def test_flatten() -> None:
m_empty: Maybe[Maybe[str]] = Just(Nothing())
m_flat: Maybe[str] = m_empty.flatten()
assert m_flat.or_else("backup") == "backup"
m_full: Maybe[Maybe[str]] = Just(Just("becon"))
assert m_full.flatten().or_else("backup") == "becon"
def test_as_iterable() -> None:
m_empty: Maybe[str] = Nothing()
i = 0
for n in m_empty:
i = i + 1
assert i == 0
for n in Just("one"):
i = i + 1
assert i == 1
assert len(m_empty) == 0
assert len(Just("one")) == 1
def test_from_nothing() -> None:
m: Maybe[int] = Nothing()
result: Result[int, str] = Result.fromMaybe(m, "error")
assert Err("error") == result
def test_from_empty_list() -> None:
assert Nothing() == Maybe.fromList([])
def test_last() -> None:
maybes: List[Maybe[int]] = [Just(1), Just(2), Nothing()]
assert Just(2) == last(maybes)
def test_first() -> None:
maybes: List[Maybe[int]] = [Nothing(), Just(1), Just(2)]
assert Just(1) == first(maybes)
def test_nothing_withdefault() -> None:
m: Maybe[int] = Nothing()
assert 0 == m.withDefault(0)
def test_apply_nothing_to_nothing() -> None:
m: Maybe[int] = Nothing()
f: Maybe[Callable[[int], int]] = Nothing()
assert Nothing() == m.apply(f)
def test_nothing_to_result() -> None:
assert Err("oops") == Nothing().toResult("oops")
def test_bind_nothing() -> None:
m: Maybe[int] = Nothing()
increment: Callable[[int], Maybe[int]] = lambda x: Just(x + 1)
assert Nothing() == m.bind(increment)
def test_or_else() -> None:
m_empty: Maybe[str] = Nothing()
assert m_empty.or_else("backup") == "backup"
m_full: Maybe[str] = Just("becon")
assert m_full.or_else("backup") == "becon"
def test_nothing_to_optional() -> None:
assert None == Nothing().toOptional()
def test_from_optional_none() -> None:
assert Nothing() == Maybe.fromOptional(None)
def test_err_to_maybe() -> None:
result: Result[int, str] = Err("error")
assert Nothing() == result.toMaybe()
def test_apply_just_to_nothing() -> None:
m: Maybe[int] = Nothing()
increment: Callable[[int], int] = lambda x: x + 1
assert Nothing() == m.apply(Maybe.pure(increment))
def __init__(self, f):
self.subscribers = []
self.cache = Nothing()
self.semaphore = threading.BoundedSemaphore(1)
f(self.__callback)
def test_from_err() -> None:
assert Nothing() == Maybe.fromResult(Err("oops"))