Using validate_assignment to enforce type coercion

validate_assignment_enforces_coercion.py

import pytest
from pydantic import BaseModel, ValidationError


class StrictPizza(BaseModel):
    toppings_count: int
    size: str

    class Config:
        validate_assignment = True  # enforces coercion


def test_pydantic_allows_setters_conversions():
    pizza = StrictPizza(toppings_count='4', size='XL')
    assert pizza.toppings_count == 4
    pizza.toppings_count = '5'
    assert pizza.toppings_count == 5
    with pytest.raises(ValidationError):
        pizza.toppings_count = 'no coercion'