Jan Giacomelli jangia

Backend Lead @ REN | Expert in Python, TDD, AWS, FastAPI, skiing, and windsurfing.

jangia / test_subscription.py

Created November 27, 2025 15:41

Time Travel in Your Tests with freezegun

	from dataclasses import dataclass
	from datetime import datetime, timedelta

	from freezegun import freeze_time


	@dataclass
	class Subscription:
	plan: str
	started_at: datetime

jangia / test_custom_assertion_error_message.py

Created September 16, 2025 15:12

test_custom_assertion_error_message.py

	import requests
	from http import HTTPStatus


	def test_default_assertion_message():
	user = {"email": "<EMAIL>", "is_happy": False}
	assert user["is_happy"] is True
	# > assert user["is_happy"] is True
	# E assert False is True

jangia / test_named_parametrized_examples.py

Last active April 3, 2025 13:14

	import re

	import pytest

	REDIRECT_REGEX = r"(^/([A-Za-z0-9#&?=]+\|$)\|^https://my.domain\.com/[A-Za-z0-9#&?=/]*$)"


	def is_valid_success_url(url: str) -> bool:
	return bool(re.match(REDIRECT_REGEX, url))

jangia / test_spies.py

Created March 13, 2025 14:57

create_autospec – easily ensure that mocked objects are called correctly (Spies)

	from unittest.mock import MagicMock, create_autospec


	class MyCRMService:
	def sync_user(self, *, first_name: str, last_name: str, email: str) -> None:
	print("Calling MyCRM's REST API to send data there. That's slow and unreliable.")


	class CreateUser:
	def __init__(self, *, crm_service: MyCRMService) -> None:

jangia / test_stubs.py

Created March 13, 2025 14:55

create_autospec – easily ensure that mocked objects are called correctly (Stubs)

	import time
	from unittest.mock import MagicMock, create_autospec


	class SentimentClassifier:
	def predict(self, text: str) -> str:
	# Imagine that prediction is taking a long time
	time.sleep(5)
	return "positive"

jangia / test_email_validator_abuse.py

Created February 5, 2025 19:57

Parametrize tests using pytest - abuse

	import pytest

	from email_validator import is_valid_email


	@pytest.mark.parametrize(
	"email,is_valid",
	[
	("[email protected]", True),
	("gqehtjwyeumi,", False),

jangia / email_validator.py

Last active February 5, 2025 19:52

Parametrize tests using pytest

	import re


	def is_valid_email(email: str) -> bool:
	return bool(re.search(r"^[\w\.\-\+']+@[\w\.\-]+\.\w+$", email))

jangia / models.py

Created April 10, 2024 05:41

Test behavior, not implementation details - part 3

	from dataclasses import dataclass
	from enum import Enum


	class TaskStatus(str, Enum):
	OPEN = "OPEN"
	CLOSED = "CLOSED"


	@dataclass

jangia / tests.py

Created March 27, 2024 19:11

Testing behavior, not implementation details – part 2 (tests)

	import sqlite3

	import pytest

	from models import Task, TaskStatus
	from store import TaskStoreSQLite


	@pytest.fixture
	def connection(tmp_path) -> sqlite3.Connection:

jangia / models.py

Created March 27, 2024 18:48

Testing behavior, not implementation details – part 2 (model & store)

	from dataclasses import dataclass
	from enum import Enum


	class TaskStatus(str, Enum):
	OPEN = "OPEN"
	CLOSED = "CLOSED"


	@dataclass