 from the Python standard library for RSA encryption prep.
import os
import hashlib
def mgf1(seed, length, hash_func=hashlib.sha256):
"""MGF1 mask generation function."""
output = b""
counter = 0
while len(output) < length:
c = counter.to_bytes(4, "big")
output += hash_func(seed + c).digest()
counter += 1
return output[:length]
…OAuth2 authorization code flow mock in Python
A minimal HTTP server that mocks the OAuth2 authorization code flow, issuing codes via /authorize and exchanging them for tokens at /token.
import json
from http.server import BaseHTTPRequestHandler, HTTPServer
from urllib.parse import urlparse, parse_qs
AUTH_CODE_STORE = {}
CLIENT_ID = "demo-client"
REDIRECT_URI = "http://localhost:8000/callback"
class OAuthHandler(BaseHTTPRequestHandler):
def do_GET(self):
parsed = urlparse(self.path)
…Auto Rollback on Error Rate Exceeded in Python
Simulate a service that monitors a rolling window of request errors and automatically rolls back when the error rate exceeds a threshold.
import random
import time
def simulate_requests(total_requests=1000, rollback_threshold=0.2):
"""
Simulate a service that automatically rolls back when the error rate
exceeds a threshold within a rolling window.
"""
window_size = 100
errors_seen = []
rolled_back = False
for req_num i…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):
…Design a Data Helper for Beginners in Python
Build a beginner-friendly DataHelper class that loads, saves, appends, and summarizes JSON data with atomic file writes.
import json
from datetime import datetime
from pathlib import Path
class DataHelper:
"""A beginner-friendly helper for common data operations."""
def __init__(self, data=None, filepath=None):
self.data = data if data is not None else []
self.filepath = Path(filepath) if filepath else None
…Generate a Mock Artifact Version Tag in Python
Creates a mock build artifact version tag from a branch name and build number, with a date stamp.
import re
from datetime import datetime
def mock_version_tag(branch_name: str, build_number: int) -> str:
"""Generate a mock build artifact version tag from branch and build number."""
branch_slug = re.sub(r'[^a-zA-Z0-9]+', '-', branch_name).strip('-').lower()
date_part = datetime.utcnow().strftime('%Y%m%…Generate a docker-compose.yml with mock services in Python
Build a docker-compose.yml string from a Python dict of service names and images, then write it to a file.
import yaml
from pathlib import Path
def generate_mock_compose(services: dict) -> str:
compose = {
"version": "3.9",
"services": {}
}
for name, image in services.items():
compose["services"][name] = {
"image": image,
"container_name": f"mock-{name}",
…How to Attach an SBOM to a Release in Python (Mock)
A mock function that attaches a Software Bill of Materials (SBOM) to a GitHub-style release by counting its components and marking the upload as attached.
import json
from pathlib import Path
def attach_sbom_mock(sbom_path: Path, release_tag: str, artifact_name: str) -> dict:
"""Mock attaching an SBOM to a release, returning the simulated upload result."""
sbom = json.loads(sbom_path.read_text())
return {
"release_tag": release_tag,
"artifa…How to Build a Data Helper for Production Deployment in Python
Build a reusable DataHelper class that loads configs, validates required keys, normalizes string values, and logs schema details — a production-ready data processing pattern.
import json
from pathlib import Path
from typing import Any, Dict
class DataHelper:
"""Common data processing patterns for production deployment."""
def __init__(self, config_path: str | Path):
self.config_path = Path(config_path)
self.config = self._load_config()
def _load_confi…How to Build a Simple Data Helper Class in Python
A beginner-friendly DataHelper class that safely saves and loads JSON files with automatic directory creation, perfect for production-style file handling.
from pathlib import Path
import json
class DataHelper:
"""Simple production-style helper for loading and saving JSON data."""
def __init__(self, data_dir="data"):
self.data_dir = Path(data_dir)
self.data_dir.mkdir(exist_ok=True)
def save(self, filename, data):
filepath = self.da…How to Build a Simple Data Helper Class in Python
A beginner-friendly DataHelper class that stores Python dataclass objects as JSON records to disk, with load, add, and save methods.
import json
from dataclasses import dataclass, asdict
from pathlib import Path
@dataclass
class User:
name: str
age: int
email: str
class DataHelper:
def __init__(self, filepath: str = "data.json"):
self.filepath = Path(filepath)
self._data = self._load()
def _load(self) -> l…How to Build a Synthetic Monitor Mock in Python
Simulates a synthetic monitoring system in Python that collects latency samples, averages them, and reports service status as UP or DEGRADED.
import random
import time
from dataclasses import dataclass, field
from statistics import mean
@dataclass
class SyntheticMonitor:
service: str
endpoint: str
latency_ms: list[float] = field(default_factory=list)
def check(self) -> float:
latency = random.uniform(50.0, 250.0)
self.late…How to Deploy Staging Then Production in Python
Walk through a staged deployment mock that promotes from staging to production in sequence with Python.
import time
def deploy_environment(name: str) -> None:
print(f"Deploying to {name}...")
time.sleep(0.1)
print(f"Deployed to {name} ✔")
def deploy_staging_then_prod() -> None:
environments = ["staging", "production"]
for env in environments:
deploy_environment(env)
if env == "stagi…How to Drain a Connection Pool Before Exit in Python
Gracefully close all pooled sockets using a thread-safe ConnectionPool that drains connections before program exit.
import socket
import threading
import time
import random
class ConnectionPool:
def __init__(self, size=5):
self.pool = []
self.lock = threading.Lock()
self.closed = False
for _ in range(size):
self.pool.append(self.create_connection())
def create_connection(sel…How to Expand a Contract and Migrate Data in Python
Expand an old data contract by renaming fields and adding defaults, then migrate to a final version with deepcopy isolation.
import json
from copy import deepcopy
# Mock data representing a user record (old contract)
old_contract = {
"id": 1,
"name": "Alice",
"email": "alice@example.com",
"age": 30,
"status": "active"
}
# Expanded contract: adds fields with defaults and renames some fields
expand_rules = {
"id": "u…How to Generate a Kubernetes Deployment Manifest in Python
Generate a Kubernetes Deployment manifest as YAML from a Python dictionary using PyYAML.
import yaml
deployment = {
"apiVersion": "apps/v1",
"kind": "Deployment",
"metadata": {
"name": "mock-app",
"labels": {"app": "mock-app"}
},
"spec": {
"replicas": 3,
"selector": {
"matchLabels": {"app": "mock-app"}
},
"template": {
…How to Implement a Data Helper Class in Python for Production Deployments
Build an environment-aware data helper in Python that loads config, extracts, transforms, and reports on JSON data using small, testable functions.
"""Production-style data helper for beginners.
Demonstrates:
- environment-aware config
- central data extraction
- small, testable functions
"""
import os
import json
from pathlib import Path
from typing import List, Dict, Any
def load_config(env: str = os.getenv("APP_ENV", "development")) -> Dict[str, Any]:
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