test_converter.py

rates_api = {
    "USDBRL": 3.37
}


def get_rate(f, t):
    return rates_api[f+t]


class Converter():
    def __init__(self, rates):
        self.rates = rates

    def convert(self, from_currency, from_amount, to_currency):
        if from_currency == to_currency:
            return from_amount

        return get_rate(from_currency, to_currency) * from_amount


import pytest


@pytest.fixture
def ratesdb():
    return rates_api


@pytest.fixture
def convert(ratesdb):
    return Converter(ratesdb).convert


def test_one_brl_should_return_one_brl(convert):
    assert convert(from_currency="BRL", from_amount=0, to_currency="BRL") == 0
    assert convert(from_currency="BRL", from_amount=1, to_currency="BRL") == 1
    assert convert(from_currency="BRL", from_amount=2, to_currency="BRL") == 2


def test_convert_one_usd_should_return_312_brl(convert, mocker):
    mocker.patch("test_converter.get_rate", return_value=3.12)

    assert convert(from_currency="USD", from_amount=1, to_currency="BRL") == 3.12


def test_broken_assert():
    assert True


def test_coffeebreak():
    assert True