Comparing parsing to validation

parse_vs_validation.py

from dataclasses import dataclass
from typing import List

import pytest

# User's name != '' and age > 0 and hobbies > []
# and a none empty list of hobbies
# example: {'name': 'John', 'age': 30, hobbies: ['Rock Climbing', 'Books']}


def validate_user(user: dict) -> None:  # 1
    name = user.get("name")
    if not name:
        raise ValueError("Users must have a non empty name")
    age = user.get("age", 0)
    if not age or age <= 0:
        raise ValueError("Users must have a positive age")
    hobbies = user.get("hobbies", [])
    if not hobbies:
        raise ValueError("Users must have at least one hobbie")


@pytest.mark.parametrize(
    "name,age,hobbies",
    [
        (None, 30, ["Rock Climbing"]),
        ("", 30, ["Rock Climbing"]),
        ("John", None, ["Rock Climbing"]),
        ("John", 0, ["Rock Climbing"]),
        ("John", 30, None),
        ("John", 30, []),
    ],
)
def test_users_with_invalid_fields_are_invalid(name, age, hobbies):
    with pytest.raises(ValueError):
        validate_user({"name": name, "age": age, "hobbies": hobbies})  # 2


def test_users_with_valid_fields_are_validated_properly():
    user_input = {"name": "John", "age": 40, "hobbies": ["Rock Climbing"]}
    validate_user(user_input)  # 3
    # 7


@dataclass
class User:
    name: str
    age: int
    hobbies: List[str]


def parse_user(user: dict) -> User:  # 4
    name = user.get("name")
    if not name:
        raise ValueError("Users must have a non empty name")
    age = user.get("age", 0)
    if not age or age <= 0:
        raise ValueError("Users must have a positive age")
    hobbies = user.get("hobbies", [])
    if not hobbies:
        raise ValueError("Users must have at least one hobbie")

    return User(name=name, age=age, hobbies=hobbies)


@pytest.mark.parametrize(
    "name,age,hobbies",
    [
        (None, 30, ["Rock Climbing"]),
        ("", 30, ["Rock Climbing"]),
        ("John", None, ["Rock Climbing"]),
        ("John", 0, ["Rock Climbing"]),
        ("John", 30, None),
        ("John", 30, []),
    ],
)
def test_users_with_invalid_fields_are_invalid(name, age, hobbies):
    with pytest.raises(ValueError):
        user_input = {"name": name, "age": age, "hobbies": hobbies}
        parse_user(user_input)  # 5


def test_users_with_valid_fields_are_validated_properly():
    user = parse_user({"name": "John", "age": 40, "hobbies": ["Rock Climbing"]})
    # 7

    assert user == User(name="John", age=40, hobbies=["Rock Climbing"])  # 6