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How to Cross Post Markdown to dev.to API in Python
A Python function that POSTs markdown content to the dev.to API and handles HTTP or URLError exceptions with mock API testing.
import json
from urllib import request, error
def cross_post_to_devto(markdown_content, api_key, devto_api_url="https://dev.to/api/articles"):
"""
Mock cross-posting of markdown content to the dev.to API.
Returns the API response or an error message.
"""
payload = json.dumps({
"article": …How to Mock an Ansible Inventory in Python
Load an Ansible-style inventory JSON file into Python and simulate a playbook run across hosts and groups.
import json
from pathlib import Path
class InventoryMock:
def __init__(self, inventory_file: str):
self.inventory_file = Path(inventory_file)
self.hosts = {}
def load(self):
if not self.inventory_file.exists():
raise FileNotFoundError(f"Inventory file {self.inventory_file…How to Mock subprocess Calls in Python with unittest.mock
A Python script that wraps Vagrant up/destroy commands using subprocess, with tests that mock the subprocess call to simulate outputs and errors.
import subprocess
from unittest.mock import patch, Mock
def run_vagrant(action: str) -> str:
result = subprocess.run(
["vagrant", action],
capture_output=True,
text=True,
check=False,
)
return result.stdout.strip()
def vagrant_wrapper(action: str) -> str:
if action n…How to Parse Terraform Plan Output in Python
Parse mock Terraform plan output text into structured add, change, and destroy lists using Python.
import json
from typing import Dict, List
def parse_terraform_plan_output(plan_output_text: str) -> Dict[str, List[str]]:
"""
Parses a mock Terraform plan output text into a structured dictionary.
"""
parsed: Dict[str, List[str]] = {"add": [], "change": [], "destroy": []}
for line in plan_output_…How to Update a Hosts File to Block Distractions in Python
This script updates a local hosts file (or a demo file) by adding or updating entries to block distracting websites like Facebook and Twitter.
from pathlib import Path
def update_hosts(entries):
"""
Add or update blocking entries in the hosts file.
Uses a local demo file by default to avoid system changes.
"""
hosts_path = Path("demo_hosts.txt")
# Create demo file if it doesn't exist
if not hosts_path.exists():
hosts…How to Write an IP Block List to hosts.deny in Python
This Python script validates a list of IP addresses and CIDR ranges, then writes them to a hosts.deny file to block connections at the TCP wrapper level.
from ipaddress import ip_network
def write_hosts_deny(ip_list, output_file="hosts.deny"):
with open(output_file, "w") as f:
for ip in ip_list:
try:
ip_network(ip)
f.write(f"ALL: {ip}\n")
except ValueError:
continue
print(f"Written…How to generate website performance reports from HTTP requests in Python
Measure and report website load time, status code, and content size using Python's standard library.
import urllib.request
import time
def measure_website_load_time(url):
"""Measures total loading time of a website."""
start_time = time.time()
try:
with urllib.request.urlopen(url, timeout=10) as response:
content = response.read()
status_code = response.status
…Monitor Website Uptime with Python
Periodically check if a website is reachable and its HTTP status is 200, logging the status with timestamps.
import requests
import time
def check_website(url):
try:
response = requests.get(url, timeout=5)
if response.status_code == 200:
return True
else:
return False
except requests.ConnectionError:
return False
except requests.Timeout:
return Fals…How to List Failed Records in a Dead Letter Queue Mock in Python
A mock Dead Letter Queue stores failed processing records with error details and timestamps, lists them, and exports to JSON.
import json
from datetime import datetime, timedelta
import random
class DeadLetterQueue:
def __init__(self):
self.failed_records = []
def add_failed_record(self, record_id, payload, error_message):
self.failed_records.append({
"record_id": record_id,
"payload": paylo…How to Merge Multiple Data Sources in Python
A beginner-friendly helper that merges lists of dictionaries from multiple sources into one combined list using key filtering.
import json
def merge_pipeline_data(*data_sources, keys=()):
"""Merge multiple data sources (list of dicts) into a single list of merged dicts.
Args:
*data_sources: One or more lists of dictionaries.
keys: Tuple of keys to include from each source (empty means all keys).
Returns:
…How to Auto-Suggest a SemVer Bump From Git Commit Messages in Python
This code scans Git commit messages (recent or sample) and suggests the next Semantic Versioning bump type — major, minor, patch, or none.
import re
import subprocess
from pathlib import Path
def get_commit_messages(path="."):
"""Read commit messages from a repo or use sample messages."""
if (Path(path) / ".git").exists():
out = subprocess.run(
["git", "-C", path, "log", "--pretty=%s"], capture_output=True, text=True
…How to Create a Git Branch if it Doesn't Exist in Python
Utility script that checks if a Git branch exists locally and either creates it or checks it out, with error handling.
import subprocess
import sys
def ensure_branch(branch_name):
"""Create a Git branch if it doesn't exist, otherwise checkout it."""
try:
# Check if the branch exists locally
result = subprocess.run(
["git", "branch", "--list", branch_name],
capture_output=True,
…How to Mock subprocess.run in Python Tests
Mock subprocess.run to test a Git submodule update command without executing it in your test suite.
import subprocess
from unittest.mock import Mock, patch
def update_submodules():
subprocess.run(["git", "submodule", "update", "--init", "--recursive"], check=True)
with patch("subprocess.run") as mock_run:
mock_run.return_value = Mock(returncode=0)
update_submodules()
mock_run.assert_called_once_wit…Generate an Idempotency-Key header mock with UUID in Python
This code provides a mock idempotency service that generates a UUID-based Idempotency-Key header token and validates it, useful for simulating production API behavior in tests.
import uuid
class MockIdempotencyService:
def __init__(self):
self._tokens = {}
def get_token(self, header_name="Idempotency-Key"):
token = str(uuid.uuid4())
self._tokens[header_name] = token
return token
def validate(self, header_name="Idempotency-Key"):
return s…How to Create a Mock STS AssumeRole Credentials Dict in Python
Build a realistic AWS STS AssumeRole response dict with temporary credentials, expiry time, and assumed role ARN for local testing.
import json
from datetime import datetime, timedelta, timezone
def mock_sts_credentials(role_arn, session_name, duration=3600):
now = datetime.now(timezone.utc)
expiration = now + timedelta(seconds=duration)
credentials = {
"Credentials": {
"AccessKeyId": "ASIAEXAMPLEACCESSKEY",
…How to Implement Retry with Exponential Backoff for Cloud API 429 Errors in Python
Implement a retry-with-backoff loop in Python to handle 429 throttling errors from cloud APIs, using exponential delay between attempts.
import time
import random
import requests
def api_call(attempt):
"""Mock cloud API that returns 429 for the first two attempts."""
if attempt < 2:
return 429, "Too Many Requests"
return 200, {"data": "success"}
def retry_with_backoff(api_func, max_retries=3, base_delay=0.1):
for attempt in …How to Mock Click CLI App Subcommands in Python
Simulate Click-style CLI subcommand calls in Python by using argparse with subparsers and mocking sys.argv in tests or scripts.
import sys
import argparse
def do_greet(args):
print(f"Hello, {args.name}!")
def do_goodbye(args):
print(f"Goodbye, {args.name}!")
def main():
parser = argparse.ArgumentParser(prog="clickapp")
subparsers = parser.add_subparsers(dest="command", required=True)
greet_parser = subparsers.add_par…How to Mock Commitizen Version Bump in Python
Simulate commitizen's version bump logic and mock the subprocess call to avoid real execution in tests.
import subprocess
from unittest.mock import patch, MagicMock
def bump_version(current_version: str, increment: str = "patch") -> str:
"""Simulate commitizen's version bump logic."""
major, minor, patch = map(int, current_version.split("."))
if increment == "major":
major += 1
minor = 0
…How to Mock Poetry pyproject.toml Dependencies Sections in Python
Parse and extract dependency lists from Poetry-style pyproject.toml text using Python's standard library.
from pathlib import Path
import re
def parse_pyproject_dependencies(text):
"""Extract dependencies from a pyproject.toml style text."""
lines = text.splitlines()
sections = {
"dependencies": [],
"dev": [],
"optional": [],
}
current_section = None
patterns = {
…How to Parametrize Tests in Python with pytest
This code demonstrates how to use pytest's @pytest.mark.parametrize decorator to run a single test function against multiple input sets, ensuring comprehensive coverage with minimal code duplication.
import pytest
def multiply(a, b):
return a * b
@pytest.mark.parametrize("x, y, expected", [
(2, 3, 6),
(4, 5, 20),
(0, 10, 0),
(7, 1, 7),
])
def test_multiply(x, y, expected):
result = multiply(x, y)
assert result == expected, f"multiply({x}, {y}) = {result}, expected {expected}"
if _…How to Use pytest Fixtures and conftest.py for Shared Setup in Python
Learn how to define reusable pytest fixtures for shared setup and use them to keep tests clean and maintainable.
import pytest
class Calculator:
def add(self, a, b):
return a + b
def multiply(self, a, b):
return a * b
@pytest.fixture
def calc():
return Calculator()
@pytest.fixture
def sample_numbers():
return (3, 5)
def test_add(calc, sample_numbers):
a, b = sample_numbers
assert c…pytest mark slow skip integration
Uses pytest markers to select fast tests, skip unfinished ones, and run integration checks with verbose output.
import pytest
def test_fast():
assert 1 + 1 == 2
@pytest.mark.slow
def test_slow():
import time
time.sleep(1)
assert 5 * 5 == 25
@pytest.mark.skip(reason="Not ready for production")
def test_skipped():
assert 2 + 2 == 5
@pytest.mark.integration
def test_integration():
database = {"users": […How to Test HTTPX Async Client Pool Reuse with Mocks in Python
Mock an httpx.AsyncClient to verify connection pool reuse by asserting GET calls share a single client instance across concurrent async requests.
import asyncio
import httpx
from unittest.mock import AsyncMock, patch, Mock
async def fetch_with_pool(client, url, n_reuses=3):
results = []
for i in range(n_reuses):
resp = await client.get(url)
results.append(resp.status_code)
await asyncio.sleep(0) # yield to loop to mimic real us…How to Use Array Typecodes for Compact Numeric Storage in Python
This code demonstrates how to use the `array` module with typecodes to store integers, floats, and bytes in a memory-efficient way compared to standard Python lists.
from array import array
def demonstrate_array_types():
# Compact integer arrays
small_ints = array('i', [1, 2, 3, 4, 5])
unsigned_ints = array('I', [10, 20, 30])
# Floating point arrays
floats = array('f', [1.5, 2.5, 3.5])
doubles = array('d', [1.123456789, 2.987654321])
# Charac…Browse by section
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