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Testing & modern typing

pytest basics, mocks, type hints, TypedDict, Protocol, and static-checking patterns.

5 matches

How to Load Test a Local API with Locust in Python

Defines a Locust load test that simulates traffic to local endpoints, enabling manual load testing against a development server.

locust load-testing performance-testing

Python

from locust import HttpUser, task, between


class WebsiteUser(HttpUser):
    wait_time = between(1, 3)

    @task
    def home_page(self):
        self.client.get("/")

    @task(3)
    def about_page(self):
        self.client.get("/about")


if __name__ == "__main__":
    print("Run with: locust -f this_file.py --h…

16 0 Open

Testing & modern typing medium

How to Run an Integration Test with Docker Compose Mock in Python

Run a Python integration test against a docker-compose environment, using mocks to simulate service health and business logic responses.

docker integration-testing mocking

Python

import subprocess
import json
from typing import Dict

def run_integration_test() -> Dict[str, str]:
    """
    Simulates an integration test against a docker-compose environment
    using a mock service that returns canned responses.
    """
    # Mock docker-compose environment check
    env_ready = subprocess.run(…

15 0 Open

Testing & modern typing medium

How to Use Stubs, Fakes, Spies, and Mocks in Python Testing

Implement four types of test doubles — stubs, fakes, spies, and mocks — as subclasses of a PaymentGateway interface to replace real dependencies during testing.

testing mocks stubs

Python

class PaymentGateway:
    def charge(self, amount):
        raise NotImplementedError


class StubPaymentGateway(PaymentGateway):
    """Returns a fixed response without any logic."""
    def charge(self, amount):
        return {"success": True, "transaction_id": "stub-12345"}


class FakePaymentGateway(PaymentGatewa…

12 0 Open

Testing & modern typing medium

How to Use TypedDict for Data Validation in Python

Define a TypedDict schema and validate raw dictionary input with type hints for safer, more readable data handling.

typeddict typing validation

Python

from typing import Any, Dict, List, Optional, Union, TypedDict, Literal

class Product(TypedDict):
    product_id: int
    name: str
    price: Union[int, float]
    in_stock: bool
    tags: Optional[List[str]]

def validate_product(data: Dict[str, Any]) -> Product:
    product_id: int = int(data["product_id"])
    na…

15 0 Open

Testing & modern typing medium

How to Validate Data in Python with Typing Hints

Build a runtime validation helper that checks values against Python type hints like Optional, list, and basic types.

typing validation type-hints

Python

from typing import Any, Optional, Union, TypeVar, get_origin, get_args

T = TypeVar("T")

def validate(value: Any, expected_type: type) -> Optional[str]:
    """Returns an error message if value doesn't match expected_type, else None."""
    # Handle Optional[...] types
    origin = get_origin(expected_type)
    if or…

14 0 Open

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