[lang-ref] ( null_coalescing ) ( python )

def test_null_coalescing():
    #
    # Want: x = a ?? -1  (C#/Swift)
    #    or x = a ?: -1` (so-called Elvis operator in Kotlin/Groovy)
    # But there is no compact syntax in Python, so use a verbose one.
    pytest.skip('Not supported')

@pytest.mark.parametrize(
    'a, expected',
    [
        (None, -1),
        (3, 3),
        (0, 0),
    ],
)
def test_null_coalescing_alternative1(a, expected):
    # Want: x = a ?? -1  (C#/Swift)
    #    or x = a ?: -1` (so-called Elvis operator in Kotlin/Groovy)
    # But there is no compact syntax in Python, so use a verbose one.

    if a is None:
        x = -1
    else:
        x = a

    assert x == expected

@pytest.mark.parametrize(
    'a, expected',
    [
        (None, -1),
        (3, 3),
        (0, 0),
    ],
)
def test_null_coalescing_alternative2(a, expected):
    # Same logic in a single expression (less readable for me).
    x = -1 if a is None else a
    assert x == expected

@pytest.mark.parametrize(
    'a, expected',
    [
        (None, -1),
        (3, 3),
        (0, -1), # this is not what I want
    ],
)
def test_null_coalescing_alternative3(a, expected):
    # deprecated for me: `or` uses truthiness, not a None check.
    x = a or -1
    assert x == expected