Mastering Object-Oriented Python - Second Edition

Assertion checking

To confirm the exception raised by a test, the unittest.TestCase class has methods like assertRaises(). When working with pytest, we have a distinct approach to testing this feature. The pytest package offers a context manager named raises to help detect the exception that is raised. The raises context is shown in this example:

from pytest import raisesdef test_card_factory():    c1 = card(1, Suit.CLUB)    assert isinstance(c1, AceCard)    c2 = card(2, Suit.DIAMOND)    assert isinstance(c1, Card)    c10 = card(10, Suit.HEART)    assert isinstance(c10, Card)    cj = card(11, Suit.SPADE)    assert isinstance(cj, FaceCard)    ck = card(13, Suit.CLUB)    assert isinstance(ck, FaceCard)    with raises(LogicError):        c14 = card(14, Suit.DIAMOND)    with raises(LogicError): ...