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How to Evaluate Mock NACL Rules in Python
Simulate numbered AWS Network ACL rule evaluation with HMAC integrity checks on request payloads.
import base64
import json
import hmac
import hashlib
def evaluate_mock_rule(rule_number, request_data, secret):
"""
Simulates evaluating an NACL-like numbered rule by:
1. Checking if the rule number exists in the mock policy.
2. Computing an HMAC over the request payload for integrity.
"""
# M…How to Parse Cloud JSON Data in Python
A helper function that safely parses JSON payloads from cloud services into a clean dict with defaults and error handling.
import json
from typing import Dict, Any
def parse_cloud_data(payload: str) -> Dict[str, Any]:
"""Parse a JSON payload from a cloud service into a clean dict."""
try:
data = json.loads(payload)
return {
"status": data.get("status", "unknown"),
"region": data.get("region…How to Parse Terraform Output JSON in Python
Parse Terraform's JSON output into a flat dictionary of values using the standard library json module.
import json
def parse_terraform_output(raw_output):
"""Parse Terraform JSON output into a flat dict of values."""
try:
data = json.loads(raw_output)
except json.JSONDecodeError as e:
raise ValueError(f"Invalid JSON: {e}")
return {key: value["value"] for key, value in data.items()}
i…How to Parse an AWS API Gateway Proxy Event in Python
Extract and parse common fields from a mock API Gateway proxy event, turning the JSON body into a native Python dict.
import json
from typing import Any, Dict, Optional
def parse_proxy_event(event: Dict[str, Any]) -> Dict[str, Any]:
"""Extract and parse common fields from an API Gateway proxy event."""
body = event.get("body", "")
if isinstance(body, str):
body = json.loads(body) if body else {}
elif body is…Mock AWS Spot Instance Interruption Handler in Python
A Python class that simulates AWS Spot instance interruption checks, handling the 10% chance of termination, logging state-saving, and storing notice details.
import time
import random
class SpotInstanceHandler:
def __init__(self, instance_id):
self.instance_id = instance_id
self.interruption_notices = []
def start(self):
print(f"Spot instance {self.instance_id} started")
def check_interruption(self):
# Simulate random interrup…Mock Lambda handler event context dict in Python
Simulates an AWS Lambda invocation by passing a mock event dict and context object to a handler, then prints the response.
import json
def lambda_handler(event, context):
"""
A mock AWS Lambda handler that processes an event dict and context object.
Demonstrates the typical Lambda function signature and basic event/context usage.
"""
print("Received event:", json.dumps(event, indent=2))
print("Function name:", co…Mock SNS publish subscribe fanout in Python
Simulates AWS SNS publish/subscribe with an in-memory topic-to-endpoints dict that fans out messages to all subscribers.
class SNSMock:
def __init__(self):
self.topics = {}
def create_topic(self, name):
if name not in self.topics:
self.topics[name] = []
return f"arn:aws:sns:us-east-1:123456789012:{name}"
def subscribe(self, topic_name, endpoint):
self.topics.setdefault(topic_name…Pick a Random Region with Mock Carbon Intensity in Python
Selects a random region from a list and generates a mock carbon intensity value using Python's random module.
import random
def pick_region_intensity(regions, seed=42):
random.seed(seed)
selected = random.choice(regions)
intensity = random.randint(1, 10)
return selected, intensity
if __name__ == "__main__":
regions = ["North", "South", "East", "West"]
selected, intensity = pick_region_intensity(regio…Build a Recipe Runner Mock in Python
A Python script that mocks a command runner recipe system: maps recipe names to shell commands, executes them with subprocess, and prints the output and exit code.
import subprocess
import sys
def run_recipe(recipe: str) -> None:
"""Simulate a command runner recipe by printing the command and exit code."""
print(f"Running recipe: {recipe}")
result = subprocess.run(recipe, shell=True, capture_output=True, text=True)
print(f"Exit code: {result.returncode}")
i…Build a Textual TUI App Skeleton in Python
Create a minimal Textual terminal UI app with a header, label, button, and footer, ready for interactive mock demonstrations.
from textual.app import App, ComposeResult
from textual.widgets import Header, Footer, Button, Label
class MockApp(App):
"""A minimal Textual TUI app skeleton."""
BINDINGS = [("q", "quit", "Quit")]
def compose(self) -> ComposeResult:
"""Create child widgets."""
yield Header()
yie…Configure ruff linter rules in pyproject.toml with Python
Reads an existing pyproject.toml and merges common ruff linter rules into the tool.ruff section using Python's tomllib.
import tomllib
from pathlib import Path
def configure_ruff_linter_rules(project_path: str = ".") -> dict:
"""Add common ruff linter rules to pyproject.toml if missing."""
pyproject_path = Path(project_path) / "pyproject.toml"
# Default config for ruff linter with practical rules
ruff_config = {
…How to Build a Chainable Filter Helper in Python
A beginner-friendly dataclass helper that chains filters, uniqueness, and slicing on any sequence, returning a plain list at the end.
from dataclasses import dataclass
from typing import Callable, Iterator, Sequence, TypeVar
T = TypeVar("T")
@dataclass
class FilterAssistant:
"""Beginner-friendly helper to filter any collection."""
data: Sequence[T]
def where(self, predicate: Callable[[T], bool]) -> "FilterAssistant":
return …How to Create Interactive CLI Prompts in Python with questionary
Build mock interactive command-line prompts using questionary's select and text widgets with graceful handling of user cancellation.
import questionary
def main():
# Mock interactive prompts using questionary's select and text
choice = questionary.select(
"What is your favorite programming language?",
choices=["Python", "JavaScript", "Go", "Rust"]
).ask()
# ask() returns None if user cancels; handle gracefully
…How to Create a Rich Console Progress Bar Mock in Python
This code uses Rich's Console and Progress API to build a simulated progress bar for a long-running task, updating progress and printing status messages.
import time
from rich.console import Console
from rich.progress import Progress, BarColumn, TextColumn, PercentageColumn
console = Console()
def run_simulation():
console.print("[bold cyan]Starting simulated task...[/bold cyan]")
with Progress(
TextColumn("[bold blue]{task.description}[/bold blu…How to Define Nox Sessions in Python
Automate repetitive tasks like testing and linting with reusable Nox sessions.
import nox
@nox.session(python=["3.9", "3.10"])
def tests(session):
session.install("pytest")
session.run("pytest")
@nox.session(python="3.9")
def lint(session):
session.install("ruff")
session.run("ruff", "check", ".")
if __name__ == "__main__":
print("Nox sessions defined: tests, lint")
…How to List Pre-commit Hooks from YAML Config in Python
Parse a .pre-commit-config.yaml file with PyYAML and print every hook ID paired with its source repository.
import yaml
pre_commit_config = """
repos:
- repo: https://github.com/pre-commit/pre-commit-hooks
rev: v4.5.0
hooks:
- id: trailing-whitespace
- id: end-of-file-fixer
- id: check-yaml
- repo: https://github.com/psf/black
rev: 23.11.0
hooks:
- id: black
"""
def list_hooks(c…How to Load and Inspect CSV Data with a Dataclass Helper in Python
This code defines a DataHelper dataclass that reads a CSV file into a list of dictionaries and prints basic dataset information.
from pathlib import Path
from dataclasses import dataclass
from typing import Any
@dataclass
class DataHelper:
"""Simple helper for loading and inspecting CSV data."""
filepath: Path
def load_csv(self, *, delimiter: str = ",") -> list[dict[str, Any]]:
"""Read CSV into a list of dictionaries."""
…How to Mock Twine Upload to TestPyPI in Python
Simulate a twine upload to TestPyPI with a dry-run mock function that validates distribution files and prints the intended upload action without any network call.
import subprocess
import sys
# Mock twine upload to TestPyPI using subprocess dry-run
def mock_twine_upload(dist_file: str, repo_url: str = "https://test.pypi.org/legacy/") -> None:
"""Simulate twine upload by checking dist file and printing intended action."""
if not dist_file.endswith((".whl", ".tar.gz")):
…How to Mock a pipx Install Command in Python
Simulate a pipx install step by validating tool names and printing the exact command output a real pipx run would produce.
import subprocess
import sys
def install_with_pipx(tool_name: str) -> str:
"""
Mock a pipx install step by validating the tool name and
simulating the installation command output.
"""
allowed_tools = {"black", "flake8", "mypy", "ruff"}
if tool_name not in allowed_tools:
raise ValueErr…How to Mock isort Output to Test Import Sorting in Python
Uses isort with check mode and a unittest mock to verify whether a Python source string has correctly sorted imports.
import isort
from unittest.mock import patch
code = """
import os
import sys
import json
import pathlib
"""
def check_imports_sorted(code_str):
with patch("isort.api.output") as mock_output:
isort.code(code_str, check=True, show_diff=True)
return mock_output.called
if __name__ == "__main__":
…How to Read the Python Path from VS Code settings.json in Python
This code loads VS Code's settings.json file and extracts the python.defaultInterpreterPath value, with a mock demonstration for testing.
import json
from pathlib import Path
from unittest.mock import patch
def read_vscode_python_path(settings_path: Path) -> str:
"""Extract python.defaultInterpreterPath from VS Code settings.json."""
with open(settings_path, "r") as f:
settings = json.load(f)
return settings.get("python", {}).get("d…How to Save and Load JSON Files in Python
Create a simple data helper to save Python dictionaries as pretty-printed JSON files and load them back reliably using pathlib and the stdlib json module.
import json
from pathlib import Path
from typing import Any
def save_json(data: Any, filename: str) -> None:
"""Save data as pretty-printed JSON to the current directory."""
path = Path(filename)
with path.open("w", encoding="utf-8") as f:
json.dump(data, f, indent=2, ensure_ascii=False)
def lo…How to Use prompt_toolkit Autocomplete in Python
Demonstrates an interactive command-line prompt with autocomplete using prompt_toolkit's WordCompleter and a mock dataset.
from prompt_toolkit import prompt
from prompt_toolkit.completion import WordCompleter
def main():
"""Demo of prompt_toolkit autocomplete with a mock dataset."""
# A simple mock "database" of programming languages
languages = [
"Python", "Java", "JavaScript", "TypeScript", "C++", "C#",
"Go"…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…Browse by section
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