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Testing & modern typing

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

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Dataclass with Type Hints Fields in Python

Create a data class with typed fields and default values, then instantiate and inspect it.

from dataclasses import dataclass


@dataclass
class Person:
    name: str
    age: int
    email: str = "unknown@example.com"
    is_active: bool = True


if __name__ == "__main__":
    person = Person(name="Alice", age=30)
    print(person)
    print(f"Name: {person.name}, Age: {person.age}, Email: {person.email}, A…

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Testing & modern typing easy

How to Use TypedDict and Dataclasses in Python

Create typed data structures with TypedDict and dataclasses, then use them as helper functions for describing objects in a type-safe way.

typing typdict dataclass

Python

from typing import TypedDict, NotRequired, Optional
from dataclasses import dataclass


class User(TypedDict):
    name: str
    age: NotRequired[int]
    email: Optional[str]


@dataclass
class Product:
    id: int
    title: str
    price: float = 0.0


def describe_user(user: User) -> str:
    age = user.get("age",…

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Testing & modern typing easy

How to Validate Dataclass Fields with Python Type Hints

A beginner-friendly helper that checks if instance attributes match their declared type hints using dataclasses and get_type_hints.

dataclasses type-hints validation

Python

from typing import Any, TypeVar, get_type_hints
from dataclasses import dataclass

T = TypeVar("T")

@dataclass
class User:
    name: str
    age: int
    email: str

def validate_fields(obj: Any) -> dict[str, bool]:
    """Check if object attributes match declared type hints."""
    hints = get_type_hints(obj.__class…

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